Low-side driving circuit

Abstract

The utility model discloses a low-side driving circuit, which comprises a first driving circuit and a second driving circuit, the first driving circuit is connected with the second driving circuit through a diode, the first driving circuit is electrically connected with a load, the load is electrically connected with a power interface, the first driving circuit is connected with a digital-to-analog converter, and the digital-to-analog converter is connected with the second driving circuit. And the second driving circuit is connected with a controller. According to the low-side driving circuit provided by the utility model, the first driving circuit and the second driving circuit are connected through the diode, so that the reverse connection prevention function of the circuit can be realized, and the use safety is improved.

Description

Technical Field

[0001] This utility model belongs to the field of automotive electronic controller technology, specifically relating to a low-side drive circuit. Background Technology

[0002] Low-side drive circuits operate by controlling the switching on and off of a switch through a closed ground wire, thereby controlling the load switch. Current design trends primarily focus on improving the driving capability of the output transistor, with design directions mainly revolving around improving the transistor's turn-on time and drive current capability.

[0003] However, existing low-side drive circuits have many shortcomings. On the one hand, their functions are relatively simple, with most only possessing basic driving functions and severely lacking effective diagnostic capabilities for external loads. Even those circuits that do have load diagnostic functions are extremely limited and cannot comprehensively cover various common diagnostic needs such as short circuit to power supply, short circuit to ground, and open circuit.

[0004] On the other hand, existing designs often neglect circuit protection functions. Important protection mechanisms such as overcurrent protection and reverse connection protection are often not adequately considered in many designs. Furthermore, as the requirements for leakage current in automotive electronics become increasingly stringent, existing low-side driver chips generally suffer from excessively high leakage current, which undoubtedly limits their further application and development in related fields. Utility Model Content

[0005] The purpose of this invention is to propose a low-side drive circuit that solves the problem of lack of diagnostic and reverse connection protection functions in low-side drive circuits.

[0006] Therefore, this utility model provides a low-side driving circuit, including: a first driving circuit and a second driving circuit, the first driving circuit and the second driving circuit are connected by a diode, the first driving circuit is electrically connected to a load, the load is electrically connected to a power interface, the first driving circuit is connected to a digital-to-analog converter, and the second driving circuit is connected to a controller.

[0007] Preferably, the first driving circuit includes a first resistor, a second resistor, and a first transistor. The first resistor is electrically connected to the second resistor, the second resistor is electrically connected to the first transistor, and the first transistor is electrically connected to the diode.

[0008] Preferably, the first transistor includes a first transistor A and a first transistor B, wherein the first transistor A is connected to the first transistor B, the second resistor and the diode respectively.

[0009] Preferably, an eighth resistor is connected between the first transistor B and the diode.

[0010] Preferably, the first transistor B is connected to a seventh resistor, and the two ends of the seventh resistor are respectively connected to the power supply and ground.

[0011] Preferably, a first capacitor is connected between the first resistor and the second resistor, and the first capacitor is grounded.

[0012] Preferably, a fifth resistor is connected between the first resistor and the second resistor, and the fifth resistor is grounded.

[0013] Preferably, a ninth resistor is connected between the second resistor and the first transistor, and the ninth resistor is connected to a power supply.

[0014] Preferably, the second driving circuit includes a third resistor, a second transistor, a third transistor, and a fourth resistor. The second transistor is electrically connected to the third resistor, the fourth resistor, and the diode, respectively. The third transistor is electrically connected to the third resistor and the fourth resistor, respectively. The third transistor is grounded, and the fourth resistor is grounded.

[0015] Preferably, a sixth resistor is provided between the third resistor and the third transistor, and the sixth resistor is grounded.

[0016] Beneficial effects:

[0017] 1. This utility model provides a low-side driving circuit that connects the first driving circuit and the second driving circuit through a diode, thereby achieving the circuit's reverse connection protection function and improving safety during use.

[0018] 2. This utility model uses a power supply, a second resistor, a fifth resistor, a ninth resistor, and a first transistor to form a diagnostic circuit. When the signal input to the controller is low, the voltage division value of the fifth resistor is collected by a digital-to-analog converter. This allows for three diagnostic functions for the externally connected load RL1: "load open circuit", "interface short circuit to ground", and "interface short circuit to power supply".

