HIGH PERFORMANCE CURRENT MODE PWM CONTROLLERS

DESCRIPTION

The UTC UC1844/1845 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 UC1844 and UC1845 are the

under-voltage lockout thresholds. The UC1844 ideally suited to

off-line applications with UVLO thresholds of 16V(ON) and 10V(OFF),

and UC1845 has UVLO thresholds of 8.4V(ON) and 7.6V(OFF) for

lower voltage applications.

FEATURES

* Operation output switching frequency up to 500 kHz

* 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