UC3868

www.DataSheet4U.com UC1861-1868 UC2861-2868 UC3861-3868 Resonant-Mode Power Supply Controllers FEATURES DESCRIPTION Controls Zero Current Switched (ZCS) The UC1861-1868 family of ICs is optimized for the control of Zero Curor Zero Voltage Switched (ZVS) rent Switched and Zero Voltage Switched quasi-resonant converters. DifQuasi-Resonant Converters ferences between members of this device family result from the various combinations of UVLO thresholds and output options. Additionally, the Zero-Crossing Terminated One-Shot one-shot pulse steering logic is configured to program either on-time for Timer ZCS systems (UC1865-1868), or off-time for ZVS applications (UC1861 Precision 1%, Soft-Started 5V 1864). Reference The primary control blocks implemented include an error amplifier to com Programmable Restart Delay pensate the overall system loop and to drive a voltage controlled oscillator Following Fault (VCO), featuring programmable minimum and maximum frequencies. Triggered by the VCO, the one-shot generates pulses of a programmed maxi Voltage-Controlled Oscillator (VCO) mum width, which can be modulated by the Zero Detection comparator. with Programmable Minimum and Maximum Frequencies from 10kHz to This circuit facilitates “true” zero current or voltage switching over various line, load, and temperature changes, and is also able to accommodate the 1MHz resonant components' initial tolerances. Low Start-Up Current (150µA typical) Under-Voltage Lockout is incorporated...