CN115117847A - High-side switch design and driving method thereof - Google Patents
High-side switch design and driving method thereof Download PDFInfo
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- CN115117847A CN115117847A CN202210790885.4A CN202210790885A CN115117847A CN 115117847 A CN115117847 A CN 115117847A CN 202210790885 A CN202210790885 A CN 202210790885A CN 115117847 A CN115117847 A CN 115117847A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
- H02H3/207—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage also responsive to under-voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/24—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to undervoltage or no-voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
- H02H7/222—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices for switches
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
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Abstract
The application relates to a high-side switch, which comprises an under-voltage detection unit, a low-voltage protection unit and a control unit, wherein the under-voltage detection unit is configured to compare a power supply signal of the high-side switch with a preset threshold value and output an under-voltage protection signal according to a comparison result; a power transistor, a first pole of which is coupled with a power supply and receives a power supply signal of the high-side switch, and a second pole of which is coupled with an external load; a control module coupled to a control electrode of the power transistor and including at least a pull-down unit and a pull-down enhancement unit; an overvoltage protection unit coupled between the power supply and ground and configured to start operating to bleed off voltage between the power supply and the ground when a voltage between the power supply and the ground is greater than an overvoltage threshold voltage; the application also discloses an electronic device comprising the high-side switch and a driving method for protecting the high-side switch.
Description
Technical Field
The present application relates to the field of electrical control, and in particular, to a high-side switch design and a method for driving a high-side switch.
Background
The high-side switch is a switching circuit which is commonly applied in production and manufacturing, can save cost, can realize economic and efficient high-current load control, and is widely applied to electronic equipment such as automobile control and industrial lighting.
When the load to be driven by the high-side switch includes an inductive load and a resistive load, the current still flows in the inductive load after the high-side switch is turned off. If the freewheeling current in the inductive load cannot be stopped for the desired period of time, the load, such as a relay, cannot be stopped for the desired period of time, possibly causing damage to external devices or system circuitry. In the prior art, the safety problem of the device caused by too long free-wheeling current leakage time is often ignored. Since the problem occurs more often in an abnormal operating state, such as a failure of equipment or a collision of a vehicle, if the relay is not turned off after the freewheeling current is discharged in a short time, serious consequences, such as a battery fire, may occur. Compensation in the external circuit may in turn affect the proper operation of the other circuits. Therefore, there is a need for a high-side switch circuit that effectively ensures the follow current in the inductive load to be quickly released while not causing functional damage to the high-side switch and the external device when the high-side switch is required to be quickly turned off due to abnormal operation.
Disclosure of Invention
Aiming at the technical problems in the prior art, the application provides a high-side switch, which comprises an under-voltage detection unit, a low-voltage protection unit and a control unit, wherein the under-voltage detection unit is configured to compare a power supply signal of the high-side switch with a preset threshold value and output an under-voltage protection signal according to a comparison result; a power transistor, a first pole of which is coupled with a power supply and receives a power supply signal of the high-side switch, and a second pole of which is coupled with an external load; the control module is coupled to the control electrode of the power transistor and at least comprises a pull-down unit and a pull-down enhancement unit and is configured to pull down the control electrode voltage of the power transistor by using the pull-down unit and/or the pull-down enhancement unit under the control of the under-voltage protection signal; an overvoltage protection unit coupled between the power source and ground, configured to start operating to bleed off voltage between the power source and the ground when a voltage between the power source and the ground is greater than an overvoltage threshold voltage.
In particular, the control module further includes a driving unit configured to receive a power signal and provide a driving voltage to the pull-down unit and the gate of the power transistor.
In particular, the pull-down unit comprises a first controlled current source, which is coupled between the control electrode and the second electrode of the power transistor and is controlled by the control module to pull down the control voltage of the power transistor; the pull-down enhancement unit comprises a second controlled current source, the second controlled current source is coupled between the control electrode and the second electrode of the power transistor, and the control module is used for controlling to pull down the control voltage of the power transistor.
In particular, the pull-down unit includes a third controlled current source coupled between the control electrode and the second electrode of the power transistor, and when the power signal is lower than the preset threshold, the under-voltage protection signal is active, the third controlled current source starts to operate, and the control electrode voltage of the power transistor is pulled down; the pull-down enhancement unit comprises a fourth controlled current source coupled between the control electrode and the second electrode of the power transistor, when the power signal is lower than the preset threshold value, the undervoltage protection signal is effective, the fourth controlled current source starts to work, and the control electrode voltage of the power transistor is pulled down.
In particular, the preset threshold includes a first sub-threshold and a second sub-threshold, and the second sub-threshold is smaller than the first sub-threshold; the pull-down unit comprises a fifth controlled current source coupled between the control electrode and the second electrode of the power transistor, when the power supply signal is lower than the first threshold value, the first under-voltage protection signal is effective, the fifth controlled current source starts to work, and the control electrode voltage of the power transistor is pulled down; the pull-down enhancement unit comprises a sixth controlled current source coupled between the control electrode and the second electrode of the power transistor, when the power supply signal is lower than the second sub-threshold value, the second under-voltage protection signal is effective, the fifth controlled current source stops working, and the sixth controlled current source starts working; or when the power supply signal is lower than the second sub-threshold, the second under-voltage protection signal is valid, the fifth controlled current source keeps the working state, and the sixth controlled current source starts to work.
In particular, the current of the sixth controlled current source is larger than the current of the fifth controlled current source.
In particular, the under-voltage detection unit includes a first comparator, a negative input terminal of the first comparator is configured to receive the power signal, a positive input terminal of the first comparator is configured to receive a first reference signal having the predetermined threshold, and an output terminal of the first comparator is coupled to the control module.
In particular, the brown-out detection unit includes a second comparator and a third comparator, a negative input terminal of the second comparator is configured to receive a power signal, a positive input terminal of the second comparator is configured to receive a second reference signal having the first sub-threshold, and an output terminal of the second comparator is coupled to the control module; the negative input terminal of the third comparator is configured to receive a power signal, the positive input terminal of the third comparator is configured to receive a third reference signal having the second sub-threshold, and the output terminal of the third comparator is coupled to the control module.
In particular, the high-side switch further comprises a diode having an anode coupled to the second pole of the power transistor and a cathode coupled to the control pole of the power transistor.
The application also discloses an electronic device comprising the high-side switch.