[0019] 3. This utility model forms a protection circuit through a second transistor, a third transistor, and a fourth resistor. When the voltage is over-voltage or the current is over-current, the base voltage of the third transistor increases, causing the third transistor to turn on, and the base of the second transistor is pulled down to ground, thereby realizing the turn-off control of the second transistor and realizing the protection function of the circuit.

[0020] 4. In this utility model, when the controller is not working, there is no power output, and both the first transistor and the second transistor are in the off state. At this time, the current is in the open circuit state, and no static power consumption is generated in the circuit. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 The circuit diagram is shown in Embodiment 1 of the low-side driving circuit provided by this utility model.

[0023] In the diagram, D1 is a diode, R1 is the first resistor, R2 is the second resistor, R3 is the third resistor, R4 is the fourth resistor, R5 is the fifth resistor, R6 is the sixth resistor, R7 is the seventh resistor, R8 is the eighth resistor, R9 is the ninth resistor, Q1 is the first transistor, Q2 is the second transistor, Q3 is the third transistor, C1 is the first capacitor, TP1 is the first voltage measurement point, and TP2 is the second voltage measurement point. Detailed Implementation

[0024] The following detailed description of preferred embodiments of the present invention, along with the included examples, will make the content of the present invention more readily understood. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of any conflict, the definitions in this specification shall prevail.

[0025] Example 1:

[0026] Provided such as Figure 1 The low-side driving circuit shown includes: a first driving circuit and a second driving circuit. The first driving circuit and the second driving circuit are connected through a diode D1. The first driving circuit is electrically connected to a load RL1. The load RL1 is electrically connected to a power interface VBAT. The first driving circuit is connected to a digital-to-analog converter (ADC). The second driving circuit is connected to a controller.

[0027] The first driving circuit includes a first resistor R1, a second resistor R2, and a first transistor Q1. The first resistor R1 is electrically connected to the second resistor R2, the second resistor R2 is electrically connected to the first transistor Q1, and the first transistor Q1 is electrically connected to the diode D1. The first transistor Q1 includes a first transistor Q1A and a first transistor Q1B. The first transistor Q1A is connected to the first transistor Q1B, the second resistor R2, and the diode D1. An eighth resistor R8 is connected between the first transistor Q1B and the diode D1. The first transistor Q1B is connected to a seventh resistor R7, with its two ends connected to a power supply and ground, respectively. A first capacitor C1 is connected between the first resistor R1 and the second resistor R2, and the first capacitor C1 is grounded. A fifth resistor R5 is connected between the first resistor R1 and the second resistor R2, and the fifth resistor R5 is grounded. A ninth resistor R9 is connected between the second resistor R2 and the first transistor Q1, and the ninth resistor R9 is connected to a power supply. A first voltage measurement point TP1 is provided between the fifth resistor R5 and the second resistor R2, and a second voltage measurement point TP2 is provided between the first transistor Q1 and the diode.

[0028] The second driving circuit includes a third resistor R3, a second transistor Q2, a third transistor Q3, and a fourth resistor R4. The second transistor Q2 is electrically connected to the third resistor R3, the fourth resistor R4, and the diode D1. The third transistor Q3 is electrically connected to the third resistor R3 and the fourth resistor R4. The third transistor Q3 is grounded, and the fourth resistor R4 is also grounded. A sixth resistor R6 is placed between the third resistor R3 and the third transistor Q3, and the sixth resistor R6 is grounded.

[0029] Working principle:

[0030] Low-side drive control function: When the control signal input to the second transistor Q2 is high level, the second transistor Q2 turns on, and the circuit is turned on, driving the externally connected load RL1.

[0031] The power supply is 12V VBAT. The second MOSFET, Q2, has a current capability of Id = 3A. The third MOSFET, Q3, is selected with a turn-on voltage Von = 0.8V and an output current Io = 500mA. The external load RL1 is a relay with a resistance of 85Ω and a pull-in voltage of 7.2V. The voltage divider resistors are configured with a resistance of 2Ω based on the circuit conditions.

[0032] When the power supply VBAT provides 12V, the current flowing through the fourth resistor R4, IR4 = VBAT / (RLoad+R4) = 12V / (85+2)Ω≈138mA. The current limit of the drive circuit, Imax = Von / R4 = 0.8V / 2Ω = 400mA. When the drive circuit current reaches 400mA, the base voltage of the third transistor Q3 reaches the 0.8V turn-on voltage, making the collector and emitter of the third transistor Q3 fully conductive. This causes the base of the second transistor Q2 to be pulled down to ground, and the second transistor Q2 is in the cutoff state, thus turning off the drive circuit and realizing the circuit protection function.

