1-chip display-power and LED driver for Smartphones

August 19, 2014 // By Graham Prophet
Intersil’s ISL98611 integrates the display power and backlight LED driver functions in a single chip. It significantly improves efficiency of both functions to potentially increase smartphone battery life by an hour or more.

In addition to extending battery life, the ISL98611 also improves display brightness uniformity and colour consistency. It integrates a boost regulator, LDO and inverting charge pump for generating two output rails at +5V and -5V in a single device. It also includes a boost regulator with 3-channel current sinks for the LED backlight driver. 

This single-chip solution offers designers four key benefits:

• Extended battery life: When used for web browsing and emails, a smartphone's backlight LEDs and display power consume the majority of its battery power. The ISL98611 backlight LED driver delivers 7% higher efficiency (up to 93%) than competitive multi-chip solutions and generates ±5V display power supplies with greater than 88% efficiency at 15 mA load using a 2.5 x 2 mm size inductor, compared to 85% efficiency of the nearest competitor.

• Improved display uniformity: The ISL98611 provides LED current matching at very low LED current: it achieves ±2.2% matching down to 1 mA and ±2.8% at 50 μA.

• Improved display colour consistency: The ISL98611 includes hybrid dimming to eliminate white LED colour shift issues at low LED current, which occur with DC dimming.

• It uses 24% less PCB area compared to the competition, while requiring only eight external components.

In a 2.33 x 2.61 mm 30-ball WLCSP package the part costs $1.50 (1000). An evaluation board, ISL98611EVAL1Z, is $100..

Intersil; www.intersil.com/products/ISL98611