The application also discloses a driving method for protecting the high-side switch, which comprises the steps of detecting whether the power supply voltage is lower than a preset threshold value, wherein the preset threshold value is higher than the turn-off voltage of the high-side switch; and when the power voltage is lower than the preset threshold value, starting the under-voltage protection, and starting the pull-down unit and/or the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch.
In particular, the preset threshold comprises a first sub-threshold and a second sub-threshold, the second sub-threshold being lower than the first sub-threshold but both higher than the turn-off voltage of the high-side switch; when the power supply voltage is lower than the first sub-threshold, starting a pull-down unit to pull down the control electrode voltage of a power transistor in a high-side switch; when the power supply voltage is lower than the second sub-threshold, closing the pull-down unit, and opening the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch; or when the power supply voltage is lower than the second sub-threshold, keeping the pull-down unit in an opening state, and opening the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch; wherein the pull-down enhancing unit has a pull-down capability higher than that of the pull-down unit.
By adopting the scheme of the application, the problems that the power transistor in the high-side switch cannot be turned off in time and the output of the high-side switch cannot become a negative value when the power supply is stopped at the outside so as to assist the inductive load current to be discharged can be effectively improved. The design and control of a specific protection structure are carried out on specific conditions, so that the influence of an abnormal working state on other modules of the whole circuit is reduced, the process and manufacturing cost for modifying the whole external circuit for protecting the high-side switch and partial circuits are reduced, and the protection method of the high-side switch is more generally applicable.
Drawings
Preferred embodiments of the present application will now be described in further detail with reference to the accompanying drawings, in which:
fig. 1A is a schematic circuit diagram of a conventional high-side switch;
FIG. 1B is a timing diagram of the operation of the high-side switching circuit shown in FIG. 1A;
FIG. 2A is a schematic diagram of a high-side switch according to one embodiment of the present application;
FIG. 2B is a schematic diagram of a circuit configuration of a high-side switch according to one embodiment of the present application;
FIG. 2C is a timing diagram illustrating the operation of the high side switch of one embodiment as shown in FIG. 2B;
FIG. 3A is a schematic diagram of a circuit configuration of a high-side switch according to another embodiment of the present application;
FIG. 3B is a timing diagram illustrating the operation of the high side switch of one embodiment as shown in FIG. 3A; and
fig. 4 is a circuit schematic of a high-side switch according to yet another embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
In the following detailed description, reference is made to the accompanying drawings that form a part hereof and in which is shown by way of illustration specific embodiments of the application. In the drawings, like numerals describe substantially similar components throughout the different views. Various specific embodiments of the present application are described in sufficient detail to enable those skilled in the art, having the benefit of this disclosure, to practice the subject application. It is to be understood that other embodiments may be utilized and structural, logical or electrical changes may be made to the embodiments of the present application.
A transistor may refer to a transistor of any structure, such as a Field Effect Transistor (FET) or a Bipolar Junction Transistor (BJT). When the transistor is a field effect transistor, the transistor can be hydrogenated amorphous silicon, metal oxide, low-temperature polysilicon, an organic transistor, or the like, depending on the channel material. An N-type transistor and a P-type transistor can be classified according to whether carriers are electrons or holes. The control electrode refers to a grid electrode of the field effect transistor, the first electrode can be a drain electrode or a source electrode of the field effect transistor, and the corresponding second electrode can be a source electrode or a drain electrode of the field effect transistor; when the transistor is a bipolar transistor, the control electrode of the transistor refers to a base electrode of the bipolar transistor, the first electrode may be a collector or an emitter of the bipolar transistor, and the corresponding second electrode may be an emitter or a collector of the bipolar transistor.
In the following detailed description of logic levels, the active level may be a high level or a low level depending on the circuit. In the following embodiments, for ease of understanding, the high level is described as the active level.
In the following detailed description, for the sake of understanding, a level at which the potential is zero is described as the ground potential.
In the following detailed description, positive voltages with opposite polarities can be generated across the same device according to the actual operation of the circuit, and in some cases, the positive polarity of the voltage is ground potential. For ease of understanding, the voltage across the device opposite to the positive and negative polarity of the device in its normal operating state will be described as a negative voltage.
A high-side switch is a load switch commonly used in electronic devices. Fig. 1A is a schematic circuit diagram of a conventional high-side switch. As shown in fig. 1A, the high-side switch 100 includes at least a gate controller 101, an ESD protection diode E1, and a power transistor M1. During normal operation of the device, the gate controller 101 receives the enable signal EN, and controls the gate voltage of the power transistor M1 under the driving of the power source Vin and the input voltage Vi, so as to control the on and off of the power transistor M1.
Some abnormal working states can occur in the use process of the electronic equipment, for example, the power line is loosened in the working process of the equipment, at the moment, the power Vin cannot continuously supply power to the high-side switch, and the capacitor Cin connected with the power in parallel in the external circuit discharges to continuously supply power to the high-side switch. Therefore, after the power Vin is turned off, the input voltage Vi of the high-side switch gradually decreases as the charge in the power capacitor Cin decreases. If Cin is not large enough, the potential of the output voltage Vo may be clamped by the ESD protection diode E1 in the conventional high-side switch 100, so that current still exists in the inductive load for a long time after Vin is turned off, and further, external devices may be damaged and even serious safety accidents such as battery fire may occur.
FIG. 1B is the high side switch shown in FIG. 1ATiming diagrams of circuit operation. As shown in FIG. 1B, when the power is turned on and the power Vin is at the active level, the circuit normally operates, the power transistor M1 operates in the linear region, and the gate-source voltage V of the power transistor M1 GS Is Vgs; when Vin is converted to an inactive level due to an abnormality of the power supply, the input voltage Vi of the high-side switch becomes a voltage V supplied by the charge stored in the power supply capacitor Cin CIN And begins to fall.
The limited charge stored in the power supply capacitor Cin may cause the input voltage Vi to drop at a relatively fast rate. When the input voltage Vi is reduced to the undervoltage protection threshold V UVLO The undervoltage protection function in the chip including the high-side switch is started, and the starting of the undervoltage protection function causes the grid-source voltage V of the power transistor M1 GS And begins to fall.
