EP2307225A1 - Protection against load dump on multiple automobile interfaces - Google Patents

Protection against load dump on multiple automobile interfaces

Info

Publication number
EP2307225A1
EP2307225A1 EP08789407A EP08789407A EP2307225A1 EP 2307225 A1 EP2307225 A1 EP 2307225A1 EP 08789407 A EP08789407 A EP 08789407A EP 08789407 A EP08789407 A EP 08789407A EP 2307225 A1 EP2307225 A1 EP 2307225A1
Authority
EP
European Patent Office
Prior art keywords
interface
load dump
electrical
voltage
power supply
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08789407A
Other languages
German (de)
French (fr)
Other versions
EP2307225A4 (en
Inventor
Wei Ming Dan Chia
Ming Hua Lim
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Continental Automotive GmbH
Original Assignee
Continental Automotive GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Continental Automotive GmbH filed Critical Continental Automotive GmbH
Publication of EP2307225A1 publication Critical patent/EP2307225A1/en
Publication of EP2307225A4 publication Critical patent/EP2307225A4/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/04—Constant-current supply systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage

Definitions

  • This application relates to a protection against load dump.
  • this application relates to the load dump at automobile interfaces.
  • US 6 650 521 B2 discloses a protection circuit for a load dump condition that employs a voltage division circuit to reduce voltage applied to a system under test (SUT). This allows the applied voltage to be reduced to permit a use of a lower voltage rating for power MOSFETs (metal-oxide- semiconductor field-effect transistor) in the SUT.
  • the voltage division circuit employs a resistor and a switch. The switch is closed at voltages higher than a given value at terminals of the SUT and it is opened when the applied voltage reduces below the given value.
  • US 6 346 797 Bl discloses an alternator system having an AC (alternating current) machine that includes a switched-mode rectifier operating at a duty cycle that is based upon at least one of an EMF (electromagnetic field), a frequency, or a speed of operation of the AC machine.
  • the switched-mode rectifier operates such that the alternator system provides a load match that results in output power levels that are relatively high compared with output power levels of conventional alternator systems.
  • the application provides an automotive electrical device that comprises a first interface with a first load dump protection device and a second interface with a second load dump protection device.
  • the second load dump protection device comprises a voltage follower. A first end of the voltage follower is connected to the first load dump protection device, whilst a second end of the voltage follower is connected to the second interface.
  • a further device can be connected to the first device in such a way that the surge protection of the first device is also operable and active for the further device.
  • An electrical current limiter can be provided in a power supply to the further device for protecting the surge protection of the first device from being overloaded in a case of a power surge.
  • a maximum limit of the electrical current limiter is big enough such that the desired power supply for the further device is not clamped during normal operation.
  • the automotive electrical device relates to an automobile or vehicle.
  • the automobile or vehicle provides transportation means on wheels.
  • the first interface as well as the second interface support transmission of electrical signals between electrical circuits of the first interface and an external circuitry and between electrical circuits of the second interface and other external circuitry.
  • the first interface and the second interface can be subjected to load dumps, which occur when an electrical connection of a main power source of the automobile, such as a battery, is suddenly disconnected.
  • the battery stores chemical energy for conversion to electrical energy.
  • the load dumps are forms of an energy surges that are observed as an excessive high voltage or an excessive high electrical current.
  • the energy surges can cause damage to hardware that receives the energy surges.
  • the main power source generates an electrical current or a certain voltage or electrical potential.
  • the first load dump protection device and the second load dump protection device act to protect the first interface and the second interface.
  • the protection works by limiting a voltage or electrical current surge at its respective terminals to a predetermined maximum value. An unprotected interface can be damaged by an excessive high voltage or electrical current. An energy surge of the load dump is channeled to the first load dump protection device.
  • the voltage follower can channel a load dump at the second interface to the first load dump protection device.
  • the voltage follower can comprise a diode. An anode of the diode can be connected with the second interface whilst a cathode of the diode is connected with the first load dump protection device.
  • a voltage at one end of the voltage follower is presented to another end of the voltage follower.
  • a voltage at an anode of the diode is presented at a cathode of the diode with a negligible voltage drop across the diode.
  • the position of the diode allows a voltage surge of a load dump at the second interface to be presented to the first load dump protection device.
  • the first load dump protection can then act to limit this voltage surge. In this way, the second interface is protected against hardware damage.
  • the second load dump protection device can comprise an electrical current limiter.
  • the electrical current limiter can be provided in series with the voltage follower, in series with the second interface, or between the power supply to the first interface and the second interface.
  • the electrical current limiter can comprise a thermistor.
  • the electrical current limiter limits an electrical current that is flowing through the electrical current limiter from exceeding a predetermined maximum value for protecting hardware against damage.
  • the electrical current limiter that is provided in series with the voltage follower protects the voltage follower from an excessive high electrical current.
  • the protected voltage follower can be smaller as it does not need to handle the excessive high electrical current. A smaller voltage follower can be translated to lower cost.
  • the electrical current limiter that is provided in series with the second interface protects the second interface against an excessive electrical current.
  • the electrical current limiter that is placed between the power supply of the second interface and the second interface protects the second interface against an excessive high electrical current of the power supply.
  • a thermistor resistance increases significantly as a thermistor electrical current that flows through its terminals reaches a certain maximum value. The increased resistance acts to limit the flow of thermistor electrical current. In this manner, the thermistor acts as an electrical current limiter.
  • the automotive electrical device can comprise a voltage sensing device.
  • the voltage sensing device can be connected to the second interface or the first interface for diagnosing the respective first or the second interface.
  • the voltage sensing device can comprise a resistor divider.
  • the voltage sensing device can be connected to an input port of a main processor of the automobile.
  • the main processor has a central processing unit (CPU) with at least one input port.
  • the voltage sensing device provides output voltages of the first interface or of the second interface for reading by another device, such as the main processor.
  • the resistor divider provides voltages with reduced values so the reduced voltages for reading by other devices.
  • the input port of the main processor receives the reduced voltages for processing by the CPU.
  • the voltages provide an indication of diagnostic states of the first interface or of the second interface.
  • the diagnostic states include electrical fault states, such as an electrical short circuit or an electrical open circuit. For example, a high voltage value can indicate a load dump state whilst a low voltage value can indicate an electrical short state.
  • the first load dump protection device can comprise a voltage clamping diode or a high-side driver with a load dump protector. Other forms of the first load dump protection device are possible.
  • the first load dump protection device can also comprise a crowbar circuit, a metal oxide varistor, or a SCR (silicon controlled rectifier).
  • the voltage clamping diode prevents a voltage that is present between its terminals from exceeding a predetermined maximum value by controlling a flow of an electrical current through its terminals.
  • the voltage clamping diode can be positioned such that the voltage clamping diode prevents an incoming voltage of the first interface from reaching an excessive high level that can cause hardware damage to the first interface.
  • the high-side driver can provide electrical power supply to an electronic component.
  • the load dump protector has diodes that act as switches to prevent voltages at a terminal of the high-side driver from exceeding a predetermined maximum value.
  • the high-side driver can be positioned such that the high-side driver prevents an excessive high voltage from being presented to the first interface.
  • the automotive electrical device can further comprise a third interface with a third load dump protection device.
  • the third load dump protection device comprises a further voltage follower. A first end of the further voltage follower is connected to the first load dump protection device whilst a second end of the further voltage follower is connected to the third interface.
  • At least one other interface can be connected to the first load dump protection device.
  • the at least one other interface is provided here, in the form of the third interface with the third load dump protection device.
  • An operation of the third load dump protection device may generate a load dump.
  • the third load dump protection device in cooperation with the first load dump protection device can protect the third interface against the load dump.
  • the further voltage follower can channels a load dump at the third interface to the first load dump protection device.
  • the further voltage follower can comprise a diode. An anode of the diode can be connected with the third interface and a cathode of the diode is connected with the first load dump protection device.
  • An output of the second interface can be is connected to the third interface.
  • the third load dump protection device with the first load dump protection device channels the load dump away from the second interface and the third interface.
  • the electrical device advantageously uses simple and low cost parts.
  • the electrical device avoids duplication of large clamping diodes and can avoid having an integrated high-side driver part.
  • the automotive on-board electric power system comprises at least one electrical device, a first power source device with a first power supply terminal, and a second power source device with a second power supply terminal.
  • the first power supply terminal is connected with the first load dump protection device whilst the second supply terminal is connected with the second load dump protection device.
  • the first power source device and the second power source device provide the electrical device with different power supplies for different electrical device functions, such as air conditioning and ignition.
  • the power supplies generate electrical currents at certain voltages.
  • the electrical device may have different power supplies requirement.
  • the electrical device may have an ignition system that requires a power supply with a high maximum electrical current rating and an entertainment system that requires a power supply with a lower maximum electrical current rating.
  • the first power source device and the second power source device can be connected to a power supply unit.
  • the power supply unit can be in the form of a battery.
  • the vehicle can comprise a main processor that is connected to a voltage sensing device.
  • a method of providing power to an electrical automotive device with a first interface and with a second interface comprises a step of monitoring the first interface for a first load dump and protecting the first interface by channeling the first load dump to a power sink.
  • the method also comprises a step of monitoring the second interface for a second load dump and of protecting the second interface by channeling the second load dump to the power sink.
  • the power sink act as an electrical ground, which can sink or receive an electrical current with a negligible change or no change of electrical potential of the electrical ground.
  • the monitoring can be done for an excessive high voltage of the load dump or for an excessive high electrical current of the load dump.
  • the channeling of the excessive high current of the first load dump into the power sink diverts the first load dump away from the first interface.
  • the channeling of the excessive high current of the second load dump into the power sink diverts the second load dump away from the second interface. In this way, the first interface and the second interface are protected against hardware damage.
  • the step of channeling the second load dump from the second interface to the first interface can comprise the step of limiting an electrical current which is caused by the channeling of the second load dump.
  • a step of limiting an electrical current of the second interface can also be provided.
  • the step of limiting provides further protection for the second interface against the load dump.
  • the limiting of the electrical current can be performed by a thermistor.
  • Fig. 1 illustrates an automotive electrical system
  • Fig. 2 illustrates a first electrical interface protection circuit of the automotive electrical system of Fig. 1,
  • FIG. 3 illustrates a second electrical interface protection circuit of the automotive electrical system of Fig. 1,
  • Fig. 4 illustrates a third electrical interface protection circuit of the automotive electrical system of Fig. 1,
  • Fig. 5 illustrates the third electrical interface protection circuit of Fig. 4 with a resistor divider
  • FIG. 6 illustrates an embodiment of the third electrical interface protection circuit of
  • Fig. 7 illustrates the third electrical interface protection circuit of Fig. 4 with a fourth electrical interface protection circuit
  • Fig. 8 illustrates an embodiment of the third electrical interface protection circuit with the fourth electrical interface protection circuit of Fig. 7.
  • Fig. 1 shows an automotive electrical system 10.
  • the automotive electrical system 10 includes a battery 11 as well as a plurality of systems 12 that are connected to the battery 11 via a switch 13 and a switch 14.
