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 19/35
Step 4 Dimming Control
Two ways to implement the LED dimming are offered: the analog dimming and the PWM dimming. Both methods control the
average current flowing through the LEDs.
Analog dimming
The analog dimming can be achieved adjusting the LED current by using an external voltage source (V
ADIM
), as shown in the
schematic below:
C
IN
LED+
DIM
PGND
ISET
IFIX
LED-
Module
AGND
1
3
EP
6
V
IN
2
LED+
7
5
4
R
IADJ
R
ADIM
V
ADIM
High Power LED String
C
OUT
Variable
volta ge source
The LED current can be adjusted from I
LEDmax
to I
LEDmin
by selecting the resistor R
IADJ
and R
ADIM
, as described by the
following equations:
R

=
V

∙k
I
,
−I
,
(3)
R

=
V

∙V

∙k
V

∙I
,
−V

∙ (I
,
−I
,
)
(4)
where V
REF
= 1.25V and k is the current mirror ratio (internally set to 840).