The UC3842A, UC3843A series of high performance fixed frequency current mode controllers are specifically designed for off–line and dc–to–dc converter applications offering the designer a cost effective solution with minimal external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and a high

current totem pole output ideally suited for driving a power MOSFET.

The UCX842A has UYLO thresholds of 16 V (on) and 10 V (off), ideally suited for off–line converters. The UCX843A is tailored for lower voltage applications having UVLO thresholds of 8.5 V (on) and 7.6 V (off).

? Trimmed Oscillator Discharge Current for Precise Duty Cycle Control

? Current Mode Operation to 500 kHz

? Automatic Feed Forward Compensation

? Latching PWM for Cycle–By–Cycle Current Limiting

? Internally Trimmed Reference with Undervoltage Lockout

? High Current Totem Pole Output

? Undervoltage Lockout with Hysteresis

? Low Startup and Operating Current

? Direct Interface with Motorola SENSEFET Products