High-reliability circuit board power-on and power-off control circuit
Through the control circuit composed of P-channel MOS tube and transistor, soft start on the circuit board and quick release of charge after power failure is achieved, solving the problem of system instability and slow voltage drop caused by instant power supply during power outage during power outage of the circuit board, and improving the reliability and safety of the circuit board.
Patent Information
- Application Number
- CN202422373653.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-28
- Publication Date
- 2025-07-29
- Estimated Expiration
- 2034-09-28
AI Technical Summary
During power-on and power-down, existing circuit boards have problems such as instant power-on power-up, resulting in system instability, component damage and circuit board failure to reset normally, especially when the load capacitance is present, the voltage drops slowly and causes equipment abnormality.
The control circuit consisting of P-channel MOS tube and NPN/PNP transistor is adopted to control the MOS tube on and off through the power switch to achieve power-on soft start, and the power-on time is adjusted by capacitance and resistor, and the power-off residual power is quickly released through the PNP transistor to ensure that the voltage is quickly returned to zero.
It realizes smooth control of the power-on process and rapid charge release in the power-off process, improves the reliability of the circuit board, avoids equipment abnormalities and component damage, and ensures the safety of the circuit board.
Smart Images
Figure CN223168226U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the field of circuit board reliability design, and more specifically, relates to a power-on and power-off control circuit for a high-reliability circuit board. Background Technique
[0002] It is found in daily work that the power-on and power-off of the internal circuit power supply of most previous devices are only controlled by switches, which has caused many problems. For example, when powering on a certain board in a multi-board device, the power supply powers on too quickly and urgently, and the load is suddenly powered on, which will suddenly demand a very large current from the power supply module, causing the power supply module to be overloaded and powered off, resulting in system instability, affecting the normal operation of other boards, and even causing damage to components. Also, when the power switch is disconnected, if there is a large capacitor in the load circuit, the voltage on the load circuit will drop slowly. If the power switch is re-closed in this case, since the circuit board has not been completely powered off, some chips in the circuit board will not be able to perform normal power-on reset and startup, causing the device to work abnormally or even not work. If a circuit can be designed to control the power-on and power-off processes to make the power-on process smoother and the voltage after power-off quickly return to zero, this problem can be solved, protecting the safety of the circuit board and avoiding property losses. Content of the Utility Model
[0003] The purpose of the utility model is to overcome the deficiencies in the prior art and provide a power-on and power-off control circuit for a high-reliability circuit board, which can realize soft start during power-on and quickly release excess charge during power-off, thereby improving the reliability of the circuit board. The utility model makes the power-on process smoother and the voltage after power-off quickly return to zero, protecting the safety of the circuit board and avoiding property losses.
[0004] The purpose of the utility model is achieved through the following technical solutions.
[0005] The power-on and power-off control circuit for the high-reliability circuit board of the utility model includes a power switch connected between the power supply and the load circuit. One end of the power switch is connected to the power supply as the power input end, and the other end is divided into four paths: the first path is connected to the base of the second triode, the second path is connected to the base of the first triode through the fourth resistor, the third path is connected to the collector of the first triode through the first resistor, and the fourth path is connected to the source of the MOS transistor; the base of the second triode is also grounded through the sixth resistor, the collector is grounded through the seventh resistor, and the emitter is connected to the drain of the MOS transistor; the base of the first triode is also grounded through the fifth resistor, the emitter is grounded, and the collector is connected to the gate of the MOS transistor through the third resistor; a capacitor is connected between the source and the gate of the MOS transistor, and the drain of the MOS transistor is connected to the subsequent load circuit as the power output end.
[0006] Further, the MOS transistor is a P-channel MOS transistor.
[0007] Further, the first triode is an NPN type triode, and the second triode is a PNP type triode.
