Datasheet

WPMDB1400362Q / 171040302
MagI
3
C Power Module
VDRM – Variable Step Down Regulator Module
we-online.com Würth Elektronik eiSos GmbH & Co. KG – Data Sheet Rev. 1.0
© May 2016 27/48
Step 5 Select soft-start capacitor (C
SS
)
Connecting the INTSS pin to AGND and leaving SS/TRK pin open enables the internal soft-start capacitor with a soft-start
interval of approximately 1 ms. Adding additional capacitance between the SS/TRK pin and AGND increases the soft-start
time according to the table below. There is no maximum value limit for C
SS
.
SS/TRK
INTSS
C
SS
7
6
AGND
VOUT
C
O UT
V
OUT
C
SS
[nF] Open 2.2 4.7 10 15 22 27
Soft-start [ms] ~1 ~2 ~3 ~4 ~6 ~9 ~10
The values in the table have been measured at room temperature under full load condition and gives an indication of the
soft-start duration.
The diagram below illustrates how the slope of the output voltage changes according to the different soft-start settings. It is
important to highlight that the implementation of the soft-start (also without the external C
SS
, a default soft-start capacitor is
internally present) prevents the output voltage from experiencing overshoots.
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
0 2 4 6 8 10
Output voltage [V]
Time [ms]
Output voltage at start up with different soft-start capacitors - V
IN
= 5V
without Css
Css = 2.2nF
Css = 4.7nF