UC3842

Philips Semiconductors Linear Products Product specification Current-mode PWM controller UC3842 DESCRIPTION The UC3842 is available in an 8-Pin mini-DIP the necessary features to implement off-line, fixed-frequency current-mode control schemes with a minimal external parts count. This technique results in improved line regulation, enhanced load response characteristics, and a simpler, easier to design control loop. Topological advantages include inherent pulse-by-pulse current limiting. Protection circuitry includes built-in undervoltage lock-out and current limiting. Other features include fully-latched operation, a 1% trimmed bandgap reference, and start-up current less than 1mA. These devices feature a totem-pole output designed to source and sink high peak current from a capacitive load, such as the gate of a power MOSFET. Consistent with N-channel power devices, the output is low in the OFF-state. PIN CONFIGURATIONS N Package COMP VFB ISENSE RT/CT 1 2 3 4 TOP VIEW 8 7 6 5 VREF VCC OUTPUT GROUND D Package COMP 1 2 3 4 5 6 7 TOP VIEW 14 VREF 13 NC 12 V CC 11 V C 10 OUTPUT 9 8 GROUND POWER GROUND FEATURES NC VFB NC ISENSE NC RT/CT Low start-up current (≤1mA) Automatic feed-forward compensation Pulse-by-pulse current limiting Enhanced load response characteristics Undervoltage lock-out with hysteresis Double pulse suppression High current totem-pole output Internally-trimmed bandgap reference 400kHz operation, guaranteed min BLOCK DIAGRAM APPLICA...