MP4657AGS

The MP4657A is a single-stage, flyback, 4-string LED driver and system voltage (VSYS) controller for LED backlighting on the secondary side. It controls the flyback power stage and an external N-channel MOSFET to regulate the system output voltage (VOUT) and the LED current loop via integrated 4-string LED current balancing. With a 4V to 16V input voltage (VIN), the MP4657A outputs a direct driving signal to control the N-channel MOSFET that regulates VOUT. It also outputs a compensation signal to control the primary-side flyback (or other power stages) via an optocoupler. The device supports pulse-width modulation (PWM) dimming and analog dimming to the LED current (ILED) via the ADIMP/PWM pin. For analog dimming, apply a pulse signal with a >5kHz frequency to this pin. For PWM dimming, apply a pulse signal with a <5kHz frequency. The MP4657A uses an individual control method for ILED and VSYS. If the PWM signal is effective, then the LED current loop is regulated via the flyback power stage, and VSYS is further regulated by the N-channel MOSFET. Soft switching of the N-channel MOSFET reduces voltage spikes. If the PWM signal is ineffective, then the flyback power stage controls VSYS. Full protection features include LED open protection, LED short protection, LEDx pin short-to-ground protection, over-voltage protection (OVP), feedback (FB) open-loop protection, and thermal shutdown. The MP4657A is available in an SOIC-16 package.