Datasheet

we-online.com
© May 2016
Würth Elektronik eiSos GmbH & Co. KG - Data Sheet - REV 1.0
30/46
WPMDU1251501 / 171021501
MagI³C Power Module
VDRM - Variable Step Down Regulator Module
Light Load Operation
The MagI³C Power Module is a non-synchronous converter. One of its characteristics is, that as the load current on the
output is decreased a point is reached where the energy delivered by a single switching pulse is more than the load can
absorb. This causes the output voltage to rise slightly. This rise in output voltage is sensed by the feedback loop and the
device responds by skipping one or more switching cycles until the output voltages falls back to the set point. At very light
loads or no load, many switching cycles are skipped. The observed effect during this pulse skipping mode of operation is
an increase in the peak to peak ripple voltage, and a decrease in the ripple frequency. The load current at which pulse
skipping begins is a function of the input voltage, the output voltage, and the switching frequency. A plot of the pulse
skipping threshold current as a function of input voltage is given in Figure 13 for a number of popular output voltage and
switching frequency combinations.
27D
Output Current (mA)
Input Voltage (V)
0
100
200
300
400
500
600
700
800
900
10 15 20 25 30 35 40 45 50
2.5V/400kHz
3.3V/400kHz
5.0V/400kHz
9V/600kHz
12V/800kHz
15V/1MHz
Figure 13. Pulse Skipping Load Threshold