Data Sheet

WLMDU9456001JT / 172946001
MagI
3
C Power Module
LDHM - LED Step Down High Current Module
We-online.com Würth Elektronik eiSos GmbH & Co. KG – Data Sheet Rev. 1.0
© May 2016 23/35
Example 2. Assuming to keep the on-time of the PWM signal always equal to the t
DIM,on_min
, varying the frequency of the
PWM signal (PFM LED brightness control), the LED brightness can be adjusted as well as different contrast ratios can be
achieved (see picture below):
16µs
f
DIM
> 250Hz
16µs
f
DIM
= 250Hz
16µs
f
DIM
< 250Hz
Darker LED
Brighter LED
Higher CR
Lower CR
The constant duration of the LED on-time limits the LED junction temperature increase during dimming. As consequence,
the efficiency of this brightness control is higher compared to the PWM control.