Datasheet
Data Sheet
©2014
Würth Elektronik eiSos GmbH & Co. KG - REV 0.1
PRELIMINARY
12/ 21
172946001
MagI³C Power Module Product Family
LDHM - LED Step Down High Current Module
Step 4. Dimming Control
The DIM pin of the LED driver module is an input with internal pull-up that accepts logic signals for average LED
current control. Applying a logic high (above 1.3 V) signal to the DIM pin or leaving the DIM pin open will enable the
device. Applying a logic low signal (below 0.7 V) to the DIM pin will disable the switching activity of the device but
maintain operation of the VCC regulator active. The LED driver module operation of high speed dimming and very
fine dimming control is shown below.
LED driver module current regulation
I
LED
Time
LED off
LED
start up
LED regulation
LED current increase
0
30D
Step 5. Parallel operation
When a load current higher than 450 mA is required by the application, LED driver module can be used in parallel to
deliver higher current. With common V
INs
and GNDs, the LED driver module will operate as independent
asynchronous current sinks driving the same LED load. The total DC current of the modules will be additive; however,
low frequency sub-harmonic current ripple may be present and its frequency and magnitude will depend upon the
phase relationship between the internal clocks as there is no provision for synchronizing driver clocks. It is suggested
to have minimum 2.2 μF C
OUT
located close the module to filter out the current ripple, and the resultant LED current
will become DC. Current sharing modules should have a local CIN capacitor of minimum 2.2 μF located as close to
V
IN
and GND as possible. Refer to “Parallel operation circuit schematic” for the LED driver module parallel operation
circuit schematic. Refer to “Parallel operation result” for the LED driver module parallel operation results I
LED
vs V
IN
.
Parallel operation circuit schematic
05S
1 2 3 4 5 6 7
LED+
LED+
DIM
GND
VREF
IADJ
LED-
Exposed Pad
(EP)
C
IN
V
IN
R
VREF
C
OUT
1 2 3 4 5 6 7
LED+
LED+
DIM
GND
VREF
IADJ
LED-
Exposed Pad
(EP)
C
IN
R
VREF
C
OUT
High Power LED Array
Module Module
I
LED1
I
LED2
31D
Parallel operation result; I
LED
= 900mA
LED Current (A)
Input Voltage (V)
0 10 20 30 40 50 60
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1LED
9LED
16LED