AMC3842B

AMC DOC. #: AMC3842B_C (LF) March 2004 ® AMC3842B/43B CURRENT MODE PWM CONTROLLER FEATURES ADD MICROTECH CORP. DESCRIPTION The AMC3842B/43B are fixed frequency current-mode PWM controllers specially designed for OFF-Line switching power supply and DC-to-DC converters with a minimum number of external components. These devices feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem pole output which is suitable for driving MOSFETs. The under voltage lock-out (U.V.L.O.) is designed to operated with 200µA typ. start-up current, allowing an efficient bootstrap supply voltage design. The U.V.L.O. thresholds for the AMC3842B are 16V (on) and 10V (off) which are ideal for off-line applications. The corresponding typical threshold for the AMC3843B are 8.4V (on) and 7.6V (off). The AMC3842B/43B can operated within 100% duty cycle. APPLICATIONS Low Start-Up current ( typ. 200µA) Optimized for Off-Line and DC-to-DC Converters Maximum Duty Cycle U.V.L.O. with Hysteresis Operating Frequency Up to 500KHz Internal Trimmed Bandgap Reference High Current Totem Pole Output Error Amplifier With Low Output Resistance Available in 8-Pin Plastic DIP and Surface Mount 14-Pin S.O.I.C. Identical pin assignment to earlier UC384X series. PACKAGE PIN OUT COMP VFB ISENSE RT/CT VREF VCC OUTPUT GND Off-line flyback or forward converters. DC-to-DC buck or boost converter. Monitor Powe...