Li-Ion Driver for 8 White LEDs

We can use boost converter such as TPS61160/1 with a 40V rated integrated switch FET to drive up to 10 LEDs in series. We can use it to reduce output ripple, improve conversion efficiency, and allows for the use of small external component. The external sensor resistor Rset is set on the default white LED current with feedback voltage is regulated to 200mV. The LED current can be controlled using the 1-wire digital interface through the CTRL pin during the operation or we can use a pulse width modulation (PWM) signal which is apply to the CTRL pin through which the duty cycle determines the feedback reference voltage. For maximum protection, the device features integrated open LED protection that turn the TPS61160/1 off during open LED conditions to prevent the output from exceeding the absolute maximum ratings.

The features of the device  are detailed below:

• 200mV Reference Voltage With +- 2% Accuracy
• Flexible DIgital and PWM Brightness Control
• Built-in Soft Start
• Up to 90% Efficiency
• 2mmx2mmx0.8mm 6-pin QFN Packacge With Thermal Pad
• 2.7V to 18V Input Voltage Range
• 26V Open LED Protection for 6 LEDs (TPS61160)
• 38V Open LED Protection for 10 LEDs (TPS61161)

And applicable on device such as:

• Cellular Phones
• GPS Receivers
• White LED Backlighting for Media Factor Display
• Portable Media Players
• Ultra Mobile Device

[Source: Texas Instruments Application Note]