  • a first system 15, a second system 16, and other systems 18 of the plurality of systems 12 are connected in parallel to the battery 11.
  • a third system 17 is connected to the battery 11 through the first system 15 and the second system 16.
  • the battery 11 has a positive terminal 21 and a negative terminal 22.
  • the negative terminal 22 is connected via the switch 14 to an incoming ground terminal 24 of the first system 15, to an incoming ground terminal 25 of the second system 16, and to an incoming ground terminal 26 of the other systems 18.
  • the first system incoming ground terminal 24 is internally connected to an outgoing ground terminal 28 of the first system 15, which is also connected to a main ground terminal 29 of the third system 17.
  • the second system incoming ground terminal 25 is internally connected to an outgoing ground terminal 32 of the second system 16, which is also connected to an auxiliary ground terminal 33 of the third system 17.
  • the positive terminal 21 is connected via the switch 13 to an incoming power supply terminal 35 of the first system 15, to an incoming power supply terminal 36 of the second system 16, and to an incoming power supply terminal 37 of the other systems 18.
  • the first system incoming power supply terminal 35 is internally connected to an output power terminal 40 of the first system 15 that is connected to a main power supply terminal 41 of the third system 17. In this manner, a main power supply is provided to a main interface of the third system 17 by the first system 15.
  • the second system incoming power supply terminal 36 is internally connected to an outgoing power supply terminal 43 of the second system 16, which is connected to an auxiliary power supply terminal 44 of the third system 17.
  • an auxiliary power supply is provided to an auxiliary interface of the third system 17 by the second system 16.
  • Electrical components are provided in the first system 15, in the second system 16, in the third system 17, and in the other systems 18. These electrical components are electrically connected and/or mechanically connected to provide certain functions of the automotive electrical system 10. Examples of the functions are vehicle temperature sensor and steering wheel position sensor.
  • the electrical components form electrical circuits that reside in the first system 15, in the second system 16, in the third system 17, and in the other systems 18.
  • the electrical components are not shown in Fig. 1.
  • the electrical circuits include interfaces for handling electrical signals that are external to the first system 15, to the second system 16, to the third system 17, and to the other systems 18.
  • the interfaces comprise protection circuits for protecting the electrical circuits against transient electrical current or voltages.
  • the battery 11 provides a power supply via the switches 13 and 14 to the first system 15, to the second system 16, to the third system 17, and to the other systems 18.
  • the power supply sources an electrical current via the positive terminal 21 and it sinks or receives the electrical current by the negative terminal 22.
  • An alternator of the automotive electrical system 10 may provide power to the battery 11 and it may charge up the battery 11.
  • the battery 11 has an operating voltage of about 12.6 volts as well as charging up voltages between 13.2 volts and 14.4 volts.
  • the first system 15 and the second system 16 do not perform preconditioning of the battery power supply. Without the preconditioning of the battery power supply, an electrical surge at the first system 15 or the second system 16 can be channelled to the third system 17.
  • the electrical surge can be in the form of an excessive high electrical current or an excessive high voltage.
  • the third system auxiliary power supply terminal 44 and the third system main power supply terminal 41 provide electrical connections for supplying electrical power supply to electrical circuits of the third system 17.
  • a electrical power supply that is required by the third system main power supply terminal 41 is different from an electrical power supply that is required the third system auxiliary power supply terminal 44.
  • the difference is in terms of voltage or electrical current rating. Because of the difference, the third system auxiliary power supply terminal 44 and the third system main power supply terminal 41 cannot be easily combined to form a single terminal.
  • An electrical connection point for supplying electrical power supply to the electrical circuits of the first system 15 is provided by the first system incoming power supply terminal 35.
  • the second system incoming power supply terminal 36 provides an electrical connection point for supplying electrical power supply to the electrical circuits of the second system 16.
  • the incoming power supply terminal 37 provides an electrical connection point for supplying electrical power supply to the electrical circuits of the other systems 18.
  • the first system incoming ground terminal 24 provides an electrical ground connection point for electrical circuits that are within the first system 15.
  • the second system incoming ground terminal 25 and the other systems incoming ground terminal 26 provide an electrical ground connection points for electrical circuits that are within the second system 16 and the other systems 18 respectively.
  • the third system main ground terminal 29 and the third system auxiliary ground terminal 33 provide an electrical ground connection points for electrical circuits within the third system 17.
  • the switch 13 and switch 14 are intended to make or to break electrical connection between the battery 11 and the plurality of the systems 12.
  • FIGs. 2 to 8 show several embodiments of protection device against load dumps. Figs.
  • FIGs. 2 to 5 depict several embodiments of the third system 17 of Fig. 1 that is connected to the first system 15 of Fig. 1 and to the second system 16 of Fig. 1.
  • Fig. 2 illustrates a first electrical interface protection circuit 45 of the third system 17.
  • the first electrical interface protection circuit 45 has a main protection circuit 46 and an auxiliary protection circuit 47.
  • the main protection circuit 46 is connected to a main interface 51 of the third system 17 whilst the auxiliary protection circuit 47 is connected to an auxiliary interface 53 of the third system 17.
  • the main protection circuit 46 includes an inductor Ll, a capacitor Cl, and a clamping diode Dl.
  • a first end of the inductor Ll is connected to the third system main power supply terminal 41 whilst a second end of the inductor Ll is connected to a first end of the capacitor Cl thereby forming a node 48.
  • a second end of the capacitor Cl is connected to the third system main ground terminal 29.
  • a cathode of the clamping diode Dl is connected to the node 48 whilst an anode of the clamping diode Dl is connected to the third system main ground terminal 29.
  • the node 48 is connected to the main interface 51 of the third system 17.
  • the clamping diode Dl is also called a voltage clamping diode.
  • the auxiliary protection circuit 47 comprises a capacitor C2 and a clamping diode D2.
  • a first end of the capacitor C2 is connected to the third system auxiliary power supply terminal 44 whilst a second end of the capacitor C2 is connected to the third system auxiliary ground terminal 33.
  • a cathode of the clamping diode D2 is connected to the third system auxiliary power supply terminal 44 whereas an anode of the clamping diode D2 is connected to the third system auxiliary ground terminal 33.
  • the third system auxiliary power supply terminal 44 is also connected to the auxiliary interface 53.
  • the clamping diode D2 is also called a voltage clamping diode.
  • the main protection circuit 46 and the auxiliary protection circuit 47 protect the main interface 51 and the auxiliary interface 53 against load dumps.
  • the main protection circuit 46 receives a mainstream power supply 57 from the first system 15 whereas the auxiliary protection circuit 47 receives a non-mainstream power supply 58 from the second system 16.
  • the mainstream power supply 57 provides power for main electrical circuits of the third system 17 and it has a maximum current rating of 10 A (ampere).
  • the non-mainstream power supply 58 provides power supply for special electrical circuits of the third system 17 and it has a maximum electrical current rating of 5 A.
  • the clamping diode Dl with the clamping diode D2 protects the main interface 51 and the auxiliary interface 53 against hardware damage of a load dump.
  • the load dump has an energy surge that can be observed as an excessive high voltage or an excessive high electrical current.
  • a load dump that is present in the mainstream power supply 57 would act to increase a voltage of the cathode of the clamping diode Dl.
  • the clamping diode Dl limits the cathode voltage from exceeding a maximum value of typical 18.5 or 26.5 volts by channelling an electrical current of the mainstream power supply 57 from its cathode to its anode. The maximum value is also called a breakdown voltage. No electrical current effectively flows from the cathode of the clamping diode Dl to its anode, in normal situations.
  • a cathode voltage of the clamping diode Dl is also greater than an anode voltage of the clamping diode Dl by less than the breakdown voltage.
  • the size of the clamping diode D 1 is sufficiently large to handle a breakdown electrical current, which can be large.
  • the energy surge of the load dump is diverted into the anode of the clamping diode Dl and away from the main interface 51. In this way, the main interface 51 is protected against hardware damage of the load dump into the third system 17.
  • the clamping diode D2 in a similar manner protects the auxiliary interface 52 against a load dump that is present in the non-mainstream power supply 58.
  • the inductor Ll with the capacitor Cl is intended for filtering of the mainstream power supply 58.
  • the capacitor C2 is used for electrical noise rejection and for ESD (electrostatic discharge) protection.
  • This embodiment advantageously provides protection for the third system 17 against load dumps.
  • Fig. 3 illustrates a second electrical interface protection circuit 49.
  • the second electrical interface protection circuit 49 includes the main protection circuit 46 of Fig. 2 and an auxiliary protection circuit 50.
  • the auxiliary protection circuit 50 comprises a capacitor C2' and a high-side driver
  • a first end of the capacitor C2' is connected to the third system auxiliary power supply terminal 44 whereas a second end of the capacitor C2' is connected to the third system auxiliary ground terminal 33.
  • a first end of the high-side driver 52 is connected to the third system auxiliary power supply terminal 44 whilst a second end of the high- side driver 52 is connected to the auxiliary interface 53 of the third system 17.
  • the high-side driver 52 includes an integrated load dump protector, which has active switches that turn off when a load dump occurs.
  • the active switches can be in the form of clamping diodes or of zener diodes.
  • the integrated load dump protector is not shown in the figure.
  • the high-side driver 52 provides an electrical power supply for a load.
  • the integrated load dump protector protects the auxiliary interface 53 against a load dump by isolating the auxiliary interface 53 from the load dump via turning off the active switches.
  • the zener diode is also called an avalanche breakdown diode.
  • the zener diode permits an electrical current to flow in a forward direction when voltages across its terminal are below a certain breakdown voltage and an electrical current to flow in the reverse direction if the voltage across its terminal is larger than the certain breakdown voltage.
  • Fig. 4 depicts a third electrical interface protection circuit 54.
  • the third electrical interface protection circuit 54 includes the main protection circuit 46 of Fig. 2 or 3 as well as an auxiliary protection circuit 55.
  • the auxiliary protection circuit 55 is connected to an auxiliary interface 53 of the third system 17.
  • the auxiliary protection circuit 55 includes a capacitor C2", a thermistor Nl, and a voltage follower diode D3.
  • a first end of the capacitor C2" is connected to the third system auxiliary power supply terminal 44 whereas a second end of the capacitor C2" is connected to the third system auxiliary ground terminal 33 and to an electrical ground 62 .
  • a first end of the thermistor Nl is connected to the third system auxiliary power supply terminal 44 .
  • a second end of the thermistor Nl is connected to an anode of the voltage follower diode D3 thereby forming a node 56.
  • the node 56 is connected to the auxiliary interface 53.
  • the cathode of the voltage follower diode D3 is connected to the cathode of the clamping diode Dl of the main protection circuit 46.
  • the anode of the clamping diode Dl is connected to an electrical ground 63.
  • the auxiliary protection circuit 55 transfers a power of a non mainstream power supply 58 from the second system 16 to the auxiliary interface 53 and it protects the auxiliary interface 53 from load dump.
  • the main protection circuit 46 transfers a power of a mainstream power supply 57 from the first system 15 to the main interface 51 and it protects the main interface 51 against a load dump.
  • the thermistor Nl and the voltage follower diode D3 are intended to replace the large clamping diode D2 of Fig. 2 or the high-side driver 52 of Fig. 3.
  • the thermistor Nl acts as an electrical current limiter and it prevents an excessive high electrical current from flowing through it. A load dump can generate excessive high electrical current. This action protects the voltage follower diode D3 against an over-current.
  • the over-current is a condition of an electrical circuit wherein an electrical current in an electrical circuit exceeds a rated electrical current capacity of the electrical circuit or of an equipment that is connected to the electrical circuit.
  • a maximum limit of the thermistor Nl is large enough such that it does not limit an input electric current to the auxiliary interface 53 during normal operations.
  • the input electrical current of the auxiliary interface 53 flows through the thermistor Nl.
  • a resistance of the thermistor Nl varies with the temperature of the thermistor Nl.
  • the thermistor Nl is of a PTC (positive temperature coefficient) type, wherein a resistance of the thermistor Nl increases with higher thermistor temperature.
  • a thermistor current flows through the thermistor Nl.
  • the value of the thermistor current is less than maximum current rating of the thermistor Nl.
  • the thermistor current generates heat that is dissipated by the thermistor Nl.
  • a load dump a high electrical current flow through the thermistor Nl and heat that is generated by the thermistor Nl is not fully dissipated by the thermistor Nl. This causes the temperature of the thermistor Nl to increase significantly and correspondingly the resistance of the thermistor Nl to increase significantly. This in turn causes the thermistor current to be reduced significantly.
