Direct current reverse connection protection circuit with current limiting protection

Abstract

The utility model relates to a direct current reverse connection protection circuit with current-limiting protection, which comprises a power supply input end, a power supply output end, a reverse connection protection MOS tube Q1, a current-limiting MOS tube Q2, a bias resistor R1, a diode D1 and a current detection resistor R2, the drain electrode of the reverse connection protection MOS tube Q1 is connected with the power supply input end, the source electrode of the reverse connection protection MOS tube Q1 is connected with the negative electrode of the diode D1 and one end of the current detection resistor R2, and the negative electrode of the diode D1 is connected with the negative electrode of the current detection resistor R2. A grid electrode of the reverse connection protection MOS tube Q1 is connected with a positive electrode of the diode D1, one end of the bias resistor R1 and a grid electrode of the current limiting MOS tube Q2, the other end of the bias resistor R1 is connected with a signal ground, a source electrode of the current limiting MOS tube Q2 is connected with the other end of the current detection resistor R2, and a drain electrode of the current limiting MOS tube Q2 is connected with a power supply output end. The circuit has a current limiting function, and can restrain the surge impact current at the power-on moment.

Description

Technical Field

[0001] The utility model belongs to the technical field of automobile electronics industry, and particularly relates to a direct current reverse connection protection circuit with current limiting protection. Background Art

[0002] Reverse polarity connection of the power supply is a common problem for electronic devices that use direct current. Once the polarity is reversed, not only will the electronic device stop working, but it may also cause damage to the electronic device.

[0003] A commonly used PMOS reverse connection protection circuit currently has a surge current at the power-on moment, the size of which varies with the operating voltage, thus causing damage to the device. Summary of the invention

[0004] The utility model provides a DC reverse connection protection circuit with current limiting protection, so as to suppress surge impact current during power-on, thereby solving the technical problems mentioned in the background technology.

[0005] The technical scheme of the utility model is as follows: a DC reverse connection protection circuit with current limiting protection, comprising: a power input end, a power output end, a reverse connection protection MOS tube Q1, a current limiting MOS tube Q2, a bias resistor R1, a diode D1, and a current sensing resistor R2, wherein the drain of the reverse connection protection MOS tube Q1 is connected to the power input end, the source of the reverse connection protection MOS tube Q1 is connected to the negative electrode of the diode D1 and one end of the current sensing resistor R2, the gate of the reverse connection protection MOS tube Q1 is connected to the positive electrode of the diode D1, one end of the bias resistor R1 and the gate of the current limiting MOS tube Q2, the other end of the bias resistor R1 is connected to the signal ground, the source of the current limiting MOS tube Q2 is connected to the other end of the current sensing resistor R2, and the drain of the current limiting MOS tube Q2 is connected to the power output end.

[0006] Furthermore, the reverse connection protection MOS tube Q1 is a PMOS tube.

[0007] Furthermore, the current limiting MOS tube Q2 is a PMOS tube.

[0008] Furthermore, the diode D1 is a voltage regulator.

[0009] The beneficial effects of the utility model are as follows: the utility model uses fewer components and has a low cost. In addition to the reverse connection protection function, it also has a current limiting function and can suppress surge impact current at the power-on moment. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of the utility model. DETAILED DESCRIPTION

[0011] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. The described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the utility model.

[0012] In an embodiment of the present utility model, Figure 1 It is a structural schematic diagram provided according to the specific structure of a DC reverse connection protection circuit with current limiting protection of the utility model, such as Figure 1 As shown, the utility model includes:

[0013] A power input end, a power output end, a reverse connection protection MOS tube Q1, a current limiting MOS tube Q2, a bias resistor R1, a diode D1, and a current sensing resistor R2, wherein the drain of the reverse connection protection MOS tube Q1 is connected to the power input end, the source of the reverse connection protection MOS tube Q1 is connected to the cathode of the diode D1 and one end of the current sensing resistor R2, the gate of the reverse connection protection MOS tube Q1 is connected to the anode of the diode D1, one end of the bias resistor R1, and the gate of the current limiting MOS tube Q2, the other end of the bias resistor R1 is connected to the signal ground, the source of the current limiting MOS tube Q2 is connected to the other end of the current sensing resistor R2, and the drain of the current limiting MOS tube Q2 is connected to the power output end.

