Constant-current DC/DC converter drives up to 17 high-brightness LEDs

November 02, 2012 // By Christoph Hammerschmidt
A combination of constant current DC/DC converter with frequency synchronization, PWM dimming and thermal foldback, the TPS92510 from Texas Instruments offers a range of innovative design options for lighting developers - in particular if the used together with TI's Webench LED architect design tool.

Unlike conventional buck LED drivers, the TPS92510 can operate with fixed frequency either by utilizing its internally-generated clock or via synchronization to an external PWM clock source. In multi-string implementations, the use of an external clock eliminates beat frequencies that may be visible in the lighting application and simplifies EMI filter design. Thermal foldback ensures some light output remains even in an LED over-temperature condition, which improves safety in the lighting environment.

The TPS92510 joins TI's LED driver portfolio that includes the 0.5-A LM3402, 1.0-A LM3404 and 1.5-A LM3406 hysteretic, non-synchronous, constant current LED buck regulators that feature LED open circuit protection, low-power shutdown and thermal shutdown. Designers can use it to create power management circuits to drive a string of up to 17 high-brightness LEDs at up to 97-percent power efficiency in automotive, industrial and general illumination applications.

Key features and benefits of the TPS92510 LED driver include

• 3.5-V to 60-V input voltage operating range supports a wide variety of DC LED lighting applications, including area and street lighting.

• Fixed switching frequency range from 100 kHz to 2.5 MHz can be synchronized to optimize for efficiency or solution size.

• LED thermal foldback with external negative temperature coefficient (NTC) protects LED array from over-temperature while maintaining reduced light output.

• Dedicated PWM dimming input from 100 Hz to 1 kHz adjusts LED brightness without color shift or perceivable flicker.

The TPS92510 is available in volume now from TI and its authorized distributors. Offered in a 4.9-mm by 3-mm, 10-pin PowerPad MSOP package, the TPS92510 is priced at US$1.65 each in 1,000-unit quantities.

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