High-side switch over-current protection circuit

Abstract

The utility model provides a high-side switch overcurrent protection circuit, which comprises a switch control circuit, a drive circuit, a sampling resistor, a feedback circuit and a hiccup control circuit, the hiccup control circuit comprises a capacitor C2 and a resistor R8, one end of the capacitor C2 is connected to a node of the feedback circuit, and the other end of the capacitor C2 is connected with the resistor R8 to form a t1 delay circuit and then is grounded. The scheme that the capacitor C2 is added in the overcurrent protection circuit is adopted, the C2 is matched with the resistor R8 and the resistor R4, so that the hiccup period is greatly adjusted, the temperature influence is reduced, meanwhile, the hiccup period is adjusted by using the time constants of the resistor and the capacitor, the dependence on the characteristics of the transistor is reduced, and the reliability of the overcurrent protection circuit is improved. Therefore, the current protection interval can be basically stabilized at about 50ms at different temperatures, and the stability and the reliability of the circuit are remarkably improved.

Description

Technical Field

[0001] The utility model relates to the technical field of output driving circuits, and particularly to a high-side switch overcurrent protection circuit. Background Art

[0002] The high-side switch overcurrent protection circuit is an electronic protection mechanism used to monitor and control the current flow in the circuit, preventing damage to the high-side switch or the load it drives in the event of overcurrent. In the prior art, measures such as quickly responding to overcurrent events and disconnecting the power supply or reducing the load current are generally taken to ensure the safe and stable operation of the circuit and equipment.

[0003] Patent CN117155358A discloses a high-side output driving circuit with hiccup-mode overload and overcurrent protection, which proposes to achieve overload and overcurrent protection of the driving circuit while keeping the circuit cost relatively low by setting a circuit structure with hiccup mode.

[0004] However, it still has the following problems: ① The hiccup period adjustment is greatly affected by the MOS transistor Q3; ② The adjustment range of the hiccup period is small and greatly affected by temperature.

[0005] Therefore, it is necessary to design a protection circuit with a stable hiccup period, a long hiccup period, and low temperature influence. Summary of the Utility Model

[0006] Aiming at the deficiencies of the prior art, the purpose of the utility model is to provide a high-side switch overcurrent protection circuit to solve the problems raised in the above background art. The utility model adds a capacitor C2 to the hiccup control circuit to extend the off time of the high-side switch T1, achieving the purpose of widely adjusting the hiccup period and solving the problems in the prior art.

[0007] To achieve the above purpose, the utility model is realized by the following technical solutions: A high-side switch overcurrent protection circuit includes:

[0008] A switch control circuit, a driving circuit, a sampling resistor, a feedback circuit, and a hiccup control circuit, wherein,

[0009] The switch control circuit receives an input signal and generates a signal to control the high-side switch T1; the driving circuit receives the output signal of the switch control circuit and drives the high-side switch T1 to perform on-off operations; the sampling resistor is connected to the switch control circuit through the hiccup control circuit and the feedback circuit in sequence to achieve overcurrent protection.

[0010] The hiccup control circuit includes a capacitor C2 and a resistor R8. One end of the capacitor C2 is connected to the node of the feedback circuit, and the other end is connected to the resistor R8 to form a t1 delay circuit and then grounded.

[0011] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0012] To solve the problems in the prior art that the hiccup cycle adjustment is greatly affected by the transistor Q3, the adjustment range is limited, and the stability is poor due to the influence of temperature, the present utility model adopts a scheme of adding a hiccup control capacitor C2 in the overcurrent protection circuit. Through the cooperation of C2 with resistors R8 and R4, a large adjustment of the hiccup cycle and a reduction of the influence of temperature are achieved. At the same time, the time constant of the resistor and capacitor is used to adjust the hiccup cycle, reducing the dependence on the transistor characteristics. Thus, the current protection interval can be basically stabilized at about 50 ms at different temperatures (such as -40°C, 20°C, 80°C), significantly improving the stability and reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The disclosure of the present utility model will be described with reference to the accompanying drawings. It should be understood that the drawings are only for illustrative purposes and are not intended to limit the protection scope of the present utility model. In the drawings, the same reference numerals are used to refer to the same components. Among them:

[0014] Figure 1 is a schematic structural diagram of the high-side switch overcurrent protection circuit proposed in an embodiment of the present utility model;

[0015] Figure 2 is a principle block diagram of the high-side switch overcurrent protection circuit proposed in an embodiment of the present utility model;

[0016] Figure 3 is a simulation current diagram of the high-side switch overcurrent protection circuit proposed in an embodiment of the present utility model, which always maintains the current protection interval stable at about 50 ms at different temperatures. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] It is easy to understand that according to the technical solution of the present utility model, without changing the essential spirit of the present utility model, those of ordinary skill in the art can propose various interchangeable structural forms and implementation methods. Therefore, the following detailed description and the accompanying drawings are only illustrative of the technical solution of the present utility model and should not be regarded as all of the present utility model or as a limitation or restriction on the technical solution of the present utility model.

