WPMDH1100601 / 171010601
MagI3C Power Module
VDRM – Variable Step Down Regulator Module
All considerations mentioned above are summarized in the diagram below. The curves depict the relation between the
switching frequency and the RON for some typical output voltages. For the switching frequency, only the range indicated in
the “ELECTRICAL SPECIFICATIONS” section on page 5 (from 200kHz to 800kHz) is considered. Due to the minimum on-
time previously mentioned, under low duty cycle conditions, there are some limitations in the minimum selectable RON
.
These limits are shown below with a dotted line and they refer to some typical input voltages (24V, 36V and the maximum
operating voltage of 42V).
As stated above, the off-time is also limited to a minimum value of 260 ns, which limits the maximum duty cycle. Larger RON
(lower FSW) should be selected in any application requiring large duty ratio.
The choice of the switching frequency influences the efficiency of the system, especially at low currents, as the picture below
depicts.
Efficiency vs Frequency, VIN = 12V, VOUT = 5V, TA = 25°C
100
95
90
85
80
75
70
65
fsw = 200kHz
60
fsw = 500kHz
55
fsw = 800kHz
50
0
0,2
0,4
0,6
0,8
1
Output Current [A]
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Würth Elektronik eiSos GmbH & Co. KG – Data Sheet Rev. 1.0
© September 2017
19/54
WURTH [ WURTH ELEKTRONIK GMBH & CO. KG, GERMANY. ]
