CN217087506U

CN217087506U - Load driving circuit, PCB and electronic device

Info

Publication number: CN217087506U
Application number: CN202123376570.5U
Authority: CN
Inventors: 李小亮; 张留建; 姚夕林
Original assignee: Continental Automotive Body Electronic System Wuhu Co Ltd
Current assignee: Continental Automotive Body Electronic System Wuhu Co Ltd
Priority date: 2021-12-29
Filing date: 2021-12-29
Publication date: 2022-07-29
Anticipated expiration: 2031-12-29

Abstract

The utility model provides a load drive circuit, including first input and first output, load drive circuit still includes switch circuit and current-limiting output circuit, set up between first input and first output after switch circuit and current-limiting output circuit establish ties, current-limiting output circuit is connected with first power, switch circuit is used for switching on or breaking off current-limiting output circuit according to control signal, current-limiting output circuit is used for the restriction to follow the electric current of first output, when the electric current of output is greater than or equal to the setting value, stop output. The utility model discloses still provide PCB board and electron device. The utility model provides a load drive circuit, PCB board and electron device adopts the current-limiting output circuit that discrete component constitutes, realizes preventing the short circuit and prevents the transposition, can reach the influence that the internal circuit does not receive the load anomaly, can save the cost again.

Description

Load driving circuit, PCB and electronic device

Technical Field

The utility model relates to an automotive filed, concretely relates to load drive circuit, PCB board and electron device.

Background

At present, the instrument drives the circuit of an external load (such as an indicator light, a motor and the like) through a connector, and a high-side driving chip (short circuit prevention/reverse connection prevention and the like) with a protection circuit function is mainly adopted, such as VN7050/INA194, so that the cost of the instrument is correspondingly increased.

Disclosure of Invention

To the problem that exists among the prior art, the utility model aims to solve the problem that a load drive circuit is provided, the current-limiting output circuit who adopts discrete component to constitute realizes preventing the short circuit and preventing reverse connection, can enough the internal circuit not receive the unusual influence of load, can save the cost again.

The utility model provides a load drive circuit, including first input and first output, load drive circuit still includes switch circuit and current-limiting output circuit, set up between first input and first output after switch circuit and current-limiting output circuit establish ties, current-limiting output circuit is connected with first power, switch circuit is used for switching on or breaking off current-limiting output circuit according to control signal, current-limiting output circuit is used for the restriction to follow the electric current of first output, when the electric current of output is greater than or equal to the setting value, stop output.

Furthermore, the current-limiting output circuit comprises a voltage division circuit, a second triode, a third triode, a fourth resistor and a fifth resistor, the second triode and the third triode are PNP pipes, the base of the second triode is connected to the first power source through the fourth resistor and the fifth resistor, the collector is connected with a voltage division point of the voltage division circuit, the emitter is directly connected with the first power source, the base of the third triode is connected with the voltage division point of the voltage division circuit, the collector is connected with the first output end, and the emitter is connected to the first power source through the fifth resistor.

Further, the current-limiting output circuit comprises a voltage division circuit, a second triode, a third triode and a fifth resistor, the second triode and the third triode are PNP tubes, the second triode is provided with a built-in current-limiting resistor, the base of the second triode is connected to the first power supply through the fifth resistor, the collector is connected with a voltage division point of the voltage division circuit, the emitter is directly connected with the first power supply, the base of the third triode is connected with the voltage division point of the voltage division circuit, the collector is connected with the first output end, and the emitter is connected to the first power supply through the fifth resistor.

Further, the resistance value of the fifth resistor Is Vbe/Is, where Vbe Is a conduction voltage of the second triode, and Is a set value of the current output through the first output terminal.

Furthermore, the load driving circuit further comprises a second capacitor, the second capacitor is used for absorbing the peak voltage, and the second capacitor is arranged between the output end of the current-limiting output circuit and the ground.

Further, the load driving circuit includes a first diode for preventing reverse voltage injection, an anode of the first diode is connected to the output terminal of the current-limiting output circuit, and a cathode of the first diode is connected to the first output terminal.

Further, the switching circuit comprises a first triode, the first triode is an NPN (negative-positive-negative) transistor, a base electrode of the first triode is connected with the first input end through a first resistor and is connected with the ground through a first capacitor, a collector electrode is an output end of the switching circuit, and an emitter electrode is connected with the ground.

The utility model also provides a PCB board is provided with above-mentioned load drive circuit on the PCB board.

Furthermore, a connector is further arranged on the PCB, and the first output end of the load driving circuit is connected with an output terminal of the connector.

