ADT7110 Datasheet, PDF(7/8 Page) ADTech – fixed frequency step-down converter designed to drive Infrared LEDs in the CCD camera module application

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ADT7110 Datasheet, PDF (7/8 Pages) ADTech – fixed frequency step-down converter designed to drive Infrared LEDs in the CCD camera module application

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Application Hints (continued)

Example : typical application circuit

N = 6 (6 LED branches)

VIN = 12V , VOUT = 9V

ICC = 280mA (measured) , and efficiency is 80%.

So, calculated 1 branch LED current is 49.77mA.

â¶ Dimming control

The LED brightness control can be obtained by forcing a

pulse wave to the EN input terminal. Typically, a 100Hz to

1kHz pulse signal is used. LED brightness is proportional to

the duty of pulse wave. And in this case , LED branch current

is RMS value of the PWM modulated current.

When the pulse-width is below 50% duty, the driving current

of ADT7110 can be increased up to current limit

condition.(~550mA) But you keep carefully to select the

inductor (L1) over 700mA rated current.

Note that the inductor (L1) is 590mA rated in typical

application circuit.

ADT7110

* This specifications are subject to be changed without notice

Jun. 07. 2008 / Rev. 0.1

7/8

http://www.ad-tech.co.kr

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