Switching Mode Power Supply Chip Design Based On PSR Flyback With Constant Current And Constant Voltage

Couplings with conventional secondary-side flyback converters can achieve precise voltage and current control,but there are more components,larger board space,high cost and low reliability.The flyback converter with primary side regulation working at DCM mode with primary side current control.It also eliminating the secondary sampling circuit and the need for the TL431 oroptocoupler,reducing component number and the complexity of the overall circuit,making the chip system more efficient and optimized.Study about the working style of switching power supply chip,and analyze the application of flyback converter structure topology and primary side feedback(PSR)technology.After analyse the system requirements detaily,according to the design objectives to complete the system as a whole circuit design and function.The power supply chip designed in this paper based on the flyback converter topology,using primary side feedback(PSR)technology to achieve constant current and constant voltage output.Constant current output using PFM control mode,constant voltage output using PFM and PWM control mode.The chip contains constant current PFM control system,constant voltage PFM control system,constant voltage PWM control system,sample and hold circuit,undervoltage lockout,leading edge blanking,bandgap reference Bandgap,oscillator,cable voltage compensation and other modules.Use Cadence's virtuoso software to simulate the circuit.Simulation results showed that the chip can achieve a good constant current and constant voltage output,the circuit of the various sub-modules also have reached the performance indicators.Constant output current is 364.71 m A,constant output voltage is 7.486 V,the error is not more than 1%,power switch duty cycle is from 0.03 to 0.25,the results all achieve the goal.