Multi-string LED drivers brighten in-vehicle infotainment displays

February 24, 2014 // By Paul Buckley
Integrated Silicon Solution, Inc. ( ISSI ) has unveiled two highly integrated multi-string LED drivers that enable rich video imaging in backlighting automotive LCD displays.

The IS32BL3552 and IS32BL3554 high performance devices integrate a boost converter with multiple current sinks for cost-effective automotive infotainment displays and instrument clusters, as well as applications in industrial displays, TVs and monitors.

ISSI's LED drivers include a DC-DC boost switching controller with outputs up to 60 V to drive multiple strings of LEDs as well as regulated current sinks with string-to-string current matching accuracy of ±1.5% to ensure uniform LCD display brightness. The IS32BL3552 supports two parallel strings of up to 360 mA each, while the IS32BL3554 supports four strings of up to 180 mA. For added flexibility, the sinks can be paralleled together to achieve even higher LED currents.

Both products incorporate multiple protection features to prevent damage during a fault condition. An internal soft-start circuit prevents a high inrush current during startup, and thermal shutdown protection shields the IC from thermal damage. Both devices monitor the LED string condition for open or shorts and automatically disable any faulty current sinks.

Designers will benefit from smaller PCB footprints and lower BOM costs due to the high frequency operation of the boost converter. The addition of an external resistor allows for frequencies up to 1 MHz. The device can be PWM modulated over a wide frequency range from 20 Hz to 20 kHz to provide a high contrast ratio. In addition, the lower external component count will enhance system reliability. No additional external circuitry is required to implement advanced functions such as open and short LED protection and high contrast PWM dimming.

The IS32BL3552 and IS32BL3554 are fully specified across the -40°C to +125°C automotive temperature range, while operating over a wide input-voltage of 4.5 V to 33 V. The devices are offered in low profile 16-pin thermally enhanced TSSOP packages with an exposed thermal pad.


Prices start at $1.29 for IS32BL3552 and $1.39 for IS32BL3554 in 1,000 piece quantities.