TWI428733B - Control circuit for switch power supply - Google Patents

Description

Switching power supply control circuit

The invention relates to a switching power supply control circuit.

Switch power supply (SPS) is widely used in computers, servers, workstations, etc. After the computer is turned off, the internal switching power supply control circuit will still output a 5V standby standby voltage to the computer motherboard. It is used by the power monitoring unit of the computer motherboard, the network communication interface, the system clock chip, etc., in preparation for starting the power of the computer. However, if the computer is not used for a long time after the software is turned off, the 5V standby standby voltage will have power loss and energy loss.

In view of the above, it is necessary to provide a switching power supply control circuit that can effectively reduce the energy loss of the switching power supply.

A switching power supply control circuit includes a power input interface for connecting an external power source, a power output interface for connecting a power supply, an AC/DC converter, a relay, a relay drive circuit, and a microprocessor The AC/DC converter is configured to convert an AC voltage from the power input interface into a DC voltage and provide the relay, a relay driving circuit and a microprocessor, wherein an internal switch of the relay is connected to the power input interface and the power output Between the interfaces, when the microprocessor receives the shutdown signal or the power-on signal of the computer motherboard, a control signal is outputted to the relay driving circuit to control the opening and closing of the internal switch of the relay.

Compared with the prior art, when the computer motherboard software is turned off, the switching power supply control circuit receives the shutdown signal of the computer motherboard through the microprocessor, and controls the relay driving circuit to drive the relay to open the internal switch of the relay. In turn, the connection between the external power source and the power supply is interrupted, so that power is saved to a certain extent and the cost is reduced.

Referring to FIG. 1 , a preferred embodiment of the switching power supply control circuit 100 of the present invention is applied to a computer system. The switching power supply control circuit 100 includes a power input interface 10 , an AC/DC converter 20 , a relay 30 , and a relay . The driving circuit 40, a microprocessor 50 and a power output interface 60 are provided.

The power input interface 10 is used for connecting an external power source (such as a 220V AC power source), and the external power source is supplied to a power supply 70 through the power output interface 60, and the power conversion circuit in the power supply 70 receives the power supply circuit 70. The power signal (such as 5V system power supply 5V_sys, 5V standby power supply 5Vsb, etc.) required for converting the external power signal into a computer motherboard 80 is provided to the computer motherboard 80.

The AC/DC converter 20 receives the AC voltage of the external power source through the power input interface 10 and converts it into a DC voltage (eg, 5V) for operation of the relay 30, the relay drive circuit 40, and the microprocessor 50. The switch K of the relay 30 is connected to the live line L on the power input interface 10. The microprocessor 50 is connected to the power-on signal pin Power-on, the power supply signal pin Power supply-on, the power-on enable pin PO-enable and the USB connector 81 of the computer motherboard 80. The microprocessor 50 The standby power output pin 5V_sb of the power supply 70 and the relay drive circuit 40 are also connected.

When the operator turns on the computer system, the power-on signal pin Power-on transmits a power-on signal to the microprocessor 50, and the microprocessor 50 outputs a control signal to control the relay driving circuit 40 to drive the relay 30. The switch K is closed, and the external power source supplies power to the power supply 70 through the power input interface 10 and the power output interface 60. The standby power output pin 5V_sb of the power supply 70 and the system power output pin 5V_sys power the computer motherboard 80 and output a 5V voltage signal to the microprocessor 50 through the standby power output pin 5V_sb. The computer motherboard 80 outputs a feedback signal to the microprocessor 50 through the power supply signal pin Power supply-on to indicate that the power supply is normal. After receiving the feedback signal and the 5V voltage signal output by the power supply 70, the microprocessor 50 outputs an activation signal to the power-on enable pin PO-enable of the computer motherboard 80 to make the computer motherboard 80 boot.

When the operator turns off the computer system, the USB connector 81 receives the shutdown signal of the computer motherboard 80 and outputs a shutdown signal to the microprocessor 50, and the microprocessor 50 outputs a control signal to control the The relay drive circuit 40 drives the relay 30 to open the switch K, thereby disconnecting the external power source from the power supply 70, so that the computer motherboard 80 has no power loss in the off state.

Referring to FIG. 2 together, the relay driving circuit 40 is a transistor Q1. In other embodiments, the relay driving circuit 40 may also be other switching circuits according to design requirements. The relay drive circuit 40 and the AC/DC converter 20 are well-known technologies in the prior art and will not be described in detail. The neutral line N and the ground line G of the power input interface 10 are both connected to pins corresponding to the power output interface 60.