[0018] It should be noted that the hiccup mode overcurrent protection is a key safety feature in the high-side output drive circuit, aiming to provide protection to avoid damage when the circuit encounters overload or short circuit.

[0019] In patent CN117155358A, the hiccup period is mainly affected by the parameters of capacitor C1 and resistors R2 and R3. The above-mentioned components jointly determine the discharge rate of capacitor C1, thereby affecting the length of the hiccup period. Specifically, the on and off states of MOS transistor Q3 directly determine the generation of hiccup pulses. If the conduction threshold of MOS transistor Q3 is high or the response speed is slow, it will cause a delay in triggering the hiccup mode or a decrease in frequency, thereby affecting the regulation of the hiccup period.

[0020] In addition, the adjustment range of the hiccup period is limited by the selection ranges of capacitor C1 and resistors R2 and R3. If the selection ranges of the above components are limited, the adjustable range of the hiccup period will also be limited. At the same time, in a high-temperature environment, the resistance value of the resistor decreases, and the threshold voltage of the MOS transistor also changes, which causes the hiccup period to become shorter or unstable, thereby affecting the performance and reliability of the entire protection circuit.

[0021] Based on this, as Figures 1-3 shown, as an embodiment of the present utility model, the present utility model provides a technical solution: a high-side switch overcurrent protection circuit, including:

[0022] a switch control circuit, a drive circuit, a sampling resistor, a feedback circuit, and a hiccup control circuit. Among them,

[0023] The switch control circuit receives an input signal and generates a signal for controlling high-side switch T1; the drive circuit receives the output signal of the switch control circuit and drives high-side switch T1 to perform on / off operations; the sampling resistor is connected to the switch control circuit through the hiccup control circuit and the feedback circuit in sequence to achieve overcurrent protection.

[0024] In an embodiment of the present utility model, the hiccup control circuit includes a hiccup control capacitor C2 and a hiccup control resistor R8. One end of the hiccup control capacitor C2 is connected to the node of the feedback circuit, and the other end is connected to the hiccup control resistor R8 to form a t1 delay circuit and then grounded. Specifically, in implementation, one end of the hiccup control capacitor C2 is connected to the cathode of Schottky diode SD1 in the feedback circuit, and the other end is connected to the collector of transistor T6 to store energy and provide a delay response in the case of overcurrent.

[0025] The switch control circuit and the drive circuit include resistor R1, resistor R2, resistor R4, and MOS transistor T4. Among them, the gate of MOS transistor T4 receives the signal of control signal source VG2, the source is grounded, and the drain is connected to the gate of high-side switch T1 after being connected in series with resistor R2; the source of high-side switch T1 is grounded, and the drain is connected to the load; one end of resistor R1 is connected to resistor R2 to form the gate drive circuit of high-side switch T1 to provide an appropriate bias, and the other end is connected to sampling resistor R3 and then grounded; resistor R4 is connected in series between control signal source VG2 and the gate of MOS transistor T4 to limit current and form a t2 delay circuit.

[0026] In an embodiment of the present utility model, the feedback circuit includes a Schottky diode SD1, a transistor T3, and a capacitor C3. Among them, the anode of the Schottky diode SD1 is respectively connected to the collector of the transistor T3 and one end of the capacitor C3, and the cathode is connected to the base of the transistor T6, which is used to quickly respond to the overcurrent situation; the base of the transistor T3 is connected to the sampling resistor R3 to receive the control signal source VG1, the collector is connected to the capacitor C3 to form a charging path, and the emitter is grounded after being connected to the sampling resistor R3; the collector of the transistor T6 is connected to the control signal source VG2, and the emitter is connected to the other end of the capacitor C3 and grounded. When the transistor T6 is turned on, the transistor T6 pulls down the voltage of the control signal source VG2, and the MOS transistors T4 and T1 are turned off.

[0027] As an embodiment of the present utility model, the high-side switch T1 preferably uses a PMOS transistor, the MOS transistor T4 is an NMOS transistor, the transistor T3 is a PNP-type transistor, and the transistor T6 is an NPN-type transistor.

