Analysis of Circuit Diagram of UPS Power Supply for Single Chip Microcomputer

Single chip microcomputer STM32L151CCU6

description:

The high voltage and small current power supply is suitable for the alarm protection system, and its discharge current is only on the order of microamperes. The circuit is as shown in the figure.

UPS power supply circuit for single chip microcomputer

The working principle of the circuit: the transistor VT, the step-up transformer T and C2, C3 and other components constitute a transformer-coupled multivibrator. As shown in the figure, the oscillation frequency is about 10 kHz. A pulse voltage of a peak-to-peak voltage of 24 V is applied across the primary winding L1 of the transformer T, and is boosted by the transformer T to generate a high voltage of about 70 OV at both ends of the secondary winding L3. VD6~VD11 and C4~C9 form a voltage doubler rectification (actually measured more than 3 times) circuit, which generates a pulsating DC high voltage of about 2O2kV between the output terminal and ground.

One of the key components of the circuit is the step-up transformer T, and the number of turns of the three windings (L1 to L3) is as shown in the figure. Among them, the line of L1 and L2 is φ0.18mm, and the diameter of L3 is φ0.07mm. When winding and assembling, attention should be paid to the connection of the same name of L1 and L2, otherwise the circuit cannot start. The diodes, transistors and capacitors in the circuit should be careful not to be too low. In addition, it should be noted that there should be a certain distance between the high-voltage components, and keep the dust and moisture resistance of the whole device well. If you need to increase the output voltage, increase the power supply voltage, but you must pay attention to the high voltage of the relevant components can not exceed its rated value.