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 27/35
Similarly, in case the LED is only temporary shorted and then again normally working, the voltage across the LED string will
be adapted accordingly. In any case the current through the LED string is not affected, keeping the programmed value.
Open LED behavior
LED or string open
0mA
V
IN
18V
350mA
3V
3V
3V
3V
3V
3V
3V
3V
3V
3V
3V
When a LED becomes an open circuit or simply the LED string is disconnected by the LED driver, the current stops flowing
through the LED string. As consequence the control loop will set the voltage between LED+ and LED- to the input voltage
(V
IN
), as shown below:
Monitoring the LED string voltage by an external microcontroller allows the detection of defective strings.
0
0,3
0,6
0,9
1,2
1,5
0
5
10
15
20
25
30
0 100 200 300 400 500 600
LED Current [A]
LED Voltage [V]
Time [µs]
Behavior of the LED driver in case of open LED or open string
LEDopen
VLED
VIN
LED current=350mA
LED current= 0mA