At this time, if the input voltage Vi is at the gate-source voltage V of the power transistor M1 GS Drops to the switch-off voltage V before dropping to its threshold voltage Vth OFF This may cause the gate-source voltages of other transistors in the gate controller 101 to be biased in a correct operation state, so that other circuits including the transistors may not operate normally. The switch-off voltage V here OFF Refers to a preset input voltage threshold value in the working process of the high-side switch, when the input voltage Vi received by the high-side switch is lower than the switch-off voltage V OFF In this case, the internal circuit of the high-side switch cannot be maintained to continue operating, and the corresponding gate controller 101 will stop operating and no longer control the power transistor M1.
The gate controller 101 cannot control the power transistor M1 continuously, so that the gate-source voltage V of the power transistor M1 is generated GS Cannot continue to fall, i.e. results in the gate-source voltage V of the power transistor M1 GS Remaining at a level above Vth, the power transistor M1 cannot be turned off. The output voltage Vo continues to drop until clamped by the ESD protection diode E1. Since the output voltage Vo may be lower than ground as it continues to drop, the output voltage is clamped to its threshold voltage-Vf, such as-0.7V, by the ESD protection diode E1. The output voltage Vo is not enough to discharge the current of the inductive load in a short time, resulting in thatThe inductive load current has longer discharge time, and the actual working requirement of the equipment is not met.
A commonly used solution to the above problem now includes, for example, coupling a voltage dividing diode or a voltage dividing resistor with a large resistance between the ground potential of the external circuit and the ESD protection diode E1 of the high-side switch, so that the ESD protection diode E1 is not turned on by the voltage division and Vo is not clamped to the threshold voltage of the ESD protection diode E1.
However, this method is improved on the outside of the high-side switch, i.e., the whole external circuit, and a voltage-dividing diode or a voltage-dividing resistor is often arranged in a ground network composed of a ground circuit of the whole device. Therefore, the ground potential of the output of the ground circuit prepared by the method may deviate, which may affect the logic level in the circuit, especially the low level, such as the judgment of the input level of the enable signal EN. In addition, because a voltage-dividing diode or a voltage-dividing resistor is added in the ground network, the integrity of the ground network can be damaged, and the heat dissipation of the chip through the ground network can be influenced. In this case, Vo is equal to Vi, so when Vo is negative, the input voltage Vi also appears as a negative voltage, and may cause damage to other devices connected in parallel to the power source Vin, such as a capacitor.
In order to solve the technical problem, the application provides a circuit design of a high-side switch, the change speed of voltage output to a load is controlled through specific conditions, the load current is effectively guaranteed to be rapidly released when the high-side switch is in an abnormal working state, the process cost is low, and the protection structure of the switch circuit is located inside the switch circuit, so that the influence on an external circuit and other devices in equipment is small.
According to an embodiment of the present application, the external load of the high-side switch may include an inductive load and a resistive load, and in practical applications, a current in the inductive load needs to be quickly drained when the high-side switch is turned off, so the present application provides the following embodiments.
Fig. 2A is a schematic diagram of a high-side switch according to an embodiment of the present application. According to an embodiment of the present application, the high-side switch 200 is a load switch applicable to an electronic device, and can receive an input signal Vi and an enable signal EN from the outside and output a signal Vo to the outside. The high-side switch 200 includes an input terminal Vin and a ground terminal Gc.
According to an embodiment of the present application, the ground terminal Gc may be directly coupled to a ground network in an external circuit, or may be coupled to the ground network in the external circuit by being coupled to other devices. The ground potential transmitted to the inside of the high-side switch 200 may be different in different connection manners, and the following description will take the example of direct coupling to generate the ground potential with a level of zero.
According to an embodiment of the present application, the enable signal EN is used to externally control the operating state of the high-side switch 200. When the enable signal EN is at an active level, the high-side switch 200 is turned on and maintains the operating state until the enable signal EN transitions to an inactive level. When the enable signal EN is at an inactive level, the high-side switch 200 stops operating. In the following description of the embodiments, the enable signal EN will remain active, keeping the high-side switch 200 in operation.
According to an embodiment of the present application, the input terminal Vin of the high-side switch 200 receives a power signal having a power voltage Vin, i.e. the input signal Vi, in a normal operating state. In an abnormal operating state, since the power signal abnormality may cause a voltage change, the high-side switch is powered by the voltage stored in the capacitor, and therefore the input signal Vi is used to refer to the power signal received by the high-side switch 200 after the external power source fails in the following description. The initial value of the power supply signal or the input signal Vi is the power supply voltage of the external power supply, and gradually decreases with time, depending on factors such as the size of a capacitor in the external power supply.
As shown in fig. 2A, the high-side switch 200 may include a power transistor 201 and a control module 202, wherein the control module 202 is configured to control a state of the power transistor 201 under driving of an input signal Vi. The power transistor 201 generates an output signal Vo to drive an external load. According to one embodiment of the present application, an external enable signal EN is received by the control module 202. According to an embodiment of the present application, the control module 202 may include a driving unit 221. The output of the driving unit 221 is coupled to the power transistor 201, so that the control module 202 controls the power transistor 201 to be turned on and off. According to an embodiment of the present application, the control module 202 may further include a pull-down unit 222, where the pull-down unit 222 is coupled to the output terminal of the driving unit 221, and pulls down the gate-source voltage of the power transistor 201 after receiving the signal output by the driving unit 221, so that the power transistor 201 is turned off.
According to an embodiment of the present application, the high-side switch 200 may further include an under-voltage detection unit 203, where the under-voltage detection unit 203 is coupled to the control module 202, and detects that the input signal Vi is abnormal, for example, lower than the under-voltage detection threshold voltage V REF In time, the under-voltage detection unit 203 sends an under-voltage protection signal SD to the control module 202, so that the high-side switch 200 stops working.
As shown in fig. 2A, the control module 202 may also include a pull-down enhancement unit 223. According to one embodiment, the pull-down enhancing unit 223 may not be disconnected from the pull-down unit 222 when there is no abnormality in the power supply. When the power supply is in an abnormal working state, the pull-down enhancing unit 223 and the pull-down unit 222 are coupled and work, the control module 202 can receive the under-voltage protection signal SD output by the under-voltage detecting unit 203, the pull-down enhancing unit 223 and the pull-down unit 222 accelerate the pull-down speed of the gate-source voltage of the power transistor 201 together, the ability of the pull-down unit 222 to pull down the power transistor 201 is enhanced, and it is ensured that Vi is lowered to V OFF The gate-source voltage of the power transistor 201 has previously reached its threshold voltage Vth, ensuring that the power transistor 201 can be turned off.
