Description

The UCC3946DTR is a current-mode Pulse Width Modulated (PWM) controller used in off-line, flyback, or forward converters. It is designed to require a minimal number of external components for implementation. The controller contains all the necessary control and protection functions.

Specifications and features

■ Very low start-up supply current; 50 µA typical
■ Low operating supply current; 1.2 mA typical
■ Accurate, internally-trimmed, fixed frequency oscillator (100 kHz). No external timing components needed
■ Internal slope compensation. No external ramp components needed
■ Built-in over-voltage and under-voltage detection
■ High-speed over-current trip; 170 ns typical
■ Over-voltage clamp on supply voltage (VDD)
■ Internal divider regulates VDD to 12 V. No external divider needed
■ Leading edge blanking of the current sense signal
■ Control frequency modulated over a narrow band to reduce Electromagnetic Interference (EMI)
■ High output drive capability; 150 ns typical rise and fall time into 2 nF load
■ Wide bandwidth (10 MHz) error amplifier with external compensation pin and simple interface to optocoupler
■ Accurate internal bandgap reference.

Application Scenarios

■ Off-line switched mode power supplies
■ Laptop computer mains adaptors
■ Printer power supplies.

Comparison