CN214799289U - Power-off discharge circuit of power supply - Google Patents

Abstract

The embodiment of the utility model discloses shutdown discharge circuit of power, including MOS pipe Q1, MOS pipe Q2, stabilivolt Z1, electric capacity C2, resistance R1, resistance R2, diode D1, diode D1 negative pole and electric capacity C2 one end are connected to MOS pipe Q1's G utmost point; the D poles of the MOS transistor Q1 and the MOS transistor Q2 are respectively connected with the anode of an external power supply through a resistor R2 and a resistor R1; the negative electrode of the voltage-stabilizing tube Z1 is connected with the G electrode of the MOS tube Q2 and the D electrode of the MOS tube Q1; the anode of the voltage regulator tube Z1, the other end of the capacitor C2, and the S poles of the MOS tube Q1 and the MOS tube Q2 are grounded. The utility model discloses a when two MOS pipes and one set of simple circuit realize shutting down, release fast to remaining electric charge on the big electric capacity, and the during operation can not increase the consumption of product normally, the utility model discloses a circuit structure is simple, and the space is little, and is with low costs.

Description

Power-off discharge circuit of power supply

Technical Field

The utility model relates to a switching power supply technical field especially relates to a shutdown discharge circuit of power.

Background

In a switching power supply product, a primary side or a secondary side of a power supply has a large-capacity electrolytic capacitor for filtering, storing energy and the like. When the switch power supply product is shut down in no-load mode, the charges on the capacitors are not discharged by the load, and the voltage at the two ends of the capacitors can be maintained for a long time. Such voltages pose certain safety hazards in the production and consumer applications of the product.

In the prior art application, the method for solving the problem is as follows: the two ends of the capacitor needing to be discharged are connected with a discharge resistor in parallel, and the disadvantage is that the power consumption of the product is increased.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a technical problem that will solve lies in, provides a shutdown discharge circuit of power to realize on the basis that does not increase the product consumption, release fast remaining electric charge on the big electric capacity when shutting down.

In order to solve the technical problem, an embodiment of the present invention provides a shutdown discharge circuit for a power supply, including a MOS transistor Q1, a MOS transistor Q2, a voltage regulator tube Z1, a capacitor C2, a resistor R1, a resistor R2, a diode D1, a G electrode of the MOS transistor Q1 is connected with a cathode of the diode D1 and one end of the capacitor C2; the D poles of the MOS transistor Q1 and the MOS transistor Q2 are respectively connected with the anode of an external power supply through a resistor R2 and a resistor R1; the negative electrode of the voltage-stabilizing tube Z1 is connected with the G electrode of the MOS tube Q2 and the D electrode of the MOS tube Q1; the anode of the voltage regulator tube Z1, the other end of the capacitor C2, and the S poles of the MOS tube Q1 and the MOS tube Q2 are grounded.

Further, the MOS transistor Q1 and the MOS transistor Q2 are N-MOS transistors.

The utility model has the advantages that: the utility model discloses a when two MOS pipes and one set of simple circuit realize shutting down, release fast to remaining electric charge on the big electric capacity, and the during operation can not increase the consumption of product normally, the utility model discloses a circuit structure is simple, and the space is little, and is with low costs.

Drawings

Fig. 1 is a circuit diagram of a shutdown discharge circuit of a power supply according to an embodiment of the present invention.

Detailed Description

It should be noted that, in the present application, the embodiments and features of the embodiments may be combined with each other without conflict, and the present invention is further described in detail with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1, the shutdown discharge circuit of the power supply of the embodiment of the present invention includes a MOS transistor Q1, a MOS transistor Q2, a regulator tube Z1, a capacitor C2, a resistor R1, a resistor R2, and a diode D1.

The G pole of the MOS transistor Q1 is connected with the cathode of the diode D1 and one end of the capacitor C2; the D poles of the MOS transistor Q1 and the MOS transistor Q2 are respectively connected with the anode of an external power supply through a resistor R2 and a resistor R1; the negative electrode of the voltage-stabilizing tube Z1 is connected with the G electrode of the MOS tube Q2 and the D electrode of the MOS tube Q1; the anode of the voltage regulator tube Z1, the other end of the capacitor C2, and the S-poles of the MOS transistor Q1 and the MOS transistor Q2 are grounded (i.e., the negative pole of the power supply).

In one embodiment, the MOS transistors Q1 and Q2 are N-MOS transistors.

Referring to fig. 1, C1 represents a large capacitance in the power supply. The utility model discloses Q1, Q2, Z1, R1, R2, C2, D1 of embodiment constitute discharge circuit, give C1 and discharge. The anode (i.e., point a in fig. 1) of the diode D1 is connected to the primary side PWM driving signal or the secondary side synchronous rectification driving signal (depending on whether the circuit discharges the primary side capacitor or the secondary side capacitor).

The working principle of the utility model is as follows:

when the power supply normally works, a driving signal is provided at a point A, the signal is rectified and filtered by D1 and C2 to provide a voltage for a G pole of Q1, when the voltage is higher than a threshold voltage of Q1, Q1 is conducted, and Q2G pole voltage = VCC + multiplied (Q1 conducting internal resistance/Q1 conducting internal resistance + R2). Q1 selects N-MOS with small on-resistance, and when Q1 is on, the G voltage of Q2 is lower than the on-threshold voltage, and then Q2 is cut off. The negative terminals of the discharge resistor R1 and the capacitor C1 are in an open circuit state, so that the capacitor cannot be discharged, and the power consumption cannot be increased when the power supply product works normally.

When the power supply product is shut down, because the point A does not have a driving signal, the G pole of the Q1 is cut off without voltage bias voltage, the voltage of the positive end of the large capacitor C1 charges the Q2G pole through the current-limiting resistor R2, and when the voltage of the Q2G pole is higher than the threshold voltage of the Q2, the Q2 is conducted (the Z1 has an amplitude limiting function and prevents the voltage of the Q2G pole from being damaged due to overhigh voltage). The voltage across the large capacitor C1 is bled off through R1, Q2 to the negative terminal.

When the machine is shut down, the utility model discloses remaining electric charge is released fast on big electric capacity, guarantees product and operation and use personnel's safety, and the consumption of product can not increase in normal during operation.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (2)

1. A power-off discharge circuit of a power supply is characterized by comprising an MOS tube Q1, an MOS tube Q2, a voltage regulator tube Z1, a capacitor C2, a resistor R1, a resistor R2 and a diode D1, wherein the G pole of the MOS tube Q1 is connected with the negative pole of the diode D1 and one end of the capacitor C2; the D poles of the MOS transistor Q1 and the MOS transistor Q2 are respectively connected with the anode of an external power supply through a resistor R2 and a resistor R1; the negative electrode of the voltage-stabilizing tube Z1 is connected with the G electrode of the MOS tube Q2 and the D electrode of the MOS tube Q1; the anode of the voltage regulator tube Z1, the other end of the capacitor C2, and the S poles of the MOS tube Q1 and the MOS tube Q2 are grounded.

2. The power-off discharge circuit of claim 1, wherein the transistors Q1 and Q2 are N-MOS transistors.