Self-switching voltage stabilizing circuit of power supply

Abstract

The invention relates to a self-switching voltage stabilizing circuit of a power supply. The self-switching voltage stabilizing circuit comprises a voltage stabilizing unit part and a power supply switching unit, wherein an external power supply voltage input end is connected with the voltage stabilizing unit part, the voltage stabilizing unit part is connected with a power supply voltage output end through the power supply switching unit part, and the power supply switching unit part is also connected with a backup power supply positive input end. The self-switching voltage stabilizing circuit has advantage of being designed by adopting split elements and devices, so that the design is relatively flexible, an appropriate MOSFET (metal oxide semiconductor field effect transistor) is selected, a voltage stabilizing circuit with high input voltage can be designed, for example a voltage stabilizing circuit with the input voltage of 8V to 60V can be designed; meanwhile, the MOSFET is relatively high in efficiency, and the voltage stabilizing circuit with relatively large output current under the same size can be designed.

Description

technical field [0001] The invention relates to a voltage stabilizing circuit supporting automatic switching of external direct current and backup battery supply. Background technique [0002] In the design of low-power instruments, 3.6V Li-SOCL2 disposable lithium batteries are often used as backup power for RTC, MCU or LCD and other low-power circuits after power failure. In the circuit design, it is necessary to design a switching circuit for the power supply selection after the external DC power supply is powered off or powered on. The conventional method is as follows: figure 1 As shown, the low-dropout linear regulator U1 and the diode switching method are used. The switching circuit adopts the diode isolation method. It must ensure that the external DC power supply voltage is greater than the battery voltage to ensure correct switching. [0003] When the voltage stabilizing unit outputs 5V, the circuit can ensure accurate switching. However, as integrated circuits a...

AI Technical Summary

Problems solved by technology

[0005] 1) Due to the voltage drop of the diode tube, the utilization capacity of the battery becomes smaller;

[0006] 2) When the load current of the diode changes, the change of its tube voltage drop causes the output voltage to be unstable, the light load voltage is too large, and the heavy load voltage is too low;

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