According to one embodiment of the present application, the pull-down capability of the pull-down enhancement unit 223 may be 5-20 times that of the pull-down unit 222. According to another embodiment of the present application, the pull-down capability of the pull-down enhancing unit 223 may be 10 times that of the pull-down unit 222. According to an embodiment of the present application, since the pull-down enhancing unit 223 can turn off the power transistor 201 faster, the capacitance of the power supply capacitor Cin can be smaller than 10uF, which is determined according to actual production requirements.
According to an embodiment of the present application, the high-side switch 200 may further include an overvoltage protection unit 204 coupled between the input terminal Vin and the ground terminal Gc. If the voltage between the input terminal Vin and the ground terminal Gc exceeds the overvoltage threshold voltage of the overvoltage protection unit 204 in the process, the overvoltage protection unit 204 starts to work, and the voltage between the input terminal Vin and the ground terminal Gc is discharged, so that the normal work of the equipment is ensured, and the circuit is not burnt out by the overhigh voltage.
According to other embodiments of the present application, the high-side switch 200 may further include other types of circuits, including but not limited to a current detection circuit, a fault reporting circuit, an over-temperature protection circuit, etc., and the specific structure is determined according to actual production needs.
According to an embodiment of the present application, during the normal operation of the high-side switch 200, the under-voltage detection unit 203 receives the input signal Vi and detects the voltage state. When the voltage signal transmitted to the control module 202 decreases to the undervoltage detection threshold voltage V REF In the meantime, the under-voltage detection unit 203 outputs the under-voltage protection signal SD to the control module 202, the pull-down unit 222 and the pull-down enhancement unit 223 start to operate after receiving the under-voltage protection signal SD, and the gate-source voltage of the power transistor 201 is lowered under the control of the pull-down unit 222 and the pull-down enhancement unit 223.
As the gate-source voltage of the power transistor 201 decreases, the output signal Vo of the high-side switch 200 gradually decreases. When the gate-source voltage of the power transistor 201 drops to its threshold voltage Vth, the power transistor enters a saturation region, a small current flows through the power transistor 201, the gate-source voltage does not change much, but the source-drain voltage changes greatly, so that the output signal Vo of the high-side switch still continuously drops to a negative voltage.
According to one embodiment, the output signal Vo is fixed at this voltage level by an external clamp circuit when it falls to a bleeding threshold voltage (e.g., -Vz). When the output signal Vo is clamped to the bleeding threshold voltage, a large potential difference is formed between the output signal Vo and the ground potential, and a bleeding path is formed between the source of the power transistor 201 and the ground network, so that the load current is quickly bled in a short time.
According to one embodiment of the application, the load may be coupled with an external voltage regulation protection circuit (not shown), which may include a zener diode (not shown), and the bleeding threshold voltage may be a threshold voltage Vz of the zener diode.
According to an embodiment of the present application, a power capacitor Cin connected in parallel with the power source may be provided outside the high-side switch 200, and when the power voltage Vin is abnormal, the power capacitor Cin provides the input signal Vi.
Fig. 2B is a circuit diagram of a high-side switch according to an embodiment of the present application. As shown in fig. 2B, the high-side switch 200 includes a power transistor 201, a gate of the power transistor 201 is coupled to the control module 202, a first pole is coupled to the input terminal Vin and receives the input signal Vi, and a second pole is coupled to the inductive load L. The load current on the inductive load L is io. The enable signal EN is received by the control module 202 and remains active at all times, keeping the high-side switch 200 in an active state.
According to an embodiment of the present application, the control module 202 may include a driving unit 221, wherein the driving unit 221 may include a charge pump (not shown) for raising the received input signal Vi to the driving voltage of the power transistor 201. According to one embodiment of the application, the driving voltage can be higher than Vi by about 5V, and is determined according to actual production requirements.
According to an embodiment of the present application, the control module 202 may further include a pull-down unit 222 coupled between the gate and the source of the power transistor 201, wherein the pull-down unit 222 may include a controlled current source i21 for pulling down the gate-source voltage of the power transistor 201 to turn off the power transistor 201. As shown in fig. 2B, one terminal of the controlled current source i21 is coupled to the gate of the power transistor 201, and the other terminal is coupled to the source of the power transistor 201.
As shown in fig. 2B, the control module 202 may further include a pull-down enhancing unit 223 connected in parallel with the pull-down unit 222, and the pull-down unit 223 may include a controlled current source i22 for increasing the turn-off speed of the power transistor 201. The controlled current source i22 is coupled to the gate of the power transistor 201 at one end and to the source of the power transistor 201 at the other end.
According to an embodiment of the present application, the design of the pull-down enhancement unit may be parameterized and configured according to actual production requirements in consideration of the influence of the circuit structure of the high-side switch 200 on EMI radiation. The current sources i22 and i21 in the pull-down enhancement unit 223 and the pull-down unit 222 should not be too large. According to an embodiment of the present application, the current provided by the current source i22 in the pull-down enhancement unit 223 may be 5-20 times the current provided by the current source i21 in the pull-down unit 222. According to an embodiment of the present application, the current provided by the current source i22 in the pull-down enhancing unit 223 may be 10 times that of the current source i21 in the pull-down unit 222.
According to other embodiments of the present application, the control module 202 may further include other circuits for coupling the gate of the power transistor 201 with the pull-down unit and/or the pull-down enhancement unit 223, which is not limited in this application and is determined according to actual production requirements.
According to an embodiment of the present application, the high-side switch 200 may further include an under-voltage detection unit 203, and the under-voltage detection unit 203 may include a comparator 231. The positive input of the comparator 231 receives the undervoltage detection threshold voltage V REF And the negative input receives the input signal Vi. When the input signal Vi is less than the undervoltage detection threshold voltage V REF Meanwhile, the comparator 231 outputs the under-voltage protection signal SD to the control module 202 to turn on the pull-down unit 222 and the pull-down enhancement unit 223. According to other embodiments of the present application, the brown-out detection threshold voltage V REF The value of (A) is determined according to actual production needs.
According to an embodiment of the present application, the overvoltage protection unit 204 may further include an ESD protection diode E21, wherein a cathode of the diode E21 receives the input signal Vi, an anode of the diode E21 is coupled to the ground terminal Gc, and the diode E21 breaks down when a voltage between the input signal Vi received by the high-side switch 200 and the ground terminal Gc is greater than an overvoltage threshold voltage.