The utility model also provides an electronic device, including above-mentioned PCB board.

Compared with the prior art, the utility model provides a load drive circuit, PCB board and electron device has following beneficial effect: the current-limiting output circuit formed by discrete elements realizes short circuit prevention and reverse connection prevention, and can not only prevent the internal circuit from being influenced by load abnormity, but also save the cost.

Drawings

Fig. 1 is a schematic view of a PCB board of an embodiment of the present invention;

fig. 2 is a schematic diagram of a load driving circuit of an embodiment of the present invention;

fig. 3 is a schematic diagram of a load driving circuit according to another embodiment of the present invention.

Detailed Description

The electronic device, such as a meter, of an embodiment of the present invention includes a housing (not shown) and a PCB disposed in the housing. In other embodiments, an infotainment system, etc.

As shown in fig. 1, the PCB is provided with a controller Ctl, a load driving circuit CDr and a connector Con, the load driving circuit CDr includes a first input Pi and a first output Po, the first input Pi is connected to a signal output Ps of the controller Ctl, and the first output Po of the load driving circuit CDr is connected to an output terminal of the connector Con.

The load driving circuit CDr is configured to drive an external load connected via a connector Con according to a control signal Ps from the controller Ctl, where the external load is an indicator lamp LD (indicator lamp not belonging to a meter) in the vehicle, and the indicator lamp LD is connected to a first output terminal Po of the load driving circuit CDr via the connector Con.

In other embodiments, the load driving circuit CDr may also be used to drive the load on the PCB according to the control signal Ps from the controller Ctl, and in this case, the load does not need to be connected through a connector.

As shown in fig. 2, the load driving circuit CDr includes a switching circuit SW and a current-limiting output circuit LC, the switching circuit SW and the current-limiting output circuit LC are connected in series and then disposed between the first input terminal Pi and the first output terminal Po, the current-limiting output circuit LC Is connected to the first power supply Vcc, the switching circuit SW Is configured to turn on or off the current-limiting output circuit LC according to the control signal S, the current-limiting output circuit LC Is configured to limit the current output from the first output terminal Po, and when the output current Is greater than or equal to the setting value Is, the output Is stopped.

The switching circuit SW includes a first transistor T1, the first transistor T1 is an NPN transistor, a base of the first transistor T1 is connected to the first input Pi through a first resistor R1 and is connected to ground through a first capacitor C1, a collector is an output terminal of the switching circuit SW, and an emitter is connected to ground. In this embodiment, the resistance range of the first resistor R1 may be 1k Ω to 10k Ω, and the value of the first capacitor C1 is about 0.1 nF.

In other embodiments, different switching circuits may be used as long as they can switch according to the control signal.

The current-limiting output circuit LC comprises a voltage division circuit, a second transistor T2, a third transistor T3, a fourth resistor R4 and a fifth resistor R5.

The voltage dividing circuit is composed of a second resistor R2 and a third resistor R3, the resistance range of the second resistor R2 and the third resistor R3 can be 10k omega-50 k omega, and the voltage dividing circuit is arranged between the first power supply Vcc and the collector of the first triode T1, which is the output end of the switch circuit SW.

The base of the second transistor T2 is connected to the first power supply Vcc through a fourth resistor R4 and a fifth resistor R5, the collector is connected to the voltage dividing point of the voltage dividing circuit, and the emitter is directly connected to the first power supply Vcc.

The base of the third transistor T3 is connected to the voltage dividing point of the voltage dividing circuit, the collector is connected to the first output terminal Po, and the emitter is connected to the first power supply Vcc through the fifth resistor R5.

The fourth resistor R4 is used to limit the base current of the second transistor T2 to protect the second transistor T2. In other embodiments, the second transistor may also be a transistor with a built-in current-limiting resistor, and in this case, the fourth resistor is not required.

The resistance value of the fifth resistor R5 Is Vbe/Is, where Vbe Is the on-state voltage of the second transistor T2, Is the set value of the current output through the first output terminal Po, and when the output current Is greater than or equal to the set value Is, the current-limiting output circuit LC stops outputting.

When the control signal output end Ps of the controller Ctl outputs a high level, that is, the first input end Pi of the load driving circuit CDr is a high level, at this time, the first transistor T1 is turned on, the third transistor T3 is turned on, the first power supply Vcc supplies power to the external load-indicator LD through the fifth resistor R5, the third transistor T3 and the first diode D1, and the indicator LD is turned on.

