Datasheet
Data Sheet
©2014
Würth Elektronik eiSos GmbH & Co. KG - REV 0.1
PRELIMINARY
10/ 21
172946001
MagI³C Power Module Product Family
LDHM - LED Step Down High Current Module
N CIRCUIT DESCRIPTION
MagI³C 3+2 Steps to design the current driver application
The next 5 simple steps will show how to select the external components to design your power application:
1. Program the LED driver module current
2. Layout considerations
3. EMI design considerations
4. Optional: Dimming control
5. Optional: Parallel operation
C
IN
LED+
LED+
DIM GND VREF
IADJ
LED-
Module
V
IN
Exposed Pad
(EP)
I
LED
I
IN
High Power LED String
02S
R
IADJ
R
VREF
Step 1. Program the LED driver module current
The LED driver module requires no external current sensing resistor for LED current regulation. The average LED
current of the LED driver module is adjustable from 300 mA to 450 mA by varying the resistance of the resistor
according to the following equation and table.
Conditions:
= open;
<= 499 Ω
(1)
Conditions:
= 0;
>= 10.5 kΩ
(2)
Recommended Values:
I
LED
(mA)
300
350
450
R
IADJ
(Ω)
499
short
short
R
VREF
(Ω)
open
open
10.5k
Maximum Switch Current Limit
The LED Driver Module features an integrated switch current limiting mechanism to prevent the LEDs from being
overdriven. The switch current limiter is triggered when the switch current is three times exceeding the current level
set by resistor. Once the current limiter is triggered, the internal power switch turn OFF for 3.6 μs to discharge the
inductor until inductor current reduces back to normal level. The current limiting feature is exceptionally important to
avoid permanent damage of the LED driver module application circuit due to short circuit of LED string.
1.
2.
3.
4.
5.