The UCC2581D is a voltage mode Pulse Width Modulation (PWM) designed to control low power isolated DC to DC converters in applications such as subscriber line power (ISDN I.430). Primarily used for single switch forward and flyback converters, it features BiCMOS circuitry for low startup and operating current, while maintaining the ability to drive power MOSFETs at frequencies up to 100kHz. The oscillator allows the flexibility to program both the frequency and the maximum duty cycle with two resistors and a capacitor. A TTL level input is also provided to allow synchronization to an external frequency source. It includes programmable soft start circuitry, overcurrent detection, a 7.5V linear pre-regulator to control chip VDD during startup and an on-board 4V logic supply. It provides functions to maximize light load efficiency that are not normally found in PWM controllers.
Low 85μA Startup current
Low 300μA Operating current
Automatically disabled startup preregulator
Programmable minimum duty cycle with cycle skipping
(EN)
