Abstract:

A new low-cost isolated flyback switch Li-battery power supply is designed for battery-powered medical instruments with high voltage and isolated function.The chip with current type of pulse width modulation (PWM) UC3845 and a feedback circuit are used to realize the isolate and dual-output function.The input of the designed power is 10~14 V and the dual-output are +35 V and -35 V.The consumed power is 14 W with an efficiency of 75%.The size of the module is 65 mm×40 mm.The simulation and experiment results validate that the power supply module can realize the ±35 V power isolated supply.

Key words: flyback;switching power supply;current type pulse width modulation;feedback circuit