application
INFO
available UCC1581
UCC2581
UCC3581 Micropower Voltage Mode PWM
FEATURES BLOCK DIAGRAM Low 85ВµA Startup Current Low 300ВµA Operating Current Automatically Disabled
Startup Preregulator Programmable Minimum Duty
Cycle with Cycle Skipping Programmable Maximum
Duty Cycle Output Current 1A Peak
Source and Sink Programmable Soft Start Programmable Oscillator
Frequency External Oscillator
Synchronization Capability Note: Pin Connection shown for 14-pin Package UDG-95011-1 DESCRIPTION
The UCC3581 voltage mode pulse width modulator is designed to control low power isolated DC -DC converters
in applications such as Subscriber Line Power (ISDN
I.430). Primarily used for single switch forward and
flyback converters, the UCC3581 features BiCMOS circuitry for low startup and operating current, while maintaining the ability to drive power MOSFETs at
frequencies up to 100kHz. The UCC3581 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.
The UCC3581 includes programmable soft start circuitry,
overcurrent detection, a 7.5V linear preregulator to control chip VDD during startup, and an on-board 4.0V logic
supply. …