  • the voltage follower diode D3 in co-operation with the clamping diode Dl acts to clamp the voltage of node 56 to a certain maximum value.
  • the voltage follower diode D3 also prevents back flow of voltage and electrical current that is greater than parasitic to a specific interface during normal operations.
  • a package size of the voltage follower diode D3 needs not be large. Forward electrical current of the voltage follower diode D3 is not large as the forward current of the clamping diode as it is limited by the current limiting function of the thermistor Nl. Thus, the package size of the voltage follower diode D3 does not need be large to support a large current. As the size of the voltage follower diode D3 is small, its cost is also less. Moreover, the voltage follower D3 is able to withstand a high reverse voltage. The reverse voltage occurs when a voltage of the cathode of the voltage follower D3 that is greater than a voltage of the anode of the voltage follower D3. The high reverse voltage does not cause an electrical current to flow from the cathode of the voltage follower D3 to the anode of the voltage follower D3.
  • the electrical ground 62 and the electrical ground 63 act to sink electrical current in a manner that its electrical potential does not change.
  • an input voltage at the third system auxiliary power supply terminal 44 is lower than a mainstream voltage of the third system main power supply terminal 41 due to voltage drop across the voltage follower diode D3.
  • the voltage at the node 56, which is connected to the auxiliary interface 53, is almost the same as the input voltage.
  • the thermistor resistance is low and it does not significantly increase an input impedance of the auxiliary interface 53.
  • the voltage follower diode D3 isolates the auxiliary interface 53 from the high voltage of the load dump.
  • the voltage follower diode D3 is able to withstand the high voltage that is present at its cathode and it does not allow the high voltage to cause an electrical current to flow from its cathode to its anode. In this manner, the auxiliary interface 53 is isolated from the load dump and is protected from hardware damage.
  • the clamping diode Dl channels an electrical current of the load dump such that its cathode voltage does not exceed the clamping voltage Vc.
  • the electrical current is channelled from the anode of the voltage follower diode D3 to cathode of the voltage follower diode D3, to the cathode of the clamping diode Dl, to the anode of the clamping diode Dl, and to the electrical ground 63. Effectively, a short-circuit from the anode of the voltage follower diode D3 to the electrical ground 63 is thereby created. In this manner, an energy surge of the load dump is channelled into the electrical ground 63 and away from the auxiliary interface 53. The auxiliary protection circuit 55 is thus protected against the load dump.
  • the channelling causes a thermistor current of the thermistor
  • the thermistor Nl is, in this electrical sense, in series with the voltage follower D3.
  • the amount of thermistor current increases and it does not exceed a maximum current rating of the thermistor Nl.
  • the voltage of node 56 which represent an input voltage of the auxiliary interface 53, is limited to a sum of clamping voltage Vc of the clamping diode Dl and of voltage follower diode voltage V_d3, wherein the follower diode voltage V_d3 represents a voltage drop across the voltage follower diode D3.
  • the thermistor current reaches the maximum current rating of the thermistor Nl.
  • the heat generated by the thermistor current is not fully dissipated by the thermistor Nl.
  • This causes the thermistor temperature to increase significantly.
  • the thermistor resistance also increases significantly. The increased thermistor resistance acts to limit the flow of the thermistor current. Later thermistor resistance is increased significantly and the flow of the thermistor current is also reduced significantly.
  • the input voltage of the auxiliary interface 53 is clamped to a sum of the clamping voltage Vc and of a voltage across the voltage follower D3, during the normal operation.
  • the auxiliary protection circuit 55 can also be duplicated for other interfaces of the third system 17.
  • the auxiliary protection circuit 55 can also be adapted to provide different current limits for different interfaces.
  • the different current limits can be implemented using different thermistor Nl that has different current limit rating and using corresponding different voltage follower diode D3. It is believed that this adaption is easier than selecting different types of high- side driver.
  • the embodiment provides a low cost electrical circuit with protection level that is similar to other types of protection circuit.
  • the embodiment advantageously avoids the use of large components, such as clamping diodes or high-side drivers.
  • the embodiment allows voltage-clamping action to be performed by one large component, instead of several large components.
  • the maximum current of the auxiliary interface 53 is limited by the thermistor Nl.
  • the size of the clamping diode D3 need not be large to handle energy surges.
  • the auxiliary protection circuit 55 has a reduced size.
  • a PCB (printed circuit board) using the auxiliary protection circuit 55 would have a reduced PCB real estate.
  • the size of the thermistor is relatively small.
  • the voltage follower diode D3 which routes a voltage at its anode to its cathode and to the clamping diode Dl, can relatively small as compared to a clamping diode. It is believed that a clamping diode costs about 10 times more than a cost of the auxiliary protection circuit 55. This thereby results in a reduction of a BOM (bill of material) of the overall system.
  • a current limiter such as a thermistor, is placed in series with the voltage follower diode D3 and is placed between the node 56 and the node 48.
  • the current limiter acts to prevent excessive electrical current from reaching the voltage follower diode D3.
  • the current limiter can be provided in place of the thermistor Nl or in addition to the thermistor Nl.
  • Fig. 5 shows the third electrical interface protection circuit 54 of Fig. 4 with a resistor divider 60.
  • the resistor divider 60 provides a diagnostic capability for the auxiliary protection circuit 55, which is shown in Fig. 4 description.
  • the resistor divider 60 has a first resistor Rl and a second resistor R2. A first end of the first resistor Rl is connected to an electrical ground 80 whereas a second end of the first resistor Rl is connected to a first end of the second resistor R2 thereby forming a node 61.
  • the node 61 is connected to an analogue to digital conversion (ADC) port 79 of a main processor 78.
  • ADC analogue to digital conversion
  • the second end of the second resistor R2 is connected to the node 56 that is shown in Fig. 4 description.
  • the resistor divider 60 provides diagnostic capability to detect occurrence of a load dump at the auxiliary interface 53.
  • the resistive divider 60 provides a stepped down voltage or a reduced voltage of the node 56.
  • the reduced voltage can be used to detect a battery short or a ground short at the auxiliary interface 53 during normal operations.
  • the main processor 78 uses the ADC port 79 to obtain a voltage reading of the node 61.
  • the voltage reading provides an indication as to whether a voltage-clamping step or a current- limiting step of a load dump has occurred.
  • the third system 17 can then respond with appropriate actions to the indication.
  • the voltage reading at the main processor 78 will be a zero. If the voltage- clamping step occurs, the voltage reading would be scaled down a sum of a clamping voltage Vc and a follower diode voltage V_d3.
  • the resistor divider 60 provides a low cost diagnostic capability. It is believed that the diagnostic capability costs tens times less that a similar diagnostic capability that is provided by a high-side driver.
  • Fig. 6 shows an embodiment of the third electrical interface protection circuit of Fig. 5. The embodiment illustrates an application of the third electrical interface protection circuit in a vehicle.
  • Fig. 6 depicts an vehicle 69 with the third system 17 that is provided here as a controller, with the second system 16 that is provided here as a temperature sensor, and with the first system 15 that is provided here as a steering wheel motor.
  • the vehicle 69 comprises a steering wheel system 70.
  • the steering wheel system 70 includes a steering wheel 71 that is connected to a shaft 72.
  • the shaft 72 is connected to a steering mechanism of a wheel 74.
  • a voltage reading 76 of the resistor divider 60 of the controller 17 is transmitted a digital conversion (ADC) port 79 of the main processor 78.
  • ADC digital conversion
  • the controller 17 receives a temperature electrical signal 65 from the temperature sensor 16. The controller 17 also receives a position signal 67 from the steering wheel motor 15.
  • the vehicle 69 provides a mode of transportation.
  • the vehicle 69 can be in the form of an automobile.
  • the temperature sensor 16 generates temperature readings of a combustion engine of the vehicle 69 and it sends the temperature readings to the controller 17 for managing the combustion engine.
  • the steering wheel motor 15 records the steering wheel positions and it sends the steering wheel positions to the controller 17 also for managing the combustion engine.
  • Fig. 7 shows a fourth electrical interface protection circuit 85 of a fourth system 86.
  • the fourth system 86 is connected to the third system 17 of Fig. 4.
  • the fourth electrical interface protection circuit 85 includes a second auxiliary protection circuit 88 and a second auxiliary interface 89 that is connected to the second auxiliary protection circuit 88.
  • the second auxiliary protection circuit 88 comprises a second thermistor Nl' and a second voltage follower diode D3'.
  • One end of the second thermistor Nl' is connected to an outgoing power supply terminal 92 of the auxiliary interface 53 of Fig. 4.
  • Another end of the second thermistor Nl' is connected to an anode of the second voltage follower diode D3' thereby forming node 92 and to the second auxiliary interface 89.
  • a cathode of the second voltage follower diode D3' is connected to the node 48 of Fig. 4.
  • the second auxiliary protection circuit 88 receives a second non-mainstream power supply 95 from the third system 17.
  • the second non-mainstream power supply 95 provides a power supply for electrical circuits of the fourth system 86 via the thermistor Nl '.
  • the second auxiliary protection circuit 88 channels a load dump at its terminal to the clamping diode Dl of the main protection circuit 46 of Fig. 4.
  • An operation of the second auxiliary interface 89 may generate the load dump.
  • the load dump is channelled from the anode of the second voltage follower diode D3' to the cathode of the second voltage follower diode D3', to the anode of the clamping diode Dl, to the anode of the clamping diode Dl, and to the electrical ground 63 of Fig. 4.
  • the second thermistor Nl' limits an electrical current flowing through its terminal during the load dump.
  • Fig. 8 depicts an embodiment of Fig. 7 to provide a more concrete example of the Fig. 7.
  • Fig. 8 shows an ignition switch 100 of an automotive.
  • the ignition switch 100 is connected to the car battery 11 of Fig. 1 by a wire 112.
  • a wire 110 connects the ignition switch 100 to a fan control 102 that is provided by the third system 17.
  • the fan control 102 is connected to a fan 104 that is provided by the fourth system 86.
  • a wire 111 connects the ignition switch 100 to an air-conditioning compressor 103 that is provided by the third system 17.
  • the voltage follower diode D3 connects a load-dump protection circuit of the fan control 102 to a load-dump protection circuit of the air-conditioning compressor 103.
  • the voltage follower diode D3' connects a load-dump protection circuit of the fan 104 to the load- dump protection circuit of the air-conditioning compressor 103.
  • the ignition switch 100 is intended for selecting a run state, a standby state, and an off state of the automobile.
  • the voltage follower diode D3 acts to channel a load-dump at the load-dump protection circuit of the fan control 102 to the load-dump protection circuit of the air- conditioning compressor 103. Likewise, t he voltage follower diode D3' acts to channel a load-dump at the load-dump protection circuit of the fan 104 to the load-dump protection circuit of the air-conditioning compressor 103.
  • the fan control 102 receives the non-mainstream power supply 58 from the car battery 11 via the ignition switch 100.
  • An engine of the automotive is not operating or running whilst the car battery 11 does not receive power from an alternator of the automotive.
  • the fan control 102 provides the non-mainstream power supply 95 to the fan 104, which may be running depending on a setting of the fan control 102.
  • the fan control 102 receives the non-mainstream power supply 58 from the car battery 11, in the run state.
  • the engine is also running for the alternator to charge up the car battery 11.
  • the fan control 102 also provides the non-mainstream power supply 95 to the fan 104 whilst the air-conditioning compressor 103 receives the mainstream power supply 57.
  • the fan control 102 and the air-conditioning compressor 103 may receive load dumps via the wire 110 and the wire 111 respectively.
  • the fan 104 may also generate a load dump via due to its high inductance.
  • the fan control 102, the air-conditioning compressor 103, and the fan 104 have load dump protection circuits for protecting against the load dumps.
  • the protection circuit of the fan control 102 and the protection circuit of the fan 104 channel surge energy of their respectively load dumps to the protection circuit of the air-conditioning compressor 103 in a manner described earlier.
  • the above embodiments are configured such that an Ilimit (maximum current rating of the thermistor Nl) is greater than an Imax (maximum current rating of the auxiliary interface 53).
  • An Iforward maximal forward current of the diode D3 is greater than the Ilimit (maximum current rating of the thermistor Nl).
  • a Vd3 voltage drop of voltage follower diode D3) is greater than a VIl (voltage drop across inductor Ll).
  • the resistor divider 60 of Fig. 5 detects the presence of a load dump using voltages and it is does not exceed a maximum input voltage of the main processor.
  • the above embodiments provide electrical protection circuits that protect against a load dump of multiple interfaces of an automobile system by channeling the load dump into a single interface.
  • the electrical protection circuits protect the multiple interfaces against large electrical currents of the load dump by disconnecting the multiple interfaces from the large electrical current and against high voltages of the load dump by clamping the high voltages.
  • the electrical protection circuit is implemented at low cost by avoiding duplication of large clamping diodes and by providing an alternative to integrated high- side driver components.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