According to an embodiment of the present application, the overvoltage threshold voltage of the overvoltage protection cell 204 may be a breakdown voltage of the ESD protection diode E21.
According to other embodiments of the present application, the overvoltage protection unit 204 may further include a zener diode circuit (not shown) composed of two diodes or other circuit structures for protecting the circuit from the overvoltage, and the specific circuit structure is not limited in this application and is determined according to actual production requirements.
As shown in fig. 2B, during the normal operation of the control module 202, the voltage output by the driving unit 221 is transmitted to the gate of the power transistor 201; the control module 202 receives the under-voltage protection signal SD from the under-voltage detection unit 203, and the under-voltage detection unit 203 detects that the input signal Vi is lower than the under-voltage detection threshold voltage V REF When the under-voltage protection signal SD is sent to the control module 202, the control module 202 turns on the pull-down unit 222 and the pull-down enhancement unit 223, the controlled current sources i21 and i22 start to work, and the gate-source voltage V of the power transistor 201 is pulled down together GS The power transistor 201 is turned off rapidly.
According to an embodiment of the present application, the control module 202 may enable the pull-down unit 222 and the pull-down enhancement unit 223 to start operating simultaneously after receiving the under-voltage protection signal SD, so as to pull down the gate-source voltage of the power transistor 201. Fig. 2C is a timing diagram of the operation of the high-side switch of one embodiment as shown in fig. 2B. As shown in fig. 2C, the pull-down enhancement unit 223 accelerates the falling speed of the gate-source voltage Vgs of the power transistor 201, eventually clamping Vo to the bleeding threshold voltage-Vz. In the following description of the operation of the high-side switch, the enable signal EN is maintained at an active level. Specifically, the method comprises the following working stages:
t 0 -t 1 : stage of normal operation
As shown in fig. 2C, in a normal working stage of the high-side switch 200, the power supply outputs a continuous and stable power supply voltage, the input terminal Vin receives the power supply voltage, the control module 202 provides a driving voltage for the power transistor 201, so that the power transistor 201 is turned on, and the output signal Vo is the same as the input signal Vi and is at a high level. The power transistor 201 is in the linear region with a gate-source voltage Vgs. The value of the load current io flowing through the inductive load L is at iL. The current iMOS flowing through the power transistor 201 and the current of the power supply capacitor Cin are both in accordance with the load current io.
According to an embodiment of the application, the voltage V stored by the supply capacitor Cin at this time CIN The same as the power source Vin.
t 1 -t 2 : beginning stage of abnormal work
As shown in fig. 2C, at the beginning of the abnormal operation, the power is turned off and the stable voltage is no longer supplied to the high-side switch 200. The high-side switch 200 is powered by an external power capacitor Cin, and the input terminal Vin receives a capacitor voltage V CIN The input signal Vi is composed of V CIN Gradually decreases. At this time, although the input signal Vi gradually decreases, it is still in the normal operating voltage range, and other devices in the high-side switch 200 operate normally. Since the power transistor 201 is still in the on state, the output signal Vo is the same as the input signal Vi and gradually decreases. The load current io starts to gradually decrease under the influence of the power source Vin. The values of iMOS and iC correspond to the load current io.
t 2 -t 3 : under-voltage protection stage
When the input signal Vi is reduced to the undervoltage detection threshold voltage V REF And continues to drop, the high-side switch 200 enters the under-voltage protection stage. The under-voltage detection unit 203 detects that the input signal Vi is lower than V REF And outputs the under-voltage protection signal SD to the control module 202. The control module 202 receives the under-voltage protection signal SD, turns on the pull-down enhancement unit 223 and the pull-down unit 222, and pulls down the gate-source voltage V of the power transistor 201 GS 。
According to an embodiment of the present application, after the pull-down unit 222 and the pull-down enhancing unit 223 are turned on, the power transistor 201 is discharged through a parasitic capacitance between the gate and the source.
t 3 -t 4 : transistor saturation phase
As shown in fig. 2C, under the action of the pull-down enhancing unit 223 and the pull-down unit 222, the gate-source voltage V of the power transistor 201 GS When the input signal Vi drops to the switch-off voltage V OFF Before the threshold voltage Vth is lowered, the transistor saturation phase is entered. When the power transistor 201 is in the saturation region, the gate-source voltage V GS No longer varies significantly, but the load current io can still freewheel through the power transistor 201, but due to the source-drain voltage V of the power transistor 201 DS The input signal Vi and the output signal Vo are not changed greatlyAre equal. The output signal Vo drops at a faster rate until it is clamped by an external clamping circuit, such as a zener diode Z1. At this stage, the current iC of the power supply capacitor Cin on the bleed path and the current iMOS of the power transistor 201 are kept the same as the load current io.
t 4 -t 5 : clamping protection phase
The output signal Vo continues to fall until it is clamped to the zener diode's threshold voltage-Vz by the external zener diode Z1. At this time, Vo drops to-Vz and remains unchanged, and the gate-source voltage V of the power transistor 201 GS Is pulled down to 0 and the power transistor 201 is in an off state. The drained load current io no longer flows through the power transistor 201 and the power supply capacitor Cin, and iMOS and iC jump to 0. The load current io is instead drained by the power transistor 201 through an external zener diode Z1. At this time, the value of the input signal Vi is larger than V OFF And remains unchanged. The current of the zener diode Z1 jumps from 0 to the value of the present load current io.
t 5 -t 6 : switch off phase
In the switch-off phase, as shown in fig. 2C, the load current io drops to 0 after being discharged through the discharge path formed by the external clamp circuit. At this point the high-side switch 200 is fully closed and the output signal Vo returns to 0, and no current flows through the inductive load L and the zener diode Z1.
According to an embodiment of the present application, in the case where the pull-down enhancing unit 223 and the pull-down unit 222 in the above-mentioned high-side switch 200 work together, the high-side switch 200 may turn off the power transistor 201 within 10 us. According to other embodiments of the present application, the turn-off time may be less than 1 us. The speed at which the output signal Vo falls may be greater than 2V/us by the pull-down unit 222 and the pull-down enhancing unit 223. In the case that the pull-down enhancing unit 223 operates, the size of the power supply capacitor Cin may also be reduced according to actual production requirements. According to an embodiment of the application, the supply capacitance Cin may be smaller than 10 uF.
