The RT4503/A is a highly integrated LED driver IC capable of driving 10 WLEDs in series. It is composed of a current mode Boost converter integrated with a 36V/1.2A power switch.
The RT4503/A supports a wide input voltage range from 2.5V to 5.5V and runs at a fixed frequency of 550kHz. The LED current is set via an external resistor and the feedback voltage is regulated to 200mV.
For brightness dimming, the RT4503A supports 32 steps pulse dimming which determines the feedback reference voltage, and RT4503 support PWM dimming which determines the feedback reference voltage.