An automotive electrical device comprises a first interface (51 ) with a first load dump protection device (46), and a second interface (53) with a second load dump protection device (55). The second load dump protection device (55) comprises a voltage follower (D3). A first end of the voltage follower (D3) is connected to the first load dump protection device (46) and a second end of the voltage follower (D3) is connected to the second interface (53).

Description

Description Protection against load dump on multiple automobile interfaces
[1] This application relates to a protection against load dump. In particular, this application relates to the load dump at automobile interfaces.
[2] US 6 650 521 B2 discloses a protection circuit for a load dump condition that employs a voltage division circuit to reduce voltage applied to a system under test (SUT). This allows the applied voltage to be reduced to permit a use of a lower voltage rating for power MOSFETs (metal-oxide- semiconductor field-effect transistor) in the SUT. The voltage division circuit employs a resistor and a switch. The switch is closed at voltages higher than a given value at terminals of the SUT and it is opened when the applied voltage reduces below the given value.
[3] US 6 346 797 Bl discloses an alternator system having an AC (alternating current) machine that includes a switched-mode rectifier operating at a duty cycle that is based upon at least one of an EMF (electromagnetic field), a frequency, or a speed of operation of the AC machine. The switched-mode rectifier operates such that the alternator system provides a load match that results in output power levels that are relatively high compared with output power levels of conventional alternator systems.
[4] The application provides an automotive electrical device that comprises a first interface with a first load dump protection device and a second interface with a second load dump protection device. The second load dump protection device comprises a voltage follower. A first end of the voltage follower is connected to the first load dump protection device, whilst a second end of the voltage follower is connected to the second interface.
[5] One of the basic thoughts of the application is that the automobile usually already has a first device with an interface that has a reliable and therefore expensive surge protection. A further device can be connected to the first device in such a way that the surge protection of the first device is also operable and active for the further device.
[6] An electrical current limiter can be provided in a power supply to the further device for protecting the surge protection of the first device from being overloaded in a case of a power surge. A maximum limit of the electrical current limiter is big enough such that the desired power supply for the further device is not clamped during normal operation.
[7] The automotive electrical device relates to an automobile or vehicle. The automobile or vehicle provides transportation means on wheels. The first interface as well as the second interface support transmission of electrical signals between electrical circuits of the first interface and an external circuitry and between electrical circuits of the second interface and other external circuitry. The first interface and the second interface can be subjected to load dumps, which occur when an electrical connection of a main power source of the automobile, such as a battery, is suddenly disconnected. The battery stores chemical energy for conversion to electrical energy. The load dumps are forms of an energy surges that are observed as an excessive high voltage or an excessive high electrical current. The energy surges can cause damage to hardware that receives the energy surges. The main power source generates an electrical current or a certain voltage or electrical potential.
[8] The first load dump protection device and the second load dump protection device act to protect the first interface and the second interface. The protection works by limiting a voltage or electrical current surge at its respective terminals to a predetermined maximum value. An unprotected interface can be damaged by an excessive high voltage or electrical current. An energy surge of the load dump is channeled to the first load dump protection device.
[9] The voltage follower can channel a load dump at the second interface to the first load dump protection device. The voltage follower can comprise a diode. An anode of the diode can be connected with the second interface whilst a cathode of the diode is connected with the first load dump protection device.
[10] A voltage at one end of the voltage follower is presented to another end of the voltage follower. During normal operations, a voltage at an anode of the diode is presented at a cathode of the diode with a negligible voltage drop across the diode. The position of the diode allows a voltage surge of a load dump at the second interface to be presented to the first load dump protection device. The first load dump protection can then act to limit this voltage surge. In this way, the second interface is protected against hardware damage.
[11] The second load dump protection device can comprise an electrical current limiter.
The electrical current limiter can be provided in series with the voltage follower, in series with the second interface, or between the power supply to the first interface and the second interface. The electrical current limiter can comprise a thermistor.
[12] The electrical current limiter limits an electrical current that is flowing through the electrical current limiter from exceeding a predetermined maximum value for protecting hardware against damage.
[13] The electrical current limiter that is provided in series with the voltage follower protects the voltage follower from an excessive high electrical current. In addition, the protected voltage follower can be smaller as it does not need to handle the excessive high electrical current. A smaller voltage follower can be translated to lower cost.
[14] Similarly, the electrical current limiter that is provided in series with the second interface protects the second interface against an excessive electrical current. In particular, the electrical current limiter that is placed between the power supply of the second interface and the second interface protects the second interface against an excessive high electrical current of the power supply.
[15] A thermistor resistance increases significantly as a thermistor electrical current that flows through its terminals reaches a certain maximum value. The increased resistance acts to limit the flow of thermistor electrical current. In this manner, the thermistor acts as an electrical current limiter.
[16] The automotive electrical device can comprise a voltage sensing device. The voltage sensing device can be connected to the second interface or the first interface for diagnosing the respective first or the second interface. The voltage sensing device can comprise a resistor divider. The voltage sensing device can be connected to an input port of a main processor of the automobile. The main processor has a central processing unit (CPU) with at least one input port.
[17] The voltage sensing device provides output voltages of the first interface or of the second interface for reading by another device, such as the main processor. The resistor divider provides voltages with reduced values so the reduced voltages for reading by other devices. The input port of the main processor receives the reduced voltages for processing by the CPU.
[18] The voltages provide an indication of diagnostic states of the first interface or of the second interface. The diagnostic states include electrical fault states, such as an electrical short circuit or an electrical open circuit. For example, a high voltage value can indicate a load dump state whilst a low voltage value can indicate an electrical short state.
[19] The first load dump protection device can comprise a voltage clamping diode or a high-side driver with a load dump protector. Other forms of the first load dump protection device are possible. The first load dump protection device can also comprise a crowbar circuit, a metal oxide varistor, or a SCR (silicon controlled rectifier).
[20] The voltage clamping diode prevents a voltage that is present between its terminals from exceeding a predetermined maximum value by controlling a flow of an electrical current through its terminals. The voltage clamping diode can be positioned such that the voltage clamping diode prevents an incoming voltage of the first interface from reaching an excessive high level that can cause hardware damage to the first interface.
[21] The high-side driver can provide electrical power supply to an electronic component.
The load dump protector has diodes that act as switches to prevent voltages at a terminal of the high-side driver from exceeding a predetermined maximum value. The high-side driver can be positioned such that the high-side driver prevents an excessive high voltage from being presented to the first interface.
[22] The automotive electrical device can further comprise a third interface with a third load dump protection device. The third load dump protection device comprises a further voltage follower. A first end of the further voltage follower is connected to the first load dump protection device whilst a second end of the further voltage follower is connected to the third interface.
[23] At least one other interface can be connected to the first load dump protection device.
The at least one other interface, is provided here, in the form of the third interface with the third load dump protection device.
[24] An operation of the third load dump protection device may generate a load dump.
Similar, to the manner described earlier, the third load dump protection device in cooperation with the first load dump protection device can protect the third interface against the load dump.
[25] The further voltage follower can channels a load dump at the third interface to the first load dump protection device. The further voltage follower can comprise a diode. An anode of the diode can be connected with the third interface and a cathode of the diode is connected with the first load dump protection device.
[26] An output of the second interface can be is connected to the third interface. The third load dump protection device with the first load dump protection device channels the load dump away from the second interface and the third interface.
[27] The electrical device advantageously uses simple and low cost parts. The electrical device avoids duplication of large clamping diodes and can avoid having an integrated high-side driver part.
[28] An automotive on-board electric power system is provided by the application. The automotive on-board electric power system comprises at least one electrical device, a first power source device with a first power supply terminal, and a second power source device with a second power supply terminal.
[29] The first power supply terminal is connected with the first load dump protection device whilst the second supply terminal is connected with the second load dump protection device.
[30] The first power source device and the second power source device provide the electrical device with different power supplies for different electrical device functions, such as air conditioning and ignition. The power supplies generate electrical currents at certain voltages. As an example, the electrical device may have different power supplies requirement. The electrical device may have an ignition system that requires a power supply with a high maximum electrical current rating and an entertainment system that requires a power supply with a lower maximum electrical current rating.
[31] The first power source device and the second power source device can be connected to a power supply unit. The power supply unit can be in the form of a battery. The vehicle can comprise a main processor that is connected to a voltage sensing device.
[32] A method of providing power to an electrical automotive device with a first interface and with a second interface is provided by the application. The method comprises a step of monitoring the first interface for a first load dump and protecting the first interface by channeling the first load dump to a power sink. The method also comprises a step of monitoring the second interface for a second load dump and of protecting the second interface by channeling the second load dump to the power sink.
