Design of Electronic Circuits for DC Low Voltage Regulated Power Supply
Release time:
2019-07-29
The design of electronic circuits for DC low-voltage regulated power supplies is widely used in power management. Therefore, today I will provide a simple analysis of circuit diagrams for this type of design, hoping to assist readers in designing such applications.
The design of low-voltage DC regulated power supply electronic circuits is widely used in power management. Therefore, today we will provide a simple analysis of the circuit diagram for this type of design, hoping to assist readers in designing such applications.
The switch power supply part consists of VD1-VD4, R1, C1, and C2, forming a rectification and filtering circuit. NE555 and components such as R2, R3, C4, and VD6 form a multi-vibrating oscillation circuit with a frequency of about 20KHz. R4, C3, and VD5 form a step-down voltage regulation circuit, providing a 12V working power supply for NE555. The high-power transistor VT1 and transformer T constitute the switching circuit. The working state of VT1 is controlled by pin 3 of NE555, and the conduction time is determined by the pulse width, which can be adjusted by changing R3. When the pulse width increases, the output voltage rises; when the pulse width decreases, the output voltage drops. VT2, along with R8, R9, and C6, forms an overcurrent protection circuit. When the load is too heavy or a short circuit occurs, VT2 conducts, forcing NE555 to reset and stop oscillating, thus protecting VT1 from damage. C7 and R10 form a protection network to prevent the c-e junction of VT1 from being punctured by instantaneous pulses. The two secondary windings output 20V and 12V after rectification and filtering. To simplify the design, the switch power supply is designed not to have automatic voltage regulation; its function is similar to that of a transformer, achieving lightweight isolation and step-down effect, while the voltage regulation function is realized by the subsequent voltage regulation circuit. The 12V DC voltage is regulated by 7805 to output +5V voltage; the 20V DC voltage is sent to the adjustable voltage regulation circuit.
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