Cassette Style
150 Watt DC-DC Converters
K Series
Edition 01/01.2000
4/31
Fig. 1
Block diagram of single output converters AK…EK 1000
Input
filter
Control
circuit
2
P
3
Forward
converter
(approx.
120
kHz)
Y
16
18
20
22
12
4
6
8
10
14
Y
Output
filter
1
26
28
30
32
24
4
–
+
Y
Vi+
Vi–
R
i
D/V
T
03057
S+
Vo+
Vo–
S–
Functional Description
The input voltage is fed via an input fuse, an input filter, and
an inrush current limiter to the input capacitor. This capaci-
tor sources a single transistor forward converter. Each out-
put is powered by a separate secondary winding of the
main transformer. The resultant voltages are rectified and
their ripples smoothed by a power choke and output filter.
The control logic senses the main output voltage
Uo1 and
generates, with respect to the maximum admissible output
currents, the control signal for the primary switching tran-
sistor.
The second output of double output units is controlled by
the main output but has independent current limiting. If the
main output is driven into current limitation, the second out-
put voltage will fall as well and vice versa.
Fig. 2
Block diagram of symmetrical double output converters AK...EK 2000
1 Transient suppressor (VDR) in CK, DK, EK, FK types
2 Transient suppressor (diode) in AK, BK, CK, FK types
3 Inrush current limiter in CK, DK, EK types (NTC or Opt. E), -9 versions exclude the NTC
4 Input fuse
Input
filter
Control
circuit
1
2
P
3
Forward
converter
(approx.
110
kHz)
16
18
20
22
12
14
4
6
8
10
Output
2
filter
Output
1
filter
26
28
30
32
24
4
–
+
Y
R
i
D
T
Vi+
Vi–
03058
Vo1+
Vo1–
Vo2+
Vo2–