DESCRIPTION
The UTC UC1100 is a primary control unit for switch mode charger and adapter applications. The controlled variable is transferred by an auxiliary winding from the secondary to the primary side. The device uses Pulse Frequency Modulation (PFM) method to build discontinuous conduction mode (DCM) flyback power supplies.
The UTC UC1100 operates in primary-side sensing and regulation. Opto-coupler and TL431 could be eliminated. It also eliminates the need of loop compensation circuitry while maintaining stability. The UTC UC1100 achieves excellent regulation and high average efficiency, yet meets the requirement for no-load consumption less than 30mW.
The UTC UC1100 achieves high precision CV/CC regulation and high power efficiency. It offers comprehensive protection coverage with auto-recovery features including Cycle-by-cycle current limiting, output over voltage protection, feedback loop open protection, short circuit protection, leading edge blanking, VCC under voltage lockout, etc.

FEATURES
* Primary side control for rectangular constant current and constant voltage output
* 30mW no-load input power feasible
* Tight CC regulation performance
* Sub-microampere start-up current
* Eliminates control loop compensation circuitry
* Eliminates opto-coupler and secondary CV/CC control circuitry
* Random frequency modulation to reduce system EMI
* Flyback topology in DCM operation
* Open feedback protection
* Built-in soft start
* Short circuit protection