[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.

FEATURES

■ 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.

APPLICATIONS

■ Off-line flyback or forward converters.

■ DC-to-DC buck or boost converter.

■ Monitor Power Supply