Date: 26/10/2010

New multi-channel LED drivers from Intersil reduces undesirable backlight-induced visual artifacts

Intersil Corporation has released a new family of innovative multi-channel LED drivers that provide an ultra-low dimming capability that extend battery life in notebook, netbook and tablet computers. The ISL97671/2/3/4 series reduces undesirable backlight-induced visual artifacts such as flickering, shimmering and banding that are observed when using conventional LED drivers. The devices minimize power loss by using a proprietary dynamic headroom control circuit to detect the highest voltage LED string, and then regulate the boost output to the minimum required voltage.

The ISL97671/2/3/4 drive up to six 40mA strings of LEDs from a 4.5V to 26V input. The device provides a highly accurate LED current matching circuit thta achieves ±0.7% current matching between LED strings. The ISL97671/2/3/4 series also includes an integrated boost converter to step-up the input voltage to support LED stack voltages up to 45V.

The drivers maintain dimming linearity even at low LED PWM duty cycles by using an adaptive boost control circuit that regulates the output voltage even when the LEDs are off for most of the PWM cycle. The ISL97671/2/3/4 series provides dimming down to just 0.007% of full brightness with a 200Hz PWM frequency. Dimming may be controlled by direct PWM dimming or by using 8-bit digital dimming via an I2C/SMBus interface.

The devices' phase shift capability can turn LED strings on at a specified phase, reducing peak input current by distributing channel currents within the dimming period. This device offers protection features such as over-temperature protection, over-voltage protection and LED open/short circuit protection. The devices integrate power MOSFETs for the boost converter and channel regulation circuitry.

Package: 20-lead 4mm x 3mm QFN

Price: US$1.80 for 1K pieces

Avaiability: Now