Aimed at mobile devices, backlighting LED drivers run from single cell

August 15, 2012 // By Nick Flaherty
Intersil has launched a family of backlight LED drivers that can operate from the low input voltage of a single cell Li-ion battery.

The ISL9769x series features ultra-low quiescent current and high efficiency required to maximize battery life in the latest generation of smartphones, tablets and Ultrabook/notebook PCs.
With a minimum input voltage of just 2.4V, and quiescent current of only 0.8mA, the new ISL97692/3/4A series of LED drivers makes the most of the limited capacity of Li-Ion batteries in portable devices. The ISL97692 incorporates four channels with up to 40mA each, while the ISL97693 and ISL97694A provide six channels with up to 30mA each. All the drivers feature output current phase shifting which maximizes efficiency during PWM dimming and increases the effective output current frequency to eliminate audible noise. Additionally, when operating from a single cell Li-Ion battery, the drivers do not require any input voltage other than the battery, reducing board size and component count.
The devices are 90% efficient with a 3.7V input driving 6-parallel, 5-series LED configuration at 20mA/LED while the 0.8mA supply current and phase shifted PWM dimming improve energy efficiency and extend battery life. The 2.4V minimum input voltage allows operation from a single cell Li ion battery and reduces component count and they support a wide dimming range down to 0.025% duty cycle at 5kHz frequency. Phase shifting also multiplies the effective dimming frequency by the number of channels, permitting ultrasonic PWM dimming with 10-bit dimming resolution.
The ISL97692 and ISL97693 are available now in 16-lead TQFN packages. The ISL97694A is available in a 20-lead TQFN package. Prices start at $1.20 each in 1,000-unit quantities.