Power supply system and switch circuit, switch method of main power source and backup battery

Abstract

This invention discloses a power supply system, a switch circuit and a method for its master supply and a standby battery, in which, the switch circuit includes a P-MOS field effect transistor, a voltage sample circuit and a switch circuit, when the sample voltage of the sample end reaches to a preset value or over it, the switch circuit is turned on, its voltage output end outputs control signals to conduct the P-MOS field effect transistor and the DC master output end of the master supply conducts the bus end, when the voltage of the sample end is lower than a preset value, the switch circuit is turned off to stop the field effect transistor and the standby cell supplies to the bus, since the conduction resistance of the P-MOS field effect transistor is low, its voltage drop can be very small and the power loss of the switch circuit is reduced greatly.

Description

【Technical field】 [0001] The invention relates to a power circuit. 【Background technique】 [0002] In the power supply or power supply system with battery backup, when there is a power adapter or other DC power supply, the DC main output of the main power supply (including AC to DC conversion or DC to DC conversion output) is required to supply power to the system, and the DC The main output charges the battery. When the DC main output power supply is interrupted, the battery backup output needs to continue to supply power to the system without interruption. For the system, it is often necessary to realize the uninterrupted switching between the DC main input and the battery input, as well as the isolation of the DC main input and the battery backup input, so as to prevent the backfeeding of the battery voltage to the DC main output. [0003] At present, the main power supply and backup battery switching technologies mainly include: [0004] 1) Diode isolation method: In o...

AI Technical Summary

Problems solved by technology

[0007] The first scheme is the most widely used scheme, the circuit is simple, but the power supply efficiency is too low

[0008] In the second scheme, when the system needs to use two sets of backup batteries for isolated power supply, it is necessary to ensure the independence of the batteries to prevent the charging and discharging between the batteries due to direct parallel connection between the batteries. Diode isolation is required between the batteries, so that MOS field effect transistors cannot be used to reduce losses, because MOS field effect transistors have bidirectional conduction characteristics after they are turned on, so the second solution is not suitable for places where more than two sets of batteries supply power at the same time

In addition, in some places that are mainly powered by DC output, it is hoped to improve the power supply efficiency of DC main output. At this time, the second solution cannot solve the efficiency problem of DC main output power supply, so the second solution is limited in many aspects.

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