[33] The power sink act as an electrical ground, which can sink or receive an electrical current with a negligible change or no change of electrical potential of the electrical ground. The monitoring can be done for an excessive high voltage of the load dump or for an excessive high electrical current of the load dump. The channeling of the excessive high current of the first load dump into the power sink diverts the first load dump away from the first interface. Similarly, the channeling of the excessive high current of the second load dump into the power sink diverts the second load dump away from the second interface. In this way, the first interface and the second interface are protected against hardware damage.
[34] The step of channeling the second load dump from the second interface to the first interface can comprise the step of limiting an electrical current which is caused by the channeling of the second load dump.
[35] A step of limiting an electrical current of the second interface can also be provided.
The step of limiting provides further protection for the second interface against the load dump. The limiting of the electrical current can be performed by a thermistor.
[36] Fig. 1 illustrates an automotive electrical system,
[37] Fig. 2 illustrates a first electrical interface protection circuit of the automotive electrical system of Fig. 1,
[38] Fig. 3 illustrates a second electrical interface protection circuit of the automotive electrical system of Fig. 1,
[39] Fig. 4 illustrates a third electrical interface protection circuit of the automotive electrical system of Fig. 1,
[40] Fig. 5 illustrates the third electrical interface protection circuit of Fig. 4 with a resistor divider,
[41] Fig. 6 illustrates an embodiment of the third electrical interface protection circuit of
Fig. 5.
[42] Fig. 7 illustrates the third electrical interface protection circuit of Fig. 4 with a fourth electrical interface protection circuit, and
[43] Fig. 8 illustrates an embodiment of the third electrical interface protection circuit with the fourth electrical interface protection circuit of Fig. 7.
[44] Fig. 1 shows an automotive electrical system 10. The automotive electrical system 10 includes a battery 11 as well as a plurality of systems 12 that are connected to the battery 11 via a switch 13 and a switch 14. [45] A first system 15, a second system 16, and other systems 18 of the plurality of systems 12 are connected in parallel to the battery 11. A third system 17 is connected to the battery 11 through the first system 15 and the second system 16.
[46] The battery 11 has a positive terminal 21 and a negative terminal 22.
[47] The negative terminal 22 is connected via the switch 14 to an incoming ground terminal 24 of the first system 15, to an incoming ground terminal 25 of the second system 16, and to an incoming ground terminal 26 of the other systems 18.
[48] The first system incoming ground terminal 24 is internally connected to an outgoing ground terminal 28 of the first system 15, which is also connected to a main ground terminal 29 of the third system 17. Similarly, the second system incoming ground terminal 25 is internally connected to an outgoing ground terminal 32 of the second system 16, which is also connected to an auxiliary ground terminal 33 of the third system 17.
[49] The positive terminal 21 is connected via the switch 13 to an incoming power supply terminal 35 of the first system 15, to an incoming power supply terminal 36 of the second system 16, and to an incoming power supply terminal 37 of the other systems 18.
[50] The first system incoming power supply terminal 35 is internally connected to an output power terminal 40 of the first system 15 that is connected to a main power supply terminal 41 of the third system 17. In this manner, a main power supply is provided to a main interface of the third system 17 by the first system 15.
[51] In a similar manner, the second system incoming power supply terminal 36 is internally connected to an outgoing power supply terminal 43 of the second system 16, which is connected to an auxiliary power supply terminal 44 of the third system 17. In this way, an auxiliary power supply is provided to an auxiliary interface of the third system 17 by the second system 16.
[52] Electrical components are provided in the first system 15, in the second system 16, in the third system 17, and in the other systems 18. These electrical components are electrically connected and/or mechanically connected to provide certain functions of the automotive electrical system 10. Examples of the functions are vehicle temperature sensor and steering wheel position sensor.
[53] The electrical components form electrical circuits that reside in the first system 15, in the second system 16, in the third system 17, and in the other systems 18. The electrical components are not shown in Fig. 1. The electrical circuits include interfaces for handling electrical signals that are external to the first system 15, to the second system 16, to the third system 17, and to the other systems 18. The interfaces comprise protection circuits for protecting the electrical circuits against transient electrical current or voltages. [54] From a functional point of view, the battery 11 provides a power supply via the switches 13 and 14 to the first system 15, to the second system 16, to the third system 17, and to the other systems 18. The power supply sources an electrical current via the positive terminal 21 and it sinks or receives the electrical current by the negative terminal 22. An alternator of the automotive electrical system 10 may provide power to the battery 11 and it may charge up the battery 11. The battery 11 has an operating voltage of about 12.6 volts as well as charging up voltages between 13.2 volts and 14.4 volts.
[55] An energy surge of a load dump occurring at the first system 15 or the second system
16 can be channelled to the third system 17. The first system 15 and the second system 16 do not perform preconditioning of the battery power supply. Without the preconditioning of the battery power supply, an electrical surge at the first system 15 or the second system 16 can be channelled to the third system 17. The electrical surge can be in the form of an excessive high electrical current or an excessive high voltage.
[56] The third system auxiliary power supply terminal 44 and the third system main power supply terminal 41 provide electrical connections for supplying electrical power supply to electrical circuits of the third system 17. A electrical power supply that is required by the third system main power supply terminal 41 is different from an electrical power supply that is required the third system auxiliary power supply terminal 44. The difference is in terms of voltage or electrical current rating. Because of the difference, the third system auxiliary power supply terminal 44 and the third system main power supply terminal 41 cannot be easily combined to form a single terminal.
[57] An electrical connection point for supplying electrical power supply to the electrical circuits of the first system 15 is provided by the first system incoming power supply terminal 35. Likewise, the second system incoming power supply terminal 36 provides an electrical connection point for supplying electrical power supply to the electrical circuits of the second system 16. The incoming power supply terminal 37 provides an electrical connection point for supplying electrical power supply to the electrical circuits of the other systems 18.
[58] The first system incoming ground terminal 24 provides an electrical ground connection point for electrical circuits that are within the first system 15. Similarly, the second system incoming ground terminal 25 and the other systems incoming ground terminal 26 provide an electrical ground connection points for electrical circuits that are within the second system 16 and the other systems 18 respectively. The third system main ground terminal 29 and the third system auxiliary ground terminal 33 provide an electrical ground connection points for electrical circuits within the third system 17. [59] The switch 13 and switch 14 are intended to make or to break electrical connection between the battery 11 and the plurality of the systems 12.
[60] Figs. 2 to 8 show several embodiments of protection device against load dumps. Figs.
1 to 8 have similar parts that are denoted with the same part reference number, the same part reference number with a single prime symbol, or the same part reference number with a double prime symbol. The description of the similar parts is thus included by reference.
[61] Figs. 2 to 5 depict several embodiments of the third system 17 of Fig. 1 that is connected to the first system 15 of Fig. 1 and to the second system 16 of Fig. 1.
[62] Fig. 2 illustrates a first electrical interface protection circuit 45 of the third system 17.
The first electrical interface protection circuit 45 has a main protection circuit 46 and an auxiliary protection circuit 47. The main protection circuit 46 is connected to a main interface 51 of the third system 17 whilst the auxiliary protection circuit 47 is connected to an auxiliary interface 53 of the third system 17.
[63] The main protection circuit 46 includes an inductor Ll, a capacitor Cl, and a clamping diode Dl. A first end of the inductor Ll is connected to the third system main power supply terminal 41 whilst a second end of the inductor Ll is connected to a first end of the capacitor Cl thereby forming a node 48. A second end of the capacitor Cl is connected to the third system main ground terminal 29. A cathode of the clamping diode Dl is connected to the node 48 whilst an anode of the clamping diode Dl is connected to the third system main ground terminal 29. The node 48 is connected to the main interface 51 of the third system 17. The clamping diode Dl is also called a voltage clamping diode.
[64] As shown in Fig. 2, the auxiliary protection circuit 47 comprises a capacitor C2 and a clamping diode D2. A first end of the capacitor C2 is connected to the third system auxiliary power supply terminal 44 whilst a second end of the capacitor C2 is connected to the third system auxiliary ground terminal 33. A cathode of the clamping diode D2 is connected to the third system auxiliary power supply terminal 44 whereas an anode of the clamping diode D2 is connected to the third system auxiliary ground terminal 33. The third system auxiliary power supply terminal 44 is also connected to the auxiliary interface 53. The clamping diode D2 is also called a voltage clamping diode.
[65] Functionally, the main protection circuit 46 and the auxiliary protection circuit 47 protect the main interface 51 and the auxiliary interface 53 against load dumps.
[66] The main protection circuit 46 receives a mainstream power supply 57 from the first system 15 whereas the auxiliary protection circuit 47 receives a non-mainstream power supply 58 from the second system 16. The mainstream power supply 57 provides power for main electrical circuits of the third system 17 and it has a maximum current rating of 10 A (ampere). Similarly, the non-mainstream power supply 58 provides power supply for special electrical circuits of the third system 17 and it has a maximum electrical current rating of 5 A.
[67] Because the maximum electrical current rating of the mainstream power supply 57 is different from the maximum electrical current rating of the non-mainstream power supply 58, it is difficult to combine the third system main power supply terminal 41 and the third system auxiliary power supply terminal 44 to form a single power terminal.
[68] The clamping diode Dl with the clamping diode D2 protects the main interface 51 and the auxiliary interface 53 against hardware damage of a load dump. The load dump has an energy surge that can be observed as an excessive high voltage or an excessive high electrical current.
[69] A load dump that is present in the mainstream power supply 57 would act to increase a voltage of the cathode of the clamping diode Dl. The clamping diode Dl limits the cathode voltage from exceeding a maximum value of typical 18.5 or 26.5 volts by channelling an electrical current of the mainstream power supply 57 from its cathode to its anode. The maximum value is also called a breakdown voltage. No electrical current effectively flows from the cathode of the clamping diode Dl to its anode, in normal situations. A cathode voltage of the clamping diode Dl is also greater than an anode voltage of the clamping diode Dl by less than the breakdown voltage.
[70] The size of the clamping diode D 1 is sufficiently large to handle a breakdown electrical current, which can be large. The energy surge of the load dump is diverted into the anode of the clamping diode Dl and away from the main interface 51. In this way, the main interface 51 is protected against hardware damage of the load dump into the third system 17.