One end of the coil J of the relay 30 is connected to the AC/DC converter 20 through a resistor to generate a 5V DC voltage and is grounded through a capacitor, and the other end is connected to the collector of the transistor Q1. The emitter of the transistor Q1 is grounded and the base is connected to the pin 16 of the microprocessor 50. The microprocessor 50 is an EM78612A type wafer, and its pin 1 is connected to the standby power output pin 5V_sb of the power supply 70. The microprocessor 50 is only used when the power output interface 60 supplies power to the power supply 70. There is a 5V DC voltage input on pin 1 to detect the operation of the power supply 70; pin 2 is connected to the power enable pin PO-enable of the computer motherboard 80, only when the power supply 70 When the computer motherboard 80 is powered normally, the pin 2 of the microprocessor 50 outputs a start signal to the boot enable pin PO-enable to enable the computer motherboard 80 to be turned on; pins 3 and 4 are respectively connected to the computer. The power-on signal of the motherboard 80 is powered by the power-on and the power supply signal pin Power supply-on to control the output of the pin 2 of the microprocessor 50; the pins 5 and 6 are grounded; the pin 7 is connected to a 3.3V. The DC power supply is grounded through a capacitor C1; pins 8 and 9 are grounded through a capacitor C2 and C3 respectively; pin 10 is connected to a 5V DC power supply; pins 11 and 13 are connected to a 3.3V DC power supply; pin 12 is connected to the USB connector 81; pins 14 and 15 are left floating.

When the power input interface 10 of the switching power supply control circuit 100 is connected to an external power source, the power output interface 60 of the switching power supply control circuit 100 is connected to the corresponding power interface 71 of the power supply 70, and the computer system is turned on. The pin 16 of the processor 50 outputs a high level signal to control the transistor Q1 to be turned on. At this time, the voltage difference between the coil L of the relay 30 causes the switch K to be closed, so that the external power source passes through the power input interface 10 and The power output interface 60 supplies power to the power supply 70. Further, the power supply 70 supplies power to the computer motherboard 80. As described above for the circuit in FIG. 1, when the pin 2 of the microprocessor 50 outputs a start signal to the boot enable pin PO-enable, the computer motherboard 80 is turned on.

When the user turns off the computer system, the shutdown signal pin (not shown) of the computer motherboard 80 sends a shutdown signal to the microprocessor 50 through the USB connector 81, so that the microprocessor 50 The pin 16 outputs a low level signal to control the transistor Q1 to be turned off. At this time, the voltages of the coils L of the relay 30 are equal, so that the switch K is turned off, that is, the external power source and the power supply 70 are disconnected. The connection between the external circuit and the power supply 70 is interrupted, that is, no voltage is supplied to the computer motherboard 80, and the standby voltage is also interrupted, thereby saving power to a certain extent and reducing The cost.

In this embodiment, the control signal is low when the power is off, and is high when the power is turned on. In other embodiments, the correspondence between the form of the control signal and the state of the power on and off can be according to the relay. The drive circuit 40 is changed.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be covered by the following claims.

10‧‧‧Power input interface
20‧‧‧AC/DC converter
30‧‧‧Relay
40‧‧‧Relay drive circuit
50‧‧‧Microprocessor
60‧‧‧Power output interface
70‧‧‧Power supply
80‧‧‧Computer motherboard
71‧‧‧Power interface
81‧‧‧USB connector
100‧‧‧Switching power supply control circuit
K‧‧ switch
J‧‧‧ coil
C1-C3‧‧‧ capacitor
Q1‧‧‧Optoelectronics

1 is a block diagram showing a preferred embodiment of a switching power supply control circuit of the present invention connected to a power supply and a computer motherboard.

Figure 2 is a circuit diagram of Figure 1.

10‧‧‧Power input interface

20‧‧‧AC/DC converter

30‧‧‧Relay

40‧‧‧Relay drive circuit

50‧‧‧Microprocessor

60‧‧‧Power output interface

70‧‧‧Power supply

80‧‧‧Computer motherboard

71‧‧‧Power interface

81‧‧‧USB connector

100‧‧‧Switching power supply control circuit

K‧‧ switch

Claims (4)

A switching power supply control circuit includes a power input interface for connecting an external power source, a power output interface for connecting a power supply, an AC/DC converter, a relay, a relay drive circuit, and a microprocessor The AC/DC converter is configured to convert an AC voltage from the power input interface into a DC voltage and provide the relay, a relay driving circuit and a microprocessor, wherein an internal switch of the relay is connected to the power input interface and the power output Between the interfaces, when the microprocessor receives the shutdown signal or the power-on signal of the computer motherboard, a control signal is outputted to the relay driving circuit to control the opening and closing of the internal switch of the relay. The switching power supply control circuit of claim 1, wherein the relay driving circuit comprises a transistor, the internal coil of the relay is connected to the AC/DC converter at one end, and the other end is connected to the collector of the transistor. The emitter of the transistor is grounded and the base is coupled to the microprocessor to receive the control signal. The switching power supply control circuit of claim 2, wherein the microprocessor is connected to a power-on signal pin and a USB connector of the computer motherboard, and the power-on signal of the computer motherboard is powered by the computer motherboard The power-on signal pin is transmitted to the microprocessor; the shutdown signal of the computer motherboard is transmitted to the microprocessor through the USB connector. The switching power supply control circuit of claim 3, wherein the microprocessor is further connected to a power supply signal pin of the computer motherboard, a boot enable pin, and a standby power output pin of a power supply.