[0008] Compared with the prior art, the beneficial effects brought by the technical solution of the present utility model are as follows:
[0009] In the present utility model, the on-off of the power switch, that is, the presence or absence of the power supply voltage used, is used as a control signal. The power-on process is controlled by controlling the on-off of the MOS transistor, and the power-off process is controlled by controlling the on-off of the first triode and the second triode. Among them, a capacitor is added between the gate G and the source S of the MOS transistor to achieve a soft start during power-on. By adjusting the values of the capacitor and resistor, the soft start time during power-on can be adjusted. By adjusting the resistance value of the seventh resistor between the collector c of the second triode and the ground GND, the discharge speed during the power-off process can be adjusted. Description of the Drawings
[0010] Figure 1 is a schematic diagram of the power-on and power-off control circuit of the high-reliability circuit board of the present utility model.
[0011] Reference numerals: Q1 - MOS transistor, Q2 - first triode, Q3 - second triode, S1 - power switch, R1 - first resistor, R2 - load, R3 - third resistor, R4 - fourth resistor, R5 - fifth resistor, R6 - sixth resistor, R7 - seventh resistor, C1 - capacitor, C2 - load capacitor, VCC_IN - power input terminal, VCC_OUT - power output terminal. Detailed Embodiment
[0012] In order to make the above objects, features, and advantages of the present utility model more obvious and understandable, the following detailed description of the specific embodiments of the present utility model will be given with reference to the accompanying drawings.
[0013] As Figure 1As shown in the figure, the power-on and power-off control circuit of the high-reliability circuit board of the present utility model includes a power switch S1 connected between a power supply and a load circuit. One end of the power switch S1 serves as a power input terminal VCC_IN for connecting to the power supply, and the other end is divided into four paths: the first path is directly connected to the base b of the second triode Q3, the second path is connected to the base b of the first triode Q2 through the fourth resistor R4, the third path is connected to the collector c of the first triode Q2 through the first resistor R1, and the fourth path is connected to the source S of the MOS transistor Q1. The base b of the second triode Q3 is also grounded to GND through the sixth resistor R6, the collector c is grounded to GND through the seventh resistor R7, and the emitter is connected to the drain D of the MOS transistor Q1. The base b of the first triode Q2 is also grounded to GND through the fifth resistor R5, the emitter e is grounded to GND, and the collector c is connected to the gate G of the MOS transistor Q1 through the third resistor R3. A capacitor C1 is connected between the source S and the gate G of the MOS transistor Q1. The drain D of the MOS transistor Q1 serves as a power output terminal VCC_OUT for connecting to a subsequent load circuit, such as a load circuit composed of a load capacitor C2 and a load R2, but is not limited to this load circuit.
[0014] In the above control circuit, preferably, the MOS transistor Q1 can be a P-channel MOS transistor. For example, CJ3401 of Jiangsu Changjing can be selected, with a breakdown voltage of 30V and a continuous drain current of 4.2A, which is used to control the power on and off during the power-on process. Other P-channel MOS transistors that meet the power-on voltage and current of the circuit board can also be selected for replacement.
[0015] In the above control circuit, preferably, the first triode Q2 can be an NPN-type triode. For example, S8050 of Jiangsu Changjing can be selected, which conducts when the input is high level and has a collector current (Ic) of 500mA. It is used as a switch, and any NPN-type triode can be replaced.
[0016] In the above control circuit, preferably, the second triode Q3 can be a PNP-type triode. For example, S8550 of Jiangsu Changjing can be selected, which conducts when the input is low level and has a collector current (Ic) of 500mA. It is used to release the remaining power after power-off. When selecting, only the current needs to meet the discharge speed of its own circuit board.
[0017] In the above control circuit, preferably, the capacitor C1 can be a 0.47uF ceramic capacitor, which is used to achieve soft start during power-on. Increasing the capacitance value can extend the soft start time, and conversely, decreasing the capacitance value can shorten the soft start time.