[0028] The circuit working principle of the present utility model is as follows:

[0029] VG2 is a switching signal used to switch T4, thereby starting the switch of T1 to achieve the function of the high-side switch. R3 is used as a sampling resistor. When an overcurrent occurs, the voltage value generated by the current AM1 * R3 is greater than VBE-T1, and the transistor T3 generates a current IC-T3 and charges C3; the voltage of the C3 capacitor rises, and when the VC3 voltage is greater than VBE-SD1 + VBE-T6, T6 will be turned on. When T6 is turned on, it will force the VF2 voltage to be pulled down to about 0.2V. The low voltage turns off T4, thereby turning off T1; when the device T6 is working, C3 will transfer charges to C2, and VC2 = VC3 - VBE-SD1; after T1 is turned off, the current flowing through R3 decreases, resulting in the current IC-T3 of T3 decreasing to 0; since the charge stored in C2 will extend the turn-off time t1, and then enters the charging time t2 of R4 and C2; within the time t1 + t2, it is the turn-off stage of T4; then it enters the process of turning on T4 again, and so on in a cycle.

[0030] Based on the above technical concept, since the present utility model adds a capacitor C2 to extend the turn-off time to achieve the purpose of widely adjusting the hiccup period, it can be understood that the hiccup period of the circuit proposed by the present utility model is mainly determined by the time of t1 + t2, and the t1 time is mainly determined by the capacitor C2 and the resistor R8, and the t2 time is mainly determined by the capacitor C2 and the resistor R4. Since the resistance and capacitance change relatively less than the transistor with temperature, therefore, the present utility model can exhibit better stability characteristics at different temperatures, such as Figure 3As shown, it is a simulated current graph that can keep the current protection interval basically stable at about 50 ms at different temperatures (-40°C, 20°C, 80°C), significantly improving the stability and reliability of the circuit.

[0031] The technical scope of the present utility model is not limited to the content described above. Those skilled in the art can make various deformations and modifications to the above embodiments without departing from the technical idea of the present utility model, and these deformations and modifications shall all fall within the protection scope of the present utility model.

Claims

1. A high-side switch overcurrent protection circuit, characterized in that: Comprising: A switch control circuit, a driving circuit, a sampling resistor, a feedback circuit, and a hiccup control circuit, wherein, The switch control circuit receives an input signal and generates a signal for controlling the high-side switch T1; the driving circuit receives the output signal of the switch control circuit and drives the high-side switch T1 to perform on / off operations; the sampling resistor is sequentially connected to the switch control circuit through the hiccup control circuit and the feedback circuit to achieve overcurrent protection. The hiccup control circuit includes a capacitor C2 and a resistor R8. One end of the capacitor C2 is connected to the node of the feedback circuit, and the other end is connected to the resistor R8 to form a t1 delay circuit and is grounded.

2. The overcurrent protection circuit for a high-side switch according to claim 1, wherein: The switch control circuit and the driving circuit include a resistor R1, a resistor R2, a resistor R4, and an MOS transistor T4, wherein, The gate of the MOS transistor T4 receives the signal of the control signal source VG2, the source is grounded, and the drain is connected to the gate of the high-side switch T1 after being connected in series with the resistor R2; the source of the high-side switch T1 is grounded, and the drain is connected to the load; One end of the resistor R1 is connected to the resistor R2 to form a gate driving circuit for the high-side switch T1 to provide an appropriate bias, and the other end is connected to the sampling resistor R3 and then grounded; The resistor R4 is connected in series between the control signal source VG2 and the gate of the MOS transistor T4 to limit the current and form a t2 delay circuit.

3. The overcurrent protection circuit for a high-side switch according to claim 1, wherein: The feedback circuit includes a Schottky diode SD1, a transistor T3, and a capacitor C3, wherein, The anode of the Schottky diode SD1 is respectively connected to the collector of the transistor T3 and one end of the capacitor C3, and the cathode is connected to the base of the transistor T6, which is used to quickly respond to the overcurrent situation; The base of the transistor T3 is connected to the sampling resistor R3 to receive the control signal source VG1, the collector is connected to the capacitor C3 to form a charging path, and the emitter is connected to the sampling resistor R3 and then grounded; The collector of the transistor T6 is connected to the control signal source VG2, and the emitter is connected to the other end of the capacitor C3 and is grounded. When the transistor T6 is turned on, the transistor T6 pulls down the voltage of the control signal source VG2, and the MOS transistor T4 and the MOS transistor T1 are turned off.

4. The overcurrent protection circuit for a high-side switch according to claim 1, wherein: One end of the capacitor C2 is connected to the cathode of the Schottky diode SD1 in the feedback circuit, and the other end is connected to the collector of the transistor T6 to store energy and provide a delay response in the case of overcurrent.

5. The overcurrent protection circuit for a high-side switch according to claim 2, wherein: The high-side switch T1 uses a PMOS transistor, and the MOS transistor T4 is an NMOS transistor.

6. The overcurrent protection circuit for a high-side switch according to claim 3, wherein: The transistor T3 is a PNP-type transistor, and the transistor T6 is an NPN-type transistor.

Images