The HT7L4661 is a Buck converter controller using quasi-resonant conversion technology. It can be used for driving high-brightness LEDs with power factor correction in off-line applications. The controller is implemented by driving an external power MOSFET and measuring and regulating a constant LED current. Additional features in the device include a rapid high voltage startup function and a 5V LDO output with a 1mA drive capability for external loads. There is also a linear dimming function to adjust the LED illumination level. The HT7L4661 also includes multiple protection features to protect it from fault conditions. These include under-voltage lockout, over-current protection, Vcc pin over-voltage protection and a ZCD pin overvoltage protection for the output voltage. Additionally, to ensure device reliability, there is also a fully integrated thermal protection function.

Features

Non-isolation buck topology
Wide AC input range − from 85VAC to 265VAC
High Power Factor of >0.9 without additional circuitry
Internal 650V high voltage JFET for quick startup
Provides 5V LDO output
Accurate constant current (< ±3%)
Includes linear dimming function
Low operating current to maximise conversion efficiency
Under-voltage lockout with hysteresis
Full protection functions for enhanced safety
– Maximum gate drive output clamp
– VCC over voltage protection — VCC OVP
– VCC under-voltage lockout with hysteresis — VCC UVLO
– Output LED string over current protection
– Output LED string short protection
– Output LED string open protection
– CS, ZCD pins open protection
– On-chip Vver temperature protection — OTP
Small 10-pin MSOP package