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LED driver allows wide dimming range

Posted: 29 Aug 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Maxim? MAX16804? LED driver?

Maxim's MAX16804 LED driver

Maxim Integrated Products has introduced the MAX16804, a 350mA, high-brightness LED driver. The company said the new device features a high-voltage (40V) PWM pin that allows a wide dimming range. An operating input-voltage range of 5.5-40V helps protect against large transients such as load-dump and cold cranking, Maxim said. These features make the MAX16804 suitable for automotive, LED industrial, and architectural lighting applications.

An on-board 200Hz ramp generator allows analog or PWM control for PWM or theatre-dimming effect, said Maxim, thus eliminating the need for the microcontroller's PWM signal. The high-voltage (40V-rated) DIM pin can also sync with an external PWM signal up to 2kHz. Fast turn-on/off times provide a wide dimming range, the company said, while the wave-shaping circuitry minimizes EMI. A fixed, 5V-output regulator delivers up to 2mA of load current for low-power applications throughout the 5.5V to 40V input-voltage range.

For greater design flexibility, the regulator can also power a microcontroller or other external components. The regulator stays on even when DIM is pulled low. The device's regulator combines a low-voltage (204mV) current-sense reference with differential LED current sensing to provide load accuracy of 3.5 percent. This current accuracy allows consistent brightness for all light assemblies, Maxim said. The device's low-dropout pass element (0.5V, typ) and current-sense reference minimize power dissipation in the system. They can drive multiple LEDs in series up to 39V. The need for only two small ceramic capacitors and a small sense resistor results in minimal board size and driver cost, according to the company.

MAX16804 features thermal and short-circuit protection and is rated for operation over the automotive temperature range (-40C to 125C). It is available in a thermally enhanced, surface-mount, 5-by-5mm 20-pin TQFN Pb-free package rated at 2.67W power dissipation. Pricing starts at $1.31 (1,000-up, FOB USA).

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