According to the embodiment of the present application, the EMI radiation and corresponding noise interference generated by the pull-down enhancing unit 223 does not significantly affect the circuit itself and the actual device operation, and can be ignored, compared to the prior art high-side switch.
According to an embodiment of the present application, the high-side switch 200 may drain the current in the inductive load L within 5ms to turn off the corresponding relay, which significantly improves the safety of the system compared to the conventional high-side switch that generally requires at least 40ms to completely turn off the relay.
Fig. 3A is a schematic circuit diagram of a high-side switch according to another embodiment of the present application. As shown in fig. 3A, the high-side switch 300 may include a power transistor 301, a control module 302, and an overvoltage protection unit 304, which have the same or similar structure as the high-side switch 200 shown in fig. 2B. As with the high-side switch 200 shown in fig. 2B, the input terminal Vin receives a power supply voltage, and the ground terminal Gc is directly coupled to the ground network to generate a ground potential with a level of zero. In the following description of the embodiments, the enable signal EN will remain active, keeping the high-side switch 300 in operation.
According to an embodiment of the present application, the high-side switch 300 comprises a power transistor 301, a gate of the power transistor 301 being coupled to a control module 302, a first pole receiving the input signal Vi, and a second pole being coupled to the inductive load L. A load current io to be discharged after being turned off is generated on the inductive load L.
As shown in fig. 3A, the high-side switch 300 may further include an under-voltage detection unit 303, and the under-voltage detection unit 303 includes a comparator 331 and a comparator 332. The positive input terminal of the comparator 331 receives the first under-voltage detection threshold voltage V REF1 The negative input end receives an input signal Vi; the positive input terminal of the comparator 332 receives the second brown-out detection threshold voltage V REF2 And the negative input receives the input signal Vi.
According to one embodiment of the present application, the second brown-out detection threshold voltage V REF2 May be less than the first brown-out detection threshold voltage V REF1 Greater than the switch-off voltage V OFF The specific numerical value is determined according to actual production needs.
According to an embodiment of the present application, during normal operation of the high-side switch 300, the under-voltage detection unit 303 receives the input signal Vi and detects a voltage state.
According to one embodiment of the present application, the brown-out detection unit 303 receives the input signal Vi when the input signal Vi starts to gradually fall. When the input signal Vi is less than the first undervoltage detection threshold voltage V REF1 The comparator 331 outputs the first under-voltage protection signal SD1 to the control module 303. The control module 303 receives the SD1 to turn on the pull-down unit 322, the controlled current source i31 starts to work, and the gate-source voltage V of the pull-down power transistor 301 GS . At this point the pull-down enhancement unit 323 is not turned on. The input signal Vi continues to drop until it is less than the second brown-out detection threshold voltage V REF2 The comparator 332 outputs the second under-voltage protection signal SD2 to the control module 303. The control module 303 receives the SD2 to turn on the pull-down enhancing unit 323, and the controlled current source i32 also starts to operate, and the pull-down enhancing unit 323 and the pull-down unit 322 pull down the gate-source voltage V of the power transistor 301 GS 。
According to another embodiment of the present application, when the control module 303 receives the SD2, the pull-down unit 322 may be deactivated and the pull-down enhancement unit 223 may be activated. At this time, the controlled current source i31 stops working, the controlled current source i32 starts working, and the pull-down unit 322 changes the pull-down unit 323 to pull down the gate-source voltage V of the power transistor 301 GS 。
According to an embodiment of the present application, the pull-down capability of the pull-down enhancement unit 323 may be 5-20 times that of the pull-down unit 322. According to another embodiment of the present application, the pull-down capability of the pull-down enhancing unit 323 may be 10 times that of the pull-down unit 322. According to an embodiment of the present application, the current provided by the controlled current source i32 in the pull-down enhancement unit 323 may be 5-20 times the current provided by the controlled current source i31 in the pull-down unit 322. According to an embodiment of the present application, the current provided by the controlled current source i32 in the pull-down enhancement unit 323 may be 10 times that of the controlled current source i31 in the pull-down unit 322.
Fig. 3B is a timing diagram of the operation of the high-side switch of another embodiment as shown in fig. 3A. In the following description of the operation of the high-side switch, the enable signal EN is maintained at an active level. Specifically, the method comprises the following working stages:
t 0 -t 1 : stage of normal operation
As shown in fig. 3B, in the normal operation stage of the high-side switch 300, the power supply outputs a continuously stable power voltage, the input terminal Vin receives the power voltage, the control module 302 provides a driving voltage for the power transistor 301 to turn on the power transistor 301, and the output signal Vo is at a high level, which is the same as the input signal Vi. The power transistor 301 is in the linear region with a gate-source voltage Vgs. The value of the load current io flowing through the inductive load L is at iL. The current iMOS flowing through the power transistor 301 and the current of the power supply capacitor Cin both coincide with the load current io.
According to an embodiment of the application, the voltage V stored by the power supply capacitor Cin at this time CIN The same as the power source Vin.
t 1 -t 2 : beginning stage of abnormal work
As shown in fig. 3B, at the beginning of the abnormal operation, the power is turned off and the stable voltage is no longer supplied to the high-side switch 300. The high-side switch 300 is powered by an external power capacitor Cin, and the input terminal Vin receives a capacitor voltage V CIN The input signal Vi is composed of V CIN Gradually decreases. At this time, although the input signal Vi gradually decreases, it is still in the normal operating voltage range, and other devices in the high-side switch 300 operate normally. Since the power transistor 301 is still in the on state, the output signal Vo is the same as the input signal Vi and gradually decreases. The load current io starts to gradually decrease under the influence of the power source Vin. The values of iMOS and iC correspond to the load current io.
t 2 -t 3 : under-voltage protection stage
When the input signal Vi is reduced to the first undervoltage detection threshold voltage V REF1 And continues to drop, high side switch 300 enters the under-voltage protection phase. The under-voltage detection unit 303 detects that the input signal Vi is lower than V REF1 And outputs the under-voltage protection signal SD1 to the control module 302. The control module 302 receives the under-voltage protection signal SD1 to turn on the pull-down unit 322 to pull down the gate-source voltage V of the power transistor 301 GS 。
According to an embodiment of the present application, after the pull-down unit 322 is turned on, the power transistor 301 discharges through the parasitic capacitance between the gate and the source.
t 3 -t 4 : undervoltage protection enhancement stage
When the input signal Vi is lowered to the second undervoltage detection threshold voltage V REF2 And continues to drop, high-side switch 300 enters the undervoltage protection enhancement stage. The under-voltage detection unit 303 detects that the input signal Vi is lower than V REF2 And outputs the under-voltage protection signal SD2 to the control module 302. The control module 302 receives the under-voltage protection signal SD2 to turn on the pull-down enhancement unit 323.
