STCF01 VOLTAGE REGULATOR
White LED driver for cell phone camera flash

The STCF01 is designed to drive two, three, or four white, cell phone camera flash LEDs with constant current. The step-up (boost) PWM converter input is connected directly to the battery, and ranges from 2.6V to 5.5V. The converter output voltage is automatically determined using current feedback-based duty cycle control. The boost topology is needed because the white LED forward voltage (Vf) is about 3.6V (typ).

The maximum Output Current (IO) is limited by inductor peak current which is internally set at 1.2A (typ). This allows for the use of low-profile inductors, as well as limits the current drained from the battery.
The STCF01 is able to work in two operating modes. The Select (SEL) pin is dedicated to White LED current flow selection for these modes. An external resistor is used to set the required current for each level, using the following formulas:

FLASH Mode
ILED (FLASH) = 2100 * (VI - VHC) / RHC
Where VSEL = 3V, high current of up to 300mA can be achieved, and RHC = 4kΩ.

TORCH Mode
ILED (TORCH) = 2400 * (VI - VLC) / RLC
Where VSEL = GND, maximum allowable current is 100mA, and RLC = 12kΩ.
The Shutdown (SHDN) pin saves power when the camera flash is not used by consuming less than 0.1µA of current.

DFN10L (3mm x 3mm)