EMI Filter and rectifier circuit EMI Filter Rectifier

EMI Filter and rectifier circuit EMI Filter Rectifier circuit

Power stage and control stage

控制IC介紹 UC 3842 Introduction n n Peak current mode control Using to Flyback converter or Forward converter Low start up current UVLO

UC 3842 Ratings

UC 384 X Electrical Characteristics

UC 3842 Applied Circuit

Circuit Configuration with UC 3842

UC 3842 Block Diagram

UC 3842 Oscillator

UC 3842 Error Amp Configuration

UC 3842 Current Sense Circuit

UC 3842 Drive Circuit

UC 3842 Isolated Drive Circuit

UC 3842 Soft-Start Circuit

What is Soft-Start? n When the converter is first switched on, the drive pulses should be progressively increased to allow a slow buildup in output current and voltage. If this soft-start action is not provided, there will be a large inrush current on initial switch-on.

Inrush Current 1. Soft-start 2. A resistive limiting device in series with the supply lines.

TL 494 Introduction n n Voltage mode control PWM IC Double output drive signal High power dissipation Adjustable deadtime control

TL 494 Ratings

TL 494 Applied Circuit

TL 494 Representative Block Diagram

TL 494 Oscillator

TL 494 Timing Diagram

TL 494 Pin Functions n n Pin 13 (output control pin): High level two output transistors alternately for pushpull operation. The output frequency is equal to half that of he oscillator. The duty of output drive signal is less than 0. 5. Low level two output transistors on/off operation. The output frequency is equal to that of he oscillator. The duty of output drive signal is less than 1. Pin 4 (deadtime control pin): Voltage level Duty

TL 494 Error Amp Sense Circuit

TL 494 Deadtime Control Circuit

TL 494 Soft-Start Circuit

TL 494 Output Drive Circuit

Isolation

Optocoupler Interface Circuit

Overvoltage Protection (I)

Overvoltage Protection (II)

Overvoltage Protection (III)