At this time, the pull-down enhancing unit 323 pulls down the gate-source voltage V of the power transistor 301 together with the pull-down unit 322 GS . The power transistor 301 discharges through a parasitic capacitance between the gate and the source, a gate-source voltage V GS Will fall to the threshold voltage Vth with a shorter time at a faster rate, entering the off-phase.
According to another embodiment of the present application, after the control module 302 receives the under-voltage protection signal SD2, the pull-down unit 322 is disabled and the pull-down enhancement unit 323 is turned on. The gate-source voltage V of the power transistor 301 is pulled down by the pull-down enhancing unit 323 alone at this time GS . Since the pull-down capability of the pull-down enhancing unit 323 is greater than that of the pull-down unit 322, the gate-source voltage V of the power transistor 301 GS Will fall to the threshold voltage Vth with a shorter time at a faster rate, entering the transistor saturation phase.
t 4 -t 5 : transistor saturation phase
As shown in FIG. 3B, the gate-source voltage V of the power transistor 301 is under the action of the pull-down enhancing unit 323 and the pull-down unit 322 GS When the input signal Vi drops to the switch-off voltage V OFF Before dropping to the threshold voltage Vth, the transistor enters the saturation phase. When the power transistor 301 is in the saturation region, the gate-source voltage V GS No longer changes significantly, but the load current io can still freewheel through the power transistor 301, but due to the source-drain voltage V of the power transistor 301 DS The change is large, and the input signal Vi and the output signal Vo are not equal any more. Output signal Vo to be fasterUntil clamped by an external clamping circuit, such as a zener diode Z1. At this stage, the current iC of the power supply capacitor Cin on the bleed path and the current iMOS of the power transistor 301 are kept the same as the load current io.
t 5 -t 6 : clamping protection phase
The output signal Vo continues to fall until it is clamped to the zener diode's threshold voltage-Vz by the external zener diode Z1. At this time Vo drops to-Vz and remains unchanged, the gate-source voltage V of the power transistor 301 GS Is pulled down to 0 and the power transistor 301 is in an off state. The drained load current io no longer flows from the power transistor 301 and the supply capacitor Cin, and iMOS and iC jump to 0. The load current io is instead drained by the power transistor 301 through an external zener diode Z1. At this time, the value of the input signal Vi is larger than V OFF And remain unchanged. The current of the zener diode Z1 jumps from 0 to the value of the present load current io.
t 6 -t 7 : switch off phase
During the switch-off phase, as shown in fig. 3B, the load current io drops to 0 after being discharged through the bleed path formed by the external clamp circuit. At this point, the high-side switch 300 is completely closed, the output signal Vo returns to 0, and no current flows through the inductive load L and the zener diode Z1.
Fig. 4 is a circuit schematic of a high-side switch according to yet another embodiment of the present application. According to an embodiment of the present application, the source of the power transistor 401 may be grounded, and the control module 402 controls only the gate voltage of the power transistor 401.
As shown in FIG. 4, diode E42 has its anode coupled to the source of power transistor 401 and its cathode coupled to the gate of power transistor 401 at V G Ratio V S Much lower time pair V GS Clamping is performed to prevent the gate-source voltage V of the power transistor 401 GS The occurrence of an overvoltage causes the power transistor 401 to be damaged.
According to an embodiment of the present application, the gate of the power transistor 401 may be coupled with the pull-down unit 422 and/or the pull-down enhancement unit 423, and the gate voltage is pulled down by the pull-down unit 422 and/or the pull-down enhancement unit 423.
The application also discloses an electronic device comprising the high-side switch. The electronic device also includes other necessary modules and accessories to perform other complex functions. According to one embodiment of the application, the electronic equipment can rapidly turn off the high-side switch under the condition that the power supply is abnormal, such as the power line is loose, the current in the load circuit is discharged in a short time, and the safety is high.
The application also discloses a driving method for protecting the high-side switch, which comprises the following steps:
and detecting whether the power supply voltage is lower than a preset threshold value, wherein the preset threshold value is higher than the turn-off voltage of the high-side switch.
And when the power voltage is lower than the preset threshold value, starting the under-voltage protection, and starting the pull-down unit and/or the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch.
According to an embodiment of the application, the preset threshold comprises a first sub-threshold and a second sub-threshold, the second sub-threshold being lower than the first sub-threshold but both being higher than the turn-off voltage of the high side switch.
According to an embodiment of the application, when the power supply voltage is lower than the first sub-threshold, the pull-down unit is started to pull down the control voltage of the power transistor in the high-side switch; and when the power supply voltage is lower than the second sub-threshold, closing the pull-down unit, and opening the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch.
According to another embodiment of the application, when the power supply voltage is lower than the first sub-threshold, the pull-down unit is started to pull down the control voltage of the power transistor in the high-side switch; and when the power supply voltage is lower than the second sub-threshold, keeping the pull-down unit in an opening state, and opening the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch.
According to an embodiment of the present application, a pull-down capability of a pull-down enhancing unit is higher than that of a pull-down unit.
By adopting the scheme of the application, the speed of the high-side switch for turning off the power transistor and the current leakage of the external load, particularly the inductive load when the power supply is in an abnormal working state can be effectively improved. By designing and controlling a specific protection structure under specific conditions, the influence of an abnormal working state on other modules of the whole circuit is reduced while interference and radiation which can obviously influence the work of equipment are not generated, the process and the manufacturing cost for modifying the whole external circuit for protecting a high-side switch and a part of circuits are reduced, and the protection method of the high-side switch is more generally applicable.
The above-described embodiments are provided for illustrative purposes only and are not intended to be limiting, and various changes and modifications may be made by those skilled in the art without departing from the scope of the present disclosure, and therefore, all equivalent technical solutions should fall within the scope of the present disclosure.
