Data Sheet

WPMDH1152401 / 171012402
MagI
3
C Power Module
VDRM – Variable Step Down Regulator Module
we-online.com Würth Elektronik eiSos GmbH & Co. KG – Data Sheet Rev. 2.0
© December 2017
19/54
All considerations mentioned above are summarized in the diagram below. The curves depict the relation between the
switching frequency and the R
ON
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.
As stated above, the off-time is also limited to a minimum value of 260 ns, which limits the maximum duty cycle. Larger R
ON
(lower F
SW
) 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.
0
100
200
300
400
500
600
700
800
900
1000
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950
Switching frequency [kHz]
R
ON
[kΩ]
Vout = 24V
Vout = 18V
Vout = 15V
Vout = 12V
Vout = 5V
switching frequency
allowed range
50
55
60
65
70
75
80
85
90
95
100
0 0,25 0,5 0,75 1 1,25 1,5 1,75 2
Efficiency [%]
Output Current [A]
Efficiency vs Frequency, V
IN
= 24V, V
OUT
= 12V, T
A
= 25°C
fsw = 200kHz
fsw = 500 kHz
fsw = 800 kHz