DESCRIPTION

The UTC UC3844/3845 are high performance fixed frequency current mode controllers that specifically designed for Off-Line and DC to DC converter applications with minimal external parts count. The differences between UC3844 and UC3845 are the maximum duty cycle ranges and under-voltage lockout thresholds. The UC3844 ideally suited to off-line applications with UVLO thresholds of 16V(ON) and 10V(OFF), and UC3845 has UVLO thresholds of 8.5V(ON) and 7.6V(OFF) for lower voltage applications.

FEATURES

* Operation output switching frequency up to 500 kHz

* Output deadtime adjustable from 50% to 70%

* Automatic feed forward compensation

* Latching PWM for cycle-by-cycle current limiting

* High current totem pole output

* Internally trimmed reference with under voltage lockout

* UVLO with hysteresis

* Low startup and operating current