L4990D

主控制器 PRIMARY CONTROLLER

DESCRIPTION

This primary controller I.C., developed in BCD60II technology, has been designed to implement off line or DC-DC power supply applications using a fixed frequency current mode control. Based on a standard current mode PWM control ler this device includes some features as programmable soft start, IN/OUT synchronization, disable to be used for over voltage protection and for power management, precise maximum Duty Cycle Control, 100ns typ leading edge blanking on current sense, pulse by pulse current limit and overcurrent protection with soft start in tervention.

■ CURRENT-MODE CONTROL PWM

■ SWITCHING FREQUENCY UP TO 1MHz

■ LOW START-UP CURRENT < 0.45mA

■ HIGH-CURRENT OUTPUT DRIVE SUITABLE FOR POWER MOSFET 1A

■ FULLY LATCHED PWM LOGIC WITH DOUBLE PULSE SUPPRESSION

■ PROGRAMMABLE DUTY CYCLE

■ 100% AND 50% MAXIMUM DUTY CYCLE LIMIT

■ PROGRAMMABLE SOFT START

■ PRIMARY OVERCURRENT FAULT DETECTION WITH RE-START DELAY

■ PWM UVLO WITH HYSTERESIS

■ IN/OUT SYNCHRONIZATION

■ DISABLE LATCHED

■ INTERNAL 100ns LEADING EDGE BLANKING OF CURRENT SENSE

■ PACKAGE: DIP16 AND SO16W