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National Semiconductor has announced an LED driver with temperature-management control and an online design environment to support it.

The LM3424, a member of National’s Powerwise energy-efficient product family, drives high-brightness LEDs in a variety of indoor, outdoor and automotive applications.

Supported in National’s Webench LED Designer, its temperature-management control, thermal foldback, enables lighting designers to design a reliable thermal system using the LM3424.

Thermal foldback combats high temperatures LEDs can reach as a result of environmental conditions.

With the LM3424, lighting designers can programme temperature and slope breakpoints within which the LEDs operate safely.

When an over-temperature condition occurs, the LM3424’s thermal-foldback circuitry reduces the regulated current through the LEDs.

The reduced current dims the LED to a range programmed by the designer and the LED remains within the range until it returns to a safe operating temperature.

This method of thermal foldback maintains the lifetime and efficacy of the LED, and ensures the warranty period of fixtures in applications such as automotive headlights, high-bay warehouse lighting and street lighting.

National’s Webench LED Designer helps lighting designers identify the ideal temperature threshold or foldback breakpoint of the LEDs.

The online design environment allows the designer to enter the temperature foldback and slope points and then visualise the behaviour of the design at different LED temperatures.

An interactive temperature slider shows the results graphically.

The LED driver design automatically updates with entry of temperature breakpoint requirements.

Offered in a 20-pin thermally enhanced TSSOP package, the LM3424 drives up to 18 high-brightness LEDs in series with output current above 2A in a typical application.

It contains all of the features to regulate currents based on buck, boost, SEPIC, flyback and buck-boost topologies.

The LM3424 operates over an input range of 4.5 to 75V.

The pulse-width modulation (PWM) controller is designed for high-speed capability, including an oscillator frequency range that can be synchronised up to 2.0MHz.

Additional features include PWM and analogue dimming, programmable softstart and protection features such as low power and thermal shutdown, and cycle-by-cycle current limit.

National Semiconductor

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