When the control signal output end Ps of the controller Ctl outputs a low level, that is, the first input end Pi of the load driving circuit CDr is a low level, at this time, the first triode T1 is turned off, the third triode T3 is turned off, the current limiting output circuit LC stops outputting from the first output end Po, and the indicator light LD is turned off.

When the external load changes, such as short circuit, so that the current passing through the fifth resistor R5 increases, the voltage drop exceeds the conducting voltage of the base of the second triode T2, at this time, the second triode T2 is turned on, the third triode T3 is turned off, and the current-limiting output circuit LC stops outputting from the first output terminal Po, thereby achieving the purpose of limiting the output current to protect the instrument.

The control signal may be a high-low level (e.g., high active) or a pulse width modulation signal, and when the control signal is a pulse width modulation signal with different duty ratios, the control signal controls the on/off time of the first transistor T1, and further controls the on/off time of the third transistor T3, so as to adjust the power of the external load.

As shown in fig. 3, the load driving circuit CDr further includes a first diode D1 for preventing reverse voltage injection, and the anode of the first diode D1 is connected to the output terminal of the current-limiting output circuit LC, i.e., the anode of the first diode D1 is connected to the collector of the third transistor T3, and the cathode is connected to the first output terminal Po.

The load driving circuit CDr further includes a second capacitor C2, the second capacitor C2 is used for absorbing spike voltage to avoid damaging the internal circuit of the instrument, and the second capacitor C2 is disposed between the output end of the current-limiting output circuit LC and ground, that is, the second capacitor C2 is disposed between the collector of the third transistor T3 and ground.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited thereto. Various changes and modifications can be made by one skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention is to be determined by the appended claims.

Claims

1. A load driving circuit is characterized by comprising a first input end and a first output end, and further comprising a switch circuit and a current-limiting output circuit, wherein the switch circuit and the current-limiting output circuit are connected in series and then are arranged between the first input end and the first output end, the current-limiting output circuit is connected with a first power supply, the switch circuit is used for switching on or switching off the current-limiting output circuit according to a control signal, the current-limiting output circuit is used for limiting current output from the first output end, and when the output current is larger than or equal to a set value, the output is stopped.

2. The load driving circuit according to claim 1, wherein the current-limiting output circuit comprises a voltage divider circuit, a second transistor, a third transistor, a fourth resistor and a fifth resistor, the second transistor and the third transistor are PNP transistors, a base of the second transistor is connected to the first power supply through the fourth resistor and the fifth resistor, a collector is connected to a voltage dividing point of the voltage divider circuit, an emitter is directly connected to the first power supply, a base of the third transistor is connected to the voltage dividing point of the voltage divider circuit, the collector is connected to the first output terminal, and the emitter is connected to the first power supply through the fifth resistor.

3. The load driving circuit according to claim 1, wherein the current limiting output circuit comprises a voltage divider circuit, a second transistor, a third transistor, and a fifth resistor, the second and third transistors being PNP transistors, the second transistor having a built-in current limiting resistor, a base of the second transistor being connected to the first power source through the fifth resistor, a collector being connected to a voltage dividing point of the voltage divider circuit, an emitter being directly connected to the first power source, a base of the third transistor being connected to the voltage dividing point of the voltage divider circuit, the collector being connected to the first output terminal, and the emitter being connected to the first power source through the fifth resistor.

4. The load driving circuit according to claim 2 or 3, wherein the resistance of the fifth resistor Is Vbe/Is, where Vbe Is a turn-on voltage of the second transistor, and Is a set value of a current output through the first output terminal.

5. The load driving circuit of claim 1, further comprising a second capacitor configured to absorb spike voltages, the second capacitor being disposed between the output of the current limited output circuit and ground.

6. The load driving circuit of claim 1, wherein the load driving circuit comprises a first diode for preventing reverse voltage injection, the first diode having an anode connected to the output of the current limited output circuit and a cathode connected to the first output.

7. The load driving circuit of claim 1, wherein the switching circuit comprises a first transistor, the first transistor is an NPN transistor, a base of the first transistor is connected to the first input terminal through a first resistor and to ground through a first capacitor, a collector is an output terminal of the switching circuit, and an emitter is connected to ground.

8. A PCB board, wherein the load driving circuit of any one of claims 1 to 7 is provided on the PCB board.

9. The PCB of claim 8, wherein the PCB is further provided with a connector, and the first output terminal of the load driving circuit is connected to an output terminal of the connector.

10. An electronic device, characterized in that the electronic device comprises the PCB board of claim 8 or 9.