Claims (12)
1. A high-side switch, comprising:
the undervoltage detection unit is configured to compare a power supply signal of the high-side switch with a preset threshold value and output an undervoltage protection signal according to a comparison result;
a power transistor, a first pole of which is coupled with a power supply and receives a power supply signal of the high-side switch, and a second pole of which is coupled with an external load;
the control module is coupled to the control electrode of the power transistor and at least comprises a pull-down unit and a pull-down enhancement unit and is configured to pull down the control voltage of the power transistor by using the pull-down unit and/or the pull-down enhancement unit under the control of the under-voltage protection signal;
the overvoltage protection unit is coupled between the power supply and the ground and configured to start working and discharge the voltage between the power supply and the ground when the voltage between the power supply and the ground is greater than an overvoltage threshold voltage.
2. The high side switch of claim 1, wherein the control module further comprises
A driving unit configured to receive the power supply signal and provide a driving voltage to the pull-down unit and the gate of the power transistor.
3. The high side switch of claim 2, wherein
The pull-down unit comprises a first controlled current source, the first controlled current source is coupled between a control electrode and a second electrode of the power transistor and is controlled by the control module to pull down a control electrode voltage of the power transistor;
the pull-down enhancement unit comprises a second controlled current source, the second controlled current source is coupled between the control electrode and the second electrode of the power transistor, and the control module is used for controlling to pull down the control voltage of the power transistor.
4. The high side switch of claim 2, wherein
The pull-down unit comprises a third controlled current source coupled between the control electrode and the second electrode of the power transistor, when the power supply signal is lower than the preset threshold value, the undervoltage protection signal is effective, the third controlled current source starts to work, and the control electrode voltage of the power transistor is pulled down;
the pull-down enhancement unit comprises a fourth controlled current source coupled between the control electrode and the second electrode of the power transistor, when the power signal is lower than the preset threshold value, the under-voltage protection signal is effective, the fourth controlled current source starts to work, and the control electrode voltage of the power transistor is pulled down.
5. The high-side switch of claim 2, wherein the preset threshold comprises a first sub-threshold and a second sub-threshold, the second sub-threshold being less than the first sub-threshold;
the pull-down unit comprises a fifth controlled current source coupled between the control electrode and the second electrode of the power transistor, when the power supply signal is lower than the first threshold value, the first under-voltage protection signal is effective, the fifth controlled current source starts to work, and the control electrode voltage of the power transistor is pulled down;
the pull-down enhancement unit comprises a sixth controlled current source coupled between the control electrode and the second electrode of the power transistor, when the power supply signal is lower than the second sub-threshold value, the second under-voltage protection signal is effective, the fifth controlled current source stops working, and the sixth controlled current source starts working; or
When the power supply signal is lower than the second sub-threshold, the second under-voltage protection signal is valid, the fifth controlled current source keeps a working state, and the sixth controlled current source starts to work.
6. The high side switch of claim 5, wherein
The current of the sixth controlled current source is greater than the current of the fifth controlled current source.
7. The high side switch of claim 4, wherein
The under-voltage detection unit includes a first comparator, a negative input end of the first comparator is configured to receive the power signal, a positive input end of the first comparator is configured to receive a first reference signal having the preset threshold, and an output end of the first comparator is coupled to the control module.
8. The high side switch of claim 5, wherein
The under-voltage detection unit comprises a second comparator and a third comparator, wherein a negative input end of the second comparator is configured to receive a power supply signal, a positive input end of the second comparator is configured to receive a second reference signal with the first sub-threshold, and an output end of the second comparator is coupled with the control module; the negative input terminal of the third comparator is configured to receive a power signal, the positive input terminal of the third comparator is configured to receive a third reference signal having the second sub-threshold, and the output terminal of the third comparator is coupled to the control module.
9. The high-side switch of claim 2, further comprising a diode having an anode coupled to the second pole of the power transistor and a cathode coupled to the control pole of the power transistor.
10. An electronic device comprising a high-side switch as claimed in claims 1-9.
11. A driving method for protecting a high-side switch comprises
Detecting whether the power supply voltage is lower than a preset threshold value, wherein the preset threshold value is higher than the turn-off voltage of the high-side switch;
and when the power voltage is lower than the preset threshold value, starting the under-voltage protection, and starting the pull-down unit and/or the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch.
12. The driving method according to claim 11, wherein
The preset threshold comprises a first sub-threshold and a second sub-threshold, the second sub-threshold is lower than the first sub-threshold but both are higher than the turn-off voltage of the high-side switch;
when the power supply voltage is lower than the first sub-threshold, starting a pull-down unit to pull down the control electrode voltage of a power transistor in a high-side switch;
when the power supply voltage is lower than the second sub-threshold, closing the pull-down unit, and opening the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch; or
When the power supply voltage is lower than the second sub-threshold, keeping the pull-down unit in an opening state, and opening the pull-down enhancement unit to pull down the control electrode voltage of the power transistor in the high-side switch;
wherein the pull-down enhancing unit has a pull-down capability higher than that of the pull-down unit.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210790885.4A CN115117847A (en) | 2022-07-05 | 2022-07-05 | High-side switch design and driving method thereof |
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| CN202210790885.4A CN115117847A (en) | 2022-07-05 | 2022-07-05 | High-side switch design and driving method thereof |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116248136A (en) * | 2023-03-02 | 2023-06-09 | 苏州纳芯微电子股份有限公司 | Transmitter circuit and bus transceiver with same |
| CN117459042A (en) * | 2023-12-22 | 2024-01-26 | 瓴芯电子科技(无锡)有限公司 | Power switch chip, method for detecting output end state of power switch chip and electronic equipment |
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2022
- 2022-07-05 CN CN202210790885.4A patent/CN115117847A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116248136A (en) * | 2023-03-02 | 2023-06-09 | 苏州纳芯微电子股份有限公司 | Transmitter circuit and bus transceiver with same |
| CN116248136B (en) * | 2023-03-02 | 2024-05-03 | 苏州纳芯微电子股份有限公司 | Transmitter circuit and bus transceiver with same |
| CN117459042A (en) * | 2023-12-22 | 2024-01-26 | 瓴芯电子科技(无锡)有限公司 | Power switch chip, method for detecting output end state of power switch chip and electronic equipment |
| CN117459042B (en) * | 2023-12-22 | 2024-03-08 | 瓴芯电子科技(无锡)有限公司 | Power switch chip, method for detecting output end state of power switch chip and electronic equipment |
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