Another LED driver circuit based on the MP3302 LED driver IC. This circuit can drive 9 parallel strings of three white LEDs in series and can be operated from a 3V DC supply and it is suitable for single cell applications.
The figure shown below (Fig 3) is of an LED driver circuit that can be operated from a wide supply voltage range (3.3V to 18V). This circuit too is based on the MP3302 LED driver IC. An extra bias circuit comprising of resistor R and Zener diode D is added inorder to make the ON resistance of the power MOSFET low and make the chip compatible to high input voltages. This circuit can drive 3 parallel strings of 9 white LEDs in series. Remaining part of the circuit is similar to the LED driver shown in Fig 2.