Use two batteries to generate +5V and +12V circuits

Portable electronic products powered by batteries generally use low power supply voltages, which can reduce the number of batteries and reduce product size and weight. Therefore, 3~5V is generally used as the operating voltage to ensure the stability and accuracy of circuit operation. A regulated power supply is required. If the circuit uses a 5V working voltage but requires a higher working voltage, this often puts the designer in a dilemma. This article introduces a circuit composed of two boost modules that can solve this problem and only needs two batteries for power supply. The circuit is characterized by few peripheral components, small size, light weight, stable output of +5V and +12V, and meets the requirements of portable electronic products. The +5V power supply can output 60mA, and the maximum output current of the +12V power supply is 5mA. The circuit is shown in the picture above. It consists of AH805 boost module and FP106 boost module. AH805 is a boost module with an input of 1.2~3V and an output of 5V. It can output 100mA current when powered by 3V. FP106 is a chip-type boost module with an input of 4~6V, a fixed output voltage of 29±1V, and an output current of up to 40mA. Both AH805 and FP106 are level-controlled power-off control terminals. The 3V voltage output by two 1.5V alkaline batteries is input to the AH805. The AH805 outputs a +5V voltage. One of the channels is used as a 5V output, and the other channel is input to the FP106 to generate a voltage of 28~30V. After being stabilized by the voltage regulator tube, it outputs a +12V voltage. As can be seen from the figure, as long as the voltage stabilization value of the voltage regulator tube is changed, different output voltages can be obtained, and the use is very flexible. The ⑤ pin of FP106 is the control power off terminal. When the power is turned off, the power consumption is almost zero. When the ⑤ pin is added to the high level >2.5V, the power supply is turned on; when the ⑤ pin is added to the low level <0.4V , the power is turned off. It can be controlled by circuit or manually. If control is not required, connect pin ⑤ to pin ⑧.