[0014] Wherein, the reverse connection protection MOS tube Q1 is a PMOS tube.

[0015] Wherein, the current limiting MOS tube Q2 is a PMOS tube.

[0016] Wherein, the diode D1 is a voltage regulator.

[0017] like Figure 1 As shown, V IN is the input voltage of the DC power supply, V OUT It is the output voltage after protection by this device. Q1 is a reverse protection MOS tube, which protects the load from damage when the power supply is reversed. D1 is a voltage-stabilizing diode, which is used to protect the gates of Q1 and Q2, and is also used to adjust the current limit value. R1 is the bias resistor of diode D1, which is used to provide voltage-stabilizing bias current. R2 is a current-sensing resistor, which is used to detect the load current and provide negative feedback to participate in the control of the current-limiting MOS tube Q2. Q2 is a voltage-stabilizing MOS tube, which is used to achieve current-limiting protection.

[0018] The specific working principle is as follows:

[0019] The DC reverse connection protection circuit has two functions: forward conduction and reverse cutoff. When a forward DC voltage is applied, the body diode of Q1 is turned on first, and the control voltage is applied to Q1 and Q2 at the same time through D1 and R1 to control the two PMOS tubes to turn on and achieve forward conduction. When a reverse DC voltage is applied, the body diode of Q2 is turned on, and the body diode of Q1 and the control electrode voltage V GS All are in reverse bias state, and the entire PMOS tube Q1 is in cut-off state, thus achieving reverse connection protection.

[0020] Working process of current limiting protection:

[0021] V Z(D1) =V GS +R2*I LOAD

[0022] Thus:

[0023] V GS =V Z(D1) -R2*I LOAD

[0024] Voltage V Z(D1) is stable, so when the load current I LOAD When the control voltage V GS Then it decreases. When V GS Reaching the Miller platform voltage V GS(Plateau) When the voltage is close to , Q2 enters the linear conduction state from the saturated conduction state, thus achieving output current limitation.

[0025] The current limit value can be adjusted by R2:

[0026] I LOAD =(V Z(D1) -V GS(Plateau) ) / R2

[0027] The above parameters are specifically:

[0028] V GS : Control electrode voltage of PMOS tube;

[0029] V GS(Plateau) : Miller platform voltage of PMOS tube control pole;

[0030] V Z(D1) : Rated stable voltage of Zener diode D1;

[0031] I LOAD : Load current.

[0032] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to examples, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A DC reverse connection protection circuit with current limiting protection, characterized in that: include: A power input end, a power output end, a reverse connection protection MOS tube Q1, a current limiting MOS tube Q2, a bias resistor R1, a diode D1, and a current sensing resistor R2, wherein the drain of the reverse connection protection MOS tube Q1 is connected to the power input end, the source of the reverse connection protection MOS tube Q1 is connected to the cathode of the diode D1 and one end of the current sensing resistor R2, the gate of the reverse connection protection MOS tube Q1 is connected to the anode of the diode D1, one end of the bias resistor R1, and the gate of the current limiting MOS tube Q2, the other end of the bias resistor R1 is connected to the signal ground, the source of the current limiting MOS tube Q2 is connected to the other end of the current sensing resistor R2, and the drain of the current limiting MOS tube Q2 is connected to the power output end.

2. The DC reverse connection protection circuit with current limiting protection according to claim 1, characterized in that: The reverse connection protection MOS tube Q1 is a PMOS tube.

3. The DC reverse connection protection circuit with current limiting protection according to claim 1, characterized in that: The current limiting MOS tube Q2 is a PMOS tube.

4. The DC reverse connection protection circuit with current limiting protection according to claim 1, characterized in that: The diode D1 is a voltage regulator.

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