[71] The clamping diode D2 in a similar manner protects the auxiliary interface 52 against a load dump that is present in the non-mainstream power supply 58.
[72] The inductor Ll with the capacitor Cl is intended for filtering of the mainstream power supply 58. The capacitor C2 is used for electrical noise rejection and for ESD (electrostatic discharge) protection.
[73] This embodiment advantageously provides protection for the third system 17 against load dumps.
[74] Fig. 3 illustrates a second electrical interface protection circuit 49. The second electrical interface protection circuit 49 includes the main protection circuit 46 of Fig. 2 and an auxiliary protection circuit 50.
[75] The auxiliary protection circuit 50 comprises a capacitor C2' and a high-side driver
52. A first end of the capacitor C2' is connected to the third system auxiliary power supply terminal 44 whereas a second end of the capacitor C2' is connected to the third system auxiliary ground terminal 33. A first end of the high-side driver 52 is connected to the third system auxiliary power supply terminal 44 whilst a second end of the high- side driver 52 is connected to the auxiliary interface 53 of the third system 17.
[76] The high-side driver 52 includes an integrated load dump protector, which has active switches that turn off when a load dump occurs. The active switches can be in the form of clamping diodes or of zener diodes. The integrated load dump protector is not shown in the figure.
[77] Functionally, the high-side driver 52 provides an electrical power supply for a load.
The integrated load dump protector protects the auxiliary interface 53 against a load dump by isolating the auxiliary interface 53 from the load dump via turning off the active switches.
[78] The zener diode is also called an avalanche breakdown diode. The zener diode permits an electrical current to flow in a forward direction when voltages across its terminal are below a certain breakdown voltage and an electrical current to flow in the reverse direction if the voltage across its terminal is larger than the certain breakdown voltage.
[79] Fig. 4 depicts a third electrical interface protection circuit 54. The third electrical interface protection circuit 54 includes the main protection circuit 46 of Fig. 2 or 3 as well as an auxiliary protection circuit 55. The auxiliary protection circuit 55 is connected to an auxiliary interface 53 of the third system 17.
[80] The auxiliary protection circuit 55 includes a capacitor C2", a thermistor Nl, and a voltage follower diode D3. A first end of the capacitor C2" is connected to the third system auxiliary power supply terminal 44 whereas a second end of the capacitor C2" is connected to the third system auxiliary ground terminal 33 and to an electrical ground 62 . A first end of the thermistor Nl is connected to the third system auxiliary power supply terminal 44 . A second end of the thermistor Nl is connected to an anode of the voltage follower diode D3 thereby forming a node 56. The node 56 is connected to the auxiliary interface 53. The cathode of the voltage follower diode D3 is connected to the cathode of the clamping diode Dl of the main protection circuit 46. The anode of the clamping diode Dl is connected to an electrical ground 63.
[81] In a functional sense, the auxiliary protection circuit 55 transfers a power of a non mainstream power supply 58 from the second system 16 to the auxiliary interface 53 and it protects the auxiliary interface 53 from load dump. Likewise, the main protection circuit 46 transfers a power of a mainstream power supply 57 from the first system 15 to the main interface 51 and it protects the main interface 51 against a load dump.
[82] The thermistor Nl and the voltage follower diode D3 are intended to replace the large clamping diode D2 of Fig. 2 or the high-side driver 52 of Fig. 3. [83] The thermistor Nl acts as an electrical current limiter and it prevents an excessive high electrical current from flowing through it. A load dump can generate excessive high electrical current. This action protects the voltage follower diode D3 against an over-current. The over-current is a condition of an electrical circuit wherein an electrical current in an electrical circuit exceeds a rated electrical current capacity of the electrical circuit or of an equipment that is connected to the electrical circuit.
[84] A maximum limit of the thermistor Nl is large enough such that it does not limit an input electric current to the auxiliary interface 53 during normal operations. The input electrical current of the auxiliary interface 53 flows through the thermistor Nl.
[85] A resistance of the thermistor Nl varies with the temperature of the thermistor Nl.
Moreover, the thermistor Nl, as provided here, is of a PTC (positive temperature coefficient) type, wherein a resistance of the thermistor Nl increases with higher thermistor temperature.
[86] During normal operations, a thermistor current flows through the thermistor Nl. The value of the thermistor current is less than maximum current rating of the thermistor Nl. The thermistor current generates heat that is dissipated by the thermistor Nl. During a load dump, a high electrical current flow through the thermistor Nl and heat that is generated by the thermistor Nl is not fully dissipated by the thermistor Nl. This causes the temperature of the thermistor Nl to increase significantly and correspondingly the resistance of the thermistor Nl to increase significantly. This in turn causes the thermistor current to be reduced significantly.
[87] The voltage follower diode D3 in co-operation with the clamping diode Dl acts to clamp the voltage of node 56 to a certain maximum value. The voltage follower diode D3 also prevents back flow of voltage and electrical current that is greater than parasitic to a specific interface during normal operations.
[88] A package size of the voltage follower diode D3 needs not be large. Forward electrical current of the voltage follower diode D3 is not large as the forward current of the clamping diode as it is limited by the current limiting function of the thermistor Nl. Thus, the package size of the voltage follower diode D3 does not need be large to support a large current. As the size of the voltage follower diode D3 is small, its cost is also less. Moreover, the voltage follower D3 is able to withstand a high reverse voltage. The reverse voltage occurs when a voltage of the cathode of the voltage follower D3 that is greater than a voltage of the anode of the voltage follower D3. The high reverse voltage does not cause an electrical current to flow from the cathode of the voltage follower D3 to the anode of the voltage follower D3.
[89] The electrical ground 62 and the electrical ground 63 act to sink electrical current in a manner that its electrical potential does not change.
[90] During normal operations, an input voltage at the third system auxiliary power supply terminal 44 is lower than a mainstream voltage of the third system main power supply terminal 41 due to voltage drop across the voltage follower diode D3. The voltage at the node 56, which is connected to the auxiliary interface 53, is almost the same as the input voltage. The thermistor resistance is low and it does not significantly increase an input impedance of the auxiliary interface 53.
[91] When a load dump is present in the mainstream power supply 57, an electrical current of the load dump is channelled through the terminals of the clamping diode Dl such that a high voltage of the load dump is prevented from exceeding a clamping voltage Vc, which represents a maximum voltage of the clamping diode Dl, in a way that is shown in the description of Fig. 2.
[92] Moreover, the voltage follower diode D3 isolates the auxiliary interface 53 from the high voltage of the load dump. The voltage follower diode D3 is able to withstand the high voltage that is present at its cathode and it does not allow the high voltage to cause an electrical current to flow from its cathode to its anode. In this manner, the auxiliary interface 53 is isolated from the load dump and is protected from hardware damage.
[93] When a load dump occurs at the non-mainstream power supply 58, a voltage of the load dump is also observed at the anode of the voltage follower diode D3, and at the cathode of the voltage follower D3. A slightly reduced voltage by about 0.7 V is also observed at the cathode of the clamping diode Dl. As the load dump voltage starts to increase, the clamping diode Dl acts to prevent the voltage of the load dump at its cathode from exceeding the clamping voltage Vc.
[94] The clamping diode Dl channels an electrical current of the load dump such that its cathode voltage does not exceed the clamping voltage Vc. The electrical current is channelled from the anode of the voltage follower diode D3 to cathode of the voltage follower diode D3, to the cathode of the clamping diode Dl, to the anode of the clamping diode Dl, and to the electrical ground 63. Effectively, a short-circuit from the anode of the voltage follower diode D3 to the electrical ground 63 is thereby created. In this manner, an energy surge of the load dump is channelled into the electrical ground 63 and away from the auxiliary interface 53. The auxiliary protection circuit 55 is thus protected against the load dump.
[95] In an electrical sense, the channelling causes a thermistor current of the thermistor
Nl to flow to the voltage follower diode D3 and not to the auxiliary interface 53. Hence, the thermistor Nl is, in this electrical sense, in series with the voltage follower D3.
[96] In an initial stage of the load dump, the amount of thermistor current increases and it does not exceed a maximum current rating of the thermistor Nl. The voltage of node 56, which represent an input voltage of the auxiliary interface 53, is limited to a sum of clamping voltage Vc of the clamping diode Dl and of voltage follower diode voltage V_d3, wherein the follower diode voltage V_d3 represents a voltage drop across the voltage follower diode D3.
[97] In the later stage of the load dump, the thermistor current reaches the maximum current rating of the thermistor Nl. At this stage, the heat generated by the thermistor current is not fully dissipated by the thermistor Nl. This causes the thermistor temperature to increase significantly. Correspondingly, the thermistor resistance also increases significantly. The increased thermistor resistance acts to limit the flow of the thermistor current. Later thermistor resistance is increased significantly and the flow of the thermistor current is also reduced significantly.
[98] The reduction of the thermistor current allows the thermistor Nl to dissipate heat and thereby bringing a corresponding fall of the thermistor temperature. The thermistor temperature afterward reduces to a level where the thermistor resistance is low enough for the thermistor current to flow again.
[99] During the cooling, if the load dump ceases operating, the thermistor resistance and the rest of the electrical circuit would later resume normal operation. The sequence of events described above repeats again, if the load dump is still active after the cooling.
[100] Hence, the input voltage of the auxiliary interface 53 is clamped to a sum of the clamping voltage Vc and of a voltage across the voltage follower D3, during the normal operation.
[101] The auxiliary protection circuit 55 can also be duplicated for other interfaces of the third system 17. The auxiliary protection circuit 55 can also be adapted to provide different current limits for different interfaces. The different current limits can be implemented using different thermistor Nl that has different current limit rating and using corresponding different voltage follower diode D3. It is believed that this adaption is easier than selecting different types of high- side driver.
[102] The embodiment provides a low cost electrical circuit with protection level that is similar to other types of protection circuit. The embodiment advantageously avoids the use of large components, such as clamping diodes or high-side drivers. The embodiment allows voltage-clamping action to be performed by one large component, instead of several large components. The maximum current of the auxiliary interface 53 is limited by the thermistor Nl. The size of the clamping diode D3 need not be large to handle energy surges.
[103] Beside the advantages stated above, the auxiliary protection circuit 55 has a reduced size. A PCB (printed circuit board) using the auxiliary protection circuit 55 would have a reduced PCB real estate. The size of the thermistor is relatively small. In addition to the current limiting feature of the thermistor Nl, the voltage follower diode D3, which routes a voltage at its anode to its cathode and to the clamping diode Dl, can relatively small as compared to a clamping diode. It is believed that a clamping diode costs about 10 times more than a cost of the auxiliary protection circuit 55. This thereby results in a reduction of a BOM (bill of material) of the overall system.
