? DESCRIPTION

The UTC USR3654A is a primary control switch mode charger

and adapter applications. The controlled variable is transferred by

an auxiliary winding from the secondary to the primary side. The

device integrates PWM controller to enhance the performance of

discontinuous conduction mode (DCM) flyback converters.

The UTC USR3654A operates in primary-side sensing and

regulation. Opto-coupler and TL431 could be eliminated. It also

provides off-time modulation to linearly decrease PWM frequency

under light-load conditions so that low standby power can be

achieved.

The UTC USR3654A 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, VDD over voltage protection, VDD clamp, OTP,

leading edge blanking, VDD under voltage lockout, etc.

? FEATURES

* High Voltage startup circuit

* Built-in 650V Power MOSFET

* ±5% constant voltage regulation at universal AC input

* High precision constant current regulation at universal AC input

* Primary side control without TL431 and opto-coupler

* Programmable CV and CC regulation

* Programmable cable compensation in CV mode

* Flyback topology in DCM operation

* Frequency hopping to reduce system EMI

* Built-in leading edge blanking

* Built-in primary winding inductance

compensation

* Power on soft start

* Gate Output Maximum Voltage Clamped at

15V

* Cycle-by-cycle current limiting

* Over voltage protection

* VDD under-voltage lockout