Lumissil Microsystems, a division of Integrated Silicon Solution, Inc. (ISSI), announced today an LED driver to further expand its portfolio of automotive exterior lighting solutions. The IS32LT3959 is a single inductor, multi-topology controller with constant on-time for driving a ground referenced high-voltage LED string. This single channel switching LED driver integrates a PWM engine with external control to achieve dual brightness capability for Rear Combination Lamp (RCL), Daytime Running Lamp (DRL) and headlights.

The IS32LT3959 switching LED driver supports advanced features such as ultra-low 1.5µA shutdown current to conserve battery power, 3% output current accuracy for optimal LED brightness control, programmable Pulse-Width Modulation (PWM) engine for standalone LED dimming capability and spread spectrum to minimize the device EMI profile. Other key features are programmable single LED short detection, both analog and digital dimming, LED current monitoring pins, device and LED temperature monitoring, single inductor requirement for all switching topologies and comes in a thermally enhanced eTSSOP-28 package. It operates from a wide 4.5 to 55V supply voltage and is guaranteed to meet specifications over the -40°C ~ +150°C operating temperature range.

“The IS32LT3959 is our latest automotive-compliant, AEC-Q100 LED driver designed to meet the demands of next generation exterior vehicle lighting designs,” said Ven Shan, Vice President of Marketing. “This driver incorporates the latest features in a compact 28-pin package to provide power and space savings; while at the same time lowering the overall system costs due to its many integrated functions.”

The integrated PWM engine can be configured to operate up to 2kHz with a 5 to 95% duty cycle. A single pin will enable or disable the PWM engine so that when enabled the LED current level is subject to the PWM duty cycle and when disabled the maximum current is output to the LED string. This support for two LED current levels enables cost effective lighting systems since the same LEDs can be used for both tail and brake lamps. This dual brightness capability can also be used with DRL for higher brightness during the daytime and a lower brightness level at nighttime.

Availability and pricing

The IS32LT3959 is available now in production quantities, with AEC-Q100 qualification and supporting PPAP documentation. The device comes in a thermally enhanced 28-pin TSSOP package is priced at $0.95 each in 10k pcs quantities.

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