[104] In a special embodiment of Fig. 4, a current limiter, such as a thermistor, is placed in series with the voltage follower diode D3 and is placed between the node 56 and the node 48. The current limiter acts to prevent excessive electrical current from reaching the voltage follower diode D3. The current limiter can be provided in place of the thermistor Nl or in addition to the thermistor Nl.
[105] Fig. 5 shows the third electrical interface protection circuit 54 of Fig. 4 with a resistor divider 60. The resistor divider 60 provides a diagnostic capability for the auxiliary protection circuit 55, which is shown in Fig. 4 description.
[106] The resistor divider 60 has a first resistor Rl and a second resistor R2. A first end of the first resistor Rl is connected to an electrical ground 80 whereas a second end of the first resistor Rl is connected to a first end of the second resistor R2 thereby forming a node 61. The node 61 is connected to an analogue to digital conversion (ADC) port 79 of a main processor 78. The second end of the second resistor R2 is connected to the node 56 that is shown in Fig. 4 description.
[107] The resistor divider 60 provides diagnostic capability to detect occurrence of a load dump at the auxiliary interface 53. The resistive divider 60 provides a stepped down voltage or a reduced voltage of the node 56. The reduced voltage can be used to detect a battery short or a ground short at the auxiliary interface 53 during normal operations.
[108] The main processor 78 uses the ADC port 79 to obtain a voltage reading of the node 61.
[109] The voltage reading provides an indication as to whether a voltage-clamping step or a current- limiting step of a load dump has occurred. The third system 17 can then respond with appropriate actions to the indication. When the current-limiting step occurs, the voltage reading at the main processor 78 will be a zero. If the voltage- clamping step occurs, the voltage reading would be scaled down a sum of a clamping voltage Vc and a follower diode voltage V_d3.
[110] In normal operations, it can also provide detection of a short-to-battery or a short- to-ground of interface pins or of cable harnesses that are connected to the auxiliary interface 53 of the third system 17.
[I l l] The resistor divider 60 provides a low cost diagnostic capability. It is believed that the diagnostic capability costs tens times less that a similar diagnostic capability that is provided by a high-side driver.
[112] Fig. 6 shows an embodiment of the third electrical interface protection circuit of Fig. 5. The embodiment illustrates an application of the third electrical interface protection circuit in a vehicle. [113] Fig. 6 depicts an vehicle 69 with the third system 17 that is provided here as a controller, with the second system 16 that is provided here as a temperature sensor, and with the first system 15 that is provided here as a steering wheel motor.
[114] The vehicle 69 comprises a steering wheel system 70. The steering wheel system 70 includes a steering wheel 71 that is connected to a shaft 72. The shaft 72 is connected to a steering mechanism of a wheel 74. A voltage reading 76 of the resistor divider 60 of the controller 17 is transmitted a digital conversion (ADC) port 79 of the main processor 78.
[115] The controller 17 receives a temperature electrical signal 65 from the temperature sensor 16. The controller 17 also receives a position signal 67 from the steering wheel motor 15.
[116] The vehicle 69 provides a mode of transportation. The vehicle 69 can be in the form of an automobile. The temperature sensor 16 generates temperature readings of a combustion engine of the vehicle 69 and it sends the temperature readings to the controller 17 for managing the combustion engine. The steering wheel motor 15 records the steering wheel positions and it sends the steering wheel positions to the controller 17 also for managing the combustion engine.
[117] Fig. 7 shows a fourth electrical interface protection circuit 85 of a fourth system 86. The fourth system 86 is connected to the third system 17 of Fig. 4.
[118] The fourth electrical interface protection circuit 85 includes a second auxiliary protection circuit 88 and a second auxiliary interface 89 that is connected to the second auxiliary protection circuit 88.
[119] The second auxiliary protection circuit 88 comprises a second thermistor Nl' and a second voltage follower diode D3'. One end of the second thermistor Nl' is connected to an outgoing power supply terminal 92 of the auxiliary interface 53 of Fig. 4. Another end of the second thermistor Nl' is connected to an anode of the second voltage follower diode D3' thereby forming node 92 and to the second auxiliary interface 89. A cathode of the second voltage follower diode D3' is connected to the node 48 of Fig. 4.
[120] The second auxiliary protection circuit 88 receives a second non-mainstream power supply 95 from the third system 17. The second non-mainstream power supply 95 provides a power supply for electrical circuits of the fourth system 86 via the thermistor Nl '.
[121] Similar to the auxiliary protection circuit 55, the second auxiliary protection circuit 88 channels a load dump at its terminal to the clamping diode Dl of the main protection circuit 46 of Fig. 4. An operation of the second auxiliary interface 89 may generate the load dump. The load dump is channelled from the anode of the second voltage follower diode D3' to the cathode of the second voltage follower diode D3', to the anode of the clamping diode Dl, to the anode of the clamping diode Dl, and to the electrical ground 63 of Fig. 4. The second thermistor Nl' limits an electrical current flowing through its terminal during the load dump.
[122] Fig. 8 depicts an embodiment of Fig. 7 to provide a more concrete example of the Fig. 7. Fig. 8 shows an ignition switch 100 of an automotive.
[123] The ignition switch 100 is connected to the car battery 11 of Fig. 1 by a wire 112. A wire 110 connects the ignition switch 100 to a fan control 102 that is provided by the third system 17. The fan control 102 is connected to a fan 104 that is provided by the fourth system 86. A wire 111 connects the ignition switch 100 to an air-conditioning compressor 103 that is provided by the third system 17. The voltage follower diode D3 connects a load-dump protection circuit of the fan control 102 to a load-dump protection circuit of the air-conditioning compressor 103. Similarly, the voltage follower diode D3' connects a load-dump protection circuit of the fan 104 to the load- dump protection circuit of the air-conditioning compressor 103.
[124] The ignition switch 100 is intended for selecting a run state, a standby state, and an off state of the automobile.
[125] The voltage follower diode D3 acts to channel a load-dump at the load-dump protection circuit of the fan control 102 to the load-dump protection circuit of the air- conditioning compressor 103. Likewise, t he voltage follower diode D3' acts to channel a load-dump at the load-dump protection circuit of the fan 104 to the load-dump protection circuit of the air-conditioning compressor 103.
[126] In the standby state, the fan control 102 receives the non-mainstream power supply 58 from the car battery 11 via the ignition switch 100. An engine of the automotive is not operating or running whilst the car battery 11 does not receive power from an alternator of the automotive. The fan control 102 provides the non-mainstream power supply 95 to the fan 104, which may be running depending on a setting of the fan control 102.
[127] The fan control 102 receives the non-mainstream power supply 58 from the car battery 11, in the run state. The engine is also running for the alternator to charge up the car battery 11. The fan control 102 also provides the non-mainstream power supply 95 to the fan 104 whilst the air-conditioning compressor 103 receives the mainstream power supply 57.
[128] In contrast, the fan 104, the fan control 102, and the air-conditioning compressor 103 do not receive the non-mainstream power supply 58 and the mainstream power supply 57, in the off state.
[129] The fan control 102 and the air-conditioning compressor 103 may receive load dumps via the wire 110 and the wire 111 respectively. The fan 104 may also generate a load dump via due to its high inductance. The fan control 102, the air-conditioning compressor 103, and the fan 104 have load dump protection circuits for protecting against the load dumps.
[130] The protection circuit of the fan control 102 and the protection circuit of the fan 104 channel surge energy of their respectively load dumps to the protection circuit of the air-conditioning compressor 103 in a manner described earlier.
[131] The above embodiments are configured such that an Ilimit (maximum current rating of the thermistor Nl) is greater than an Imax (maximum current rating of the auxiliary interface 53). An Iforward (maximum forward current of the diode D3) is greater than the Ilimit (maximum current rating of the thermistor Nl). A Vd3 (voltage drop of voltage follower diode D3) is greater than a VIl (voltage drop across inductor Ll). The resistor divider 60 of Fig. 5 detects the presence of a load dump using voltages and it is does not exceed a maximum input voltage of the main processor.
[132] In short words, the above embodiments provide electrical protection circuits that protect against a load dump of multiple interfaces of an automobile system by channeling the load dump into a single interface. The electrical protection circuits protect the multiple interfaces against large electrical currents of the load dump by disconnecting the multiple interfaces from the large electrical current and against high voltages of the load dump by clamping the high voltages.
[133] The electrical protection circuit is implemented at low cost by avoiding duplication of large clamping diodes and by providing an alternative to integrated high- side driver components.
[134] Reference numbers
[135] 10 automotive electrical system
[136] 11 battery
[137] 12 a plurality of systems
[138] 13 switch
[139] 14 switch
[140] 15 first system
[141] 16 second system
[142] 17 third system
[143] 18 other systems
[ 144] 20 first input interface
[145] 21 positive terminal
[146] 22 negative terminal
[147] 24 first system incoming ground terminal
[148] 25 second system incoming ground terminal
[149] 26 other systems incoming ground terminal
[150] 28 first system outgoing ground terminal [151] 29 third system main ground terminal
[152] 32 second system outgoing ground terminal
[153] 33 third system auxiliary ground terminal
[154] 35 first system incoming power supply terminal
[155] 36 second system incoming power supply terminal
[156] 37 other systems incoming power supply terminal
[157] 40 first system outgoing power supply terminal
[158] 41 third system main power supply terminal
[159] 43 second system outgoing power supply terminal
[160] 44 third system auxiliary power supply terminal
[161] 45 first electrical interface protection circuit
[162] 46 main protection circuit
[163] 47 auxiliary protection circuit
[164] 48 node
[165] 49 second electrical interface protection circuit
[166] 50 auxiliary protection circuit
[167] 51 main interface
[168] 52 high-side driver
[169] 53 auxiliary interface
[170] 54 third electrical interface protection circuit
[171] 55 auxiliary protection circuit
[172] 56 node
[173] 57 mainstream power supply
[174] 58 non- mainstream power supply
[175] 60 resistor divider
[176] 61 node
[177] 62 electrical ground
[178] 63 electrical ground
[179] 65 temperature electrical signal
[180] 67 position signal
[181] 69 vehicle
[182] 70 steering wheel system
[183] 71 steering wheel
[184] 72 shaft
[185] 74 steering mechanism of a wheel
[186] 76 voltage reading
[187] 78 main processor
[188] 79 digital conversion (ADC) port [189] 80 electrical ground
[190] 85 fourth electrical interface protection circuit
[191] 86 fourth system
[192] 88 second auxiliary protection circuit
[193] 89 second auxiliary interface
[194] 92 outgoing power supply terminal
[195] 93 node
[196] 95 non-mainstream power supply
[197] 100 ignition switch
[198] 102 fan control
[199] 103 air-conditioning compressor
[200] 104 fan
[201] 110 wire
[202] 111 wire
[203] 112 wire
[204] Ll inductor
[205] Cl capacitor
[206] Dl clamping diode
[207] C2 capacitor
[208] C2' capacitor
[209] C2" capacitor
[210] D2 clamping diode
[211] D3 voltage follower diode
[212] D3' voltage follower diode
[213] Nl thermistor
[214] Nl ' thermistor Nl '
[215] Vc clamping voltage
[216] V_d3 follower diode voltage

