ADT7110
Application Hints
(continued)
Example : typical application circuit
N = 6 (6 LED branches)
V
IN
= 12V , V
OUT
= 9V
ICC = 280mA (measured) , and efficiency is 80%.
So, calculated 1 branch LED current is 49.77mA.
▶
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.
* This specifications are subject to be changed without notice
Jun. 07. 2008 / Rev. 0.1
7/8
http://www.ad-tech.co.kr
ADTECH [ ADTECH ]
