EL7513 led driver circuit

A very simple white led driver schematic circuit can be designed using the EL7513 constant current boost regulator specially designed for driving white LEDs. It can drive 4 LEDs in series or up to 12 LEDs in parallel or series configuration and achieves efficiency up to 91%.
The brightness of the LEDs is adjusted through a voltage level on the CNTL pin.
This voltage can be either a DC or a PWM signal
with frequency less than 200Hz (for C3 = 4700pF). When a higher frequency PWM is used, an RC filter is recommended before the CNTL pin .When the level falls below 0.1V, the chip goes into shut-down mode and consumes less than 1μA of supply current for VIN less than 5.5V.

EL7513 is operated in constant frequency PWM. The switching is around 1MHz.
As you can see this circuit diagram led driver is designed for maximum efficiency , and drives 3 legs of 4 LEDs in a series configuration . The input voltage required for this led driver application circuit must be around 2.7 and 4.2 volt , typically 3.3 volt .
The parts list for this LED driver schematic circuit is : C1 = 4.7μF, C2 = 1μF, C3 = 0.1μF, L = 33μF, VCNTL = 1V, R1 = 5Ω .