Claims

Claims
[1] An automotive electrical device (17) comprising
- a first interface (51) with a first load dump protection device (46), and
- a second interface (53) with a second load dump protection device (55), wherein the second load dump protection device (55) comprises a voltage follower (D3), a first end of the voltage follower (D3) being connected to the first load dump protection device (46), and a second end of the voltage follower (D3) being connected to the second interface (53).
[2] An automotive electrical device (17) according to claim 1, characterised in that the voltage follower (D3) channels a load dump at the second interface (53) to the first load dump protection device (46). [3] An automotive electrical device (17) according to claim 1 or 2, characterised in that the voltage follower comprises a diode (D3). [4] An automotive electrical device (17) according to claim 3, characterised in that an anode of the diode (D3) is connected with the second interface (53) and a cathode of the diode (D3) is connected with the first load dump protection device
(46). [5] An automotive electrical device (17) according to one of the aforementioned claims characterised in that the second load dump protection device (55) comprises an electrical current limiter (Nl). [6] An automotive electrical device (17) according to claim 5 characterised in that the electrical current limiter is provided in series with the voltage follower (D3). [7] An automotive electrical device (17) according to claim 5 or 6 characterised in that the electrical current limiter is provided in series with the second interface (53). [8] An automotive electrical device (17) according to claim 7 characterised in that the electrical current limiter is provided between a power supply to the second interface (53) and the second interface (53). [9] An automotive electrical device (17) according to one of the claims 5 to 8, characterised in that the electrical current limiter comprises a thermistor (Nl). [10] An automotive electrical device (17) according to one of aforementioned claims characterised in that the automotive electrical device (17) further comprises a voltage sensing device
(60). [11] An automotive electrical device (17) according to claim 10 characterised in that the voltage sensing device comprises a resistor divider (60). [12] An automotive electrical device (17) according to one of aforementioned claims characterised in that the first load dump protection device (46) comprises a voltage clamping diode
(Dl). [13] An automotive electrical device (17) according to one of claims 1 to 11 characterised in that the first load dump protection device (46), a high-side driver (52) with a load dump protector. [14] An automotive electrical device (17) according to one of the aforementioned claims characterised in that the automotive electrical device (17) comprises
- a third interface (89) with a third load dump protection device (85), wherein the third load dump protection device (85) comprises a further voltage follower (D31), a first end of the further voltage follower (D31) being connected to the first load dump protection device (46), and a second end of the further voltage follower (D31) being connected to the third interface (89). [15] An automotive electrical device (17) according to claim 14, characterised in that the further voltage follower (D31) channels a load dump at the third interface (89) to the first load dump protection device (46). [16] An automotive electrical device (17) according to claim 14 or 15, characterised in that the further voltage follower comprises a diode (D31). [17] An automotive electrical device (17) according to claim 16, characterised in that an anode of the diode (D31) is connected with the third interface (89) and a cathode of the diode (D31) is connected with the first load dump protection device (46). [18] An automotive electrical device (17) according to one of the claims 14 to 17, characterised in that an output (92) of the second interface (53) is connected to the third interface (89) [19] An automotive on-board electric power system comprising
- at least one electrical device (17) according to one of the aforementioned claims,
- a first power source device (15) with a first power supply terminal (40), the first power supply terminal (40) being connected with the first load dump protection device (46),
- a second power source device (16) with a second power supply terminal (43), the second supply terminal (43) being connected with the second load dump protection device (55).
[20] Vehicle with an on-board electric power system according to claim 19, wherein the first power source device (15) and the second power source device (16) are connected to a power supply unit. [21] Vehicle according to claim 20 characterised in that the vehicle further comprises a main processor (78) that is connected to a voltage sensing device (60) according to claim 10 or 11. [22] Method for providing power to an electrical automotive device (17) with a first interface (51) and with a second interface (53), the method comprising the following steps:
- monitoring the first interface (51) for a first load dump and protecting the first interface (51) by channeling the first load dump to a power sink (63),
- monitoring the second interface (53) for a second load dump and protecting the second interface (53) by channeling the second load dump to the power sink (63).
[23] Method according to claim 22, characterised in that the step of channeling the second load dump from the second interface (53) to the first interface (51) comprises the step of limiting an electrical current which is caused by the channeling of the second load dump. [24] Method according to claim 22 or 23, characterised in that there is provided a step of limiting an electrical current of the second interface
(53)
EP08789407.7A 2008-07-23 2008-07-23 Protection against load dump on multiple automobile interfaces Withdrawn EP2307225A4 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IB2008/052946 WO2010010423A1 (en) 2008-07-23 2008-07-23 Protection against load dump on multiple automobile interfaces

Publications (2)

Publication Number Publication Date
EP2307225A1 true EP2307225A1 (en) 2011-04-13
EP2307225A4 EP2307225A4 (en) 2017-11-22

Family

ID=41570061

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08789407.7A Withdrawn EP2307225A4 (en) 2008-07-23 2008-07-23 Protection against load dump on multiple automobile interfaces

Country Status (2)

Country Link
EP (1) EP2307225A4 (en)
WO (1) WO2010010423A1 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013079997A1 (en) * 2011-12-02 2013-06-06 Continental Automotive Gmbh Adaptable voltage level detection with resistive ladder

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU6661800A (en) * 1999-10-29 2001-05-03 Tekonsha Engineering Company Load dump protection circuit
CN100408382C (en) * 2003-11-26 2008-08-06 力特保险丝有限公司 Vehicle electrical protection device and system employing same
US20060087778A1 (en) * 2004-10-21 2006-04-27 Hau Marvin G Load dump protection circuit
JP5562246B2 (en) * 2007-10-30 2014-07-30 アギア システムズ インコーポレーテッド ESD protection circuit

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2010010423A1 *

Also Published As

Publication number Publication date
WO2010010423A1 (en) 2010-01-28
EP2307225A4 (en) 2017-11-22

Similar Documents

Publication Publication Date Title
CN109417292B (en) Power supply device
US6239515B1 (en) Circuit for the protection of electrical devices
US20070229050A1 (en) Power converter
US6639389B2 (en) Arrangement and method for protecting multiple voltage supply systems against voltage arc-over between different voltage planes and against pole reversal from the outside
CN113711453A (en) Circuit breaker
GB2233125A (en) Alternator voltage transient minimisation.
CN112092625A (en) Detection device, switching device, power supply system, detection method and method
EP1650845A2 (en) Load dump protection circuit
US5923210A (en) High side driver circuit with diagnostic output
US20230356596A1 (en) Vehicle Electrical System Having A High-Voltage Branch, A Low-Voltage Branch, And Low-Voltage-Side Insulation Fault Detection
EP0341460B1 (en) Driver protection circuit
US7492561B2 (en) Protective circuit
EP2307225A1 (en) Protection against load dump on multiple automobile interfaces
US20040051398A1 (en) Device for rapid short-circuit protection in a power semiconductor
US20240100956A1 (en) Control unit circuit for a motor vehicle, motor vehicle and operating mathod for the control unit circuit
KR101996614B1 (en) Circuit for protecting against counter electromotive force
US6650521B2 (en) Voltage division method for protection against load dump conditions
EP1635463B1 (en) Discrete circuit for driving field effect transistors
US7224561B2 (en) Protective circuit and method for operating said protective circuit, in particular for overvoltage protection for an electronic control system for a motor vehicle
KR101984974B1 (en) Circuit for protecting against counter electromotive force
CN113039693A (en) Separating device for an electrochemical energy storage system
EP4178057A1 (en) Electrical energy storage device with an internal electronic circuit and an intrinsically safe freewheeling element and protection circuit for such an electrical energy storage device
EP4287428A1 (en) Overvoltage protection circuit
JPH10136697A (en) Control equipment of generator for vehicle
AU2018211234B2 (en) An Alternator Surge Clipping Device

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20110223

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA MK RS

DAX Request for extension of the european patent (deleted)
RA4 Supplementary search report drawn up and despatched (corrected)

Effective date: 20171019

RIC1 Information provided on ipc code assigned before grant

Ipc: H02H 7/06 20060101ALI20171013BHEP

Ipc: B60L 11/18 20060101AFI20171013BHEP

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20180519