[0018] The working process of the power-on and power-off control circuit of the high-reliability circuit board of the present utility model is as follows:
[0019] Power-on process: When the power switch S1 is closed, the base b of the second triode Q3 is at a high level, and the second triode Q3 is not conducting. The base b of the first triode Q2 is at a high level, and the first triode Q2 is conducting. The capacitor C1 starts to charge, and the voltage V between the gate G and the source S of the MOS transistor Q1 GS slowly decreases to the -VCC_IN voltage value, causing the MOS transistor Q1 to slowly turn on, realizing the soft start of the power-on process. By adjusting the values of the third resistor R3 and the capacitor C1, the turn-on speed of the MOS transistor Q1 can be adjusted to control the soft start time of the circuit board.
[0020] Power-off process: When the power switch S1 is disconnected, the base b of the first triode Q2 is at a low level, and the first triode Q2 is not conducting. The capacitor C1 starts to discharge, and the voltage V between the gate G and the source S of the MOS transistor Q1 GS slowly rises to 0V, causing the MOS transistor Q1 to slowly turn off and return to its initial state. Since the power switch S1 is disconnected and there is no input power, the slow turn-off of the MOS transistor Q1 will not affect the load circuit. At the same time, the base b of the second triode Q3 is also at a low level, and the second triode Q3 is conducting. The load capacitor C2 (referring to the large capacitor in the load circuit) starts to discharge through the seventh resistor R7, quickly discharging the voltage at the power output terminal VCC_OUT to zero, realizing the rapid release of residual electricity during the power-off process. By adjusting the resistance value of the seventh resistor R7, the speed of residual electricity release can be adjusted, but it should be noted that the power of the resistor and the maximum current of the second triode Q3 should meet the requirements to prevent component damage.
[0021] In addition, based on the above control circuit, in the present utility model, the base b of the first triode Q2 can be directly connected to the CPU or the single-chip microcomputer through the fourth resistor R4, without being connected to the power switch S1. The base b of the second triode Q3 is directly connected to the CPU or the single-chip microcomputer, without being connected to the power switch S1. After such modification, it can be directly controlled by the program, and the power-on and power-off processes can be controlled more flexibly.
[0022] Although the functions and working processes of the present utility model are described above in conjunction with the accompanying drawings, the present utility model is not limited to the above specific functions and working processes. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present utility model, those of ordinary skill in the art can also make many forms without departing from the purpose of the present utility model and the scope protected by the claims. These all fall within the protection scope of the present utility model.
Claims
1. A power-on and power-off control circuit for a high-reliability circuit board, including a power switch (S1) connected between a power supply and a load circuit, characterized in that, One end of the power switch (S1) is connected to a power supply as a power input terminal (VCC_IN), and the other end is divided into four paths: the first path is connected to the base of the second triode (Q3), the second path is connected to the base of the first triode (Q2) through the fourth resistor (R4), the third path is connected to the collector of the first triode (Q2) through the first resistor (R1), and the fourth path is connected to the source of the MOS transistor (Q1); the base of the second triode (Q3) is also grounded (GND) through the sixth resistor (R6), the collector is grounded (GND) through the seventh resistor (R7), and the emitter is connected to the drain of the MOS transistor (Q1); the base of the first triode (Q2) is also grounded (GND) through the fifth resistor (R5), the emitter is grounded (GND), and the collector is connected to the gate of the MOS transistor (Q1) through the third resistor (R3); a capacitor (C1) is connected between the source and the gate of the MOS transistor (Q1), and the drain of the MOS transistor (Q1) is connected to a subsequent load circuit as a power output terminal (VCC_OUT).
2. The high-reliability circuit board power-on and power-off control circuit according to claim 1, wherein The MOS transistor (Q1) is a P-channel MOS transistor.
3. The high-reliability circuit board power-on and power-off control circuit according to claim 1, characterized in that, The first triode (Q2) is an NPN-type triode, and the second triode (Q3) is a PNP-type triode.