[0033] Circuit diagnostic function:

[0034] When the circuit power supply voltage VBAT is 12V, and the second transistor Q2 is turned off, the analog signal of the ADC pin is collected for sampling and diagnosis.

[0035] Based on the external load RL1, the voltage division ratio between TP1 and TP2 is reasonably designed by selecting the resistance values ​​of the second resistor R2 and the fifth resistor R5: V(TP2)=V(TP1)*[R5 / (R2+R5)].

[0036] Choose a 5V VCC power supply, resistors R9=4.7K, R2=560Ω, R5=330Ω, and RL1=85Ω.

[0037] When RL1 is connected normally:

[0038] V(TP1)= VBAT / (R2+R5+RL1)*R5=12V / (560+330+85)Ω*330Ω≈4.06 V

[0039] VBAT-V(TP2)=12V- V(TP1)*[R5 / (R2+R5)]=1.046V

[0040] When RL1 load RL1 is open circuit:

[0041] V(TP1)=VCC / (R2+R5+R9)*R5=12V / (560+330+4700)Ω*330Ω≈0.3 V

[0042] VBAT-V(TP2)=12V- V(TP1)*[R5 / (R2+R5)]=11.2V

[0043] When the interface is short-circuited to ground:

[0044] V(TP1) = 0V

[0045] VBAT - V(TP2) = 12V

[0046] Interface shorted to power supply:

[0047] V(TP1) = VCC / (R2 + R5)*R5 = 12V / (560 + 330)Ω * 330Ω ≈ 4.45 V

[0048] VBAT - V(TP2) = 0V

[0049] 1. Load RL1 open - circuit (OP) fault diagnosis: When 0V < V(TP1) < 0.5V is collected, it is determined that the load RL1 has an open - circuit fault;

[0050] 2. Interface shorted to ground (STG) diagnosis: When V(TP1) < 0.1V, it is determined that the interface has a short - circuit to ground (STG) fault;

[0051] 3. Interface shorted to power supply (STB) fault diagnosis: When the threshold |VBAT - V(TP2)| < 0.5V is set, it is determined that the interface has a short - circuit to power supply (STB) fault.

[0052] Finally, it should be noted that: The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: They can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A low-side drive circuit, characterized by, The utility model relates to a driving circuit, which comprises: a first driving circuit and a second driving circuit connected by a diode, the first driving circuit being electrically connected to a load, the load being electrically connected to a power supply, the first driving circuit being connected to a digital-to-analog converter, and the second driving circuit being connected to a controller.

2. The low-side driver circuit of claim 1, wherein, The first driving circuit comprises a first resistor, a second resistor, and a first triode, the first resistor being electrically connected to the second resistor, the second resistor being electrically connected to the first triode, and the first triode being electrically connected to the diode.

3. The low-side driver circuit of claim 2, wherein, The first triode comprises a first triode A and a first triode B, the first triode A being connected to the first triode B, the second resistor, and the diode.

4. The low-side driver circuit of claim 3, wherein, An eighth resistor is connected between the first triode B and the diode.

5. The low-side driver circuit of claim 3, wherein, The first triode B is connected to a seventh resistor, the two ends of the seventh resistor being connected to a power supply and ground, respectively.

6. The low-side driver circuit of claim 2, wherein, A first capacitor is connected between the first resistor and the second resistor, and the first capacitor is grounded.

7. The low-side driver circuit of claim 2, wherein, A fifth resistor is connected between the first resistor and the second resistor, and the fifth resistor is grounded.

8. The low-side driver circuit of claim 2, wherein, A ninth resistor is connected between the second resistor and the first triode, and the ninth resistor is connected to a power supply.

9. The low-side driver circuit of claim 1, wherein, The second driving circuit comprises a third resistor, a second triode, a third triode, and a fourth resistor, the second triode being electrically connected to the third resistor, the fourth resistor, and the diode, respectively, the third triode being electrically connected to the third resistor and the fourth resistor, respectively, the third triode being grounded, and the fourth resistor being grounded.

10. The low-side driver circuit of claim 9, wherein, A sixth resistor is provided between the third resistor and the third triode, and the sixth resistor is grounded.

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