
Cassette Style
DC-DC Converters
M Series
Edition 01/01.2001
4/25
Functional Description
The input voltage is fed via an input fuse, an input filter, a
rectifier 3 and an inrush current limiter 4 to the input capaci-
tor. This capacitor sources a single transistor forward con-
verter. Each output 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
an output filter. The control logic senses the main output
voltage
Uo1
admissible output currents, the control signal for the pri-
mary switching transistor. This signal is fed back via a cou-
pling transformer.
The auxiliary outputs
Uo2 and Uo3 are individually regulated
by means of secondary switching transistors. Each aux-
iliary output's current is sensed using a current transformer.
If one of the outputs is driven into current limit, the other out-
puts will reduce their output voltages as well because all
output currents are controlled by the same main control cir-
cuit.
Fig. 1b
Block diagram, class II equipment (double insulation)
1 Transient suppressor diode in AM, BM, CM, FM and CMZ types.
2 Bridge rectifier in LM and LMZ, series diode in EM types.
3 Inrush current limiter (NTC) in CM, DM, EM, LM and CMZ, DMZ, LMZ types (option E: refer to the description of option E).
4 Single output modules AM...LM 1000 and CMZ...LMZ 1000 with feature R.
For output configuration please refer to table:
Pin allocation.
Fig. 1a
Block diagram, class I equipment
Input
filter
Output 1
filter
Output 3
filter
Output 2
filter
Control
circuit
Main control circuit
Control
circuit
1
Fuse
P
29
11
8
23
5
26
32
17
14
20
2
14
17
3
2
Forward
converter
approx.
70
kHz
4
CY
CMKT
Vi+
Vi–
i
D/V
R
G
03009
Input
filter
Output 1
filter
Output 3
filter
Output 2
filter
Control
circuit
Main control circuit
Control
circuit
1
Fuse
P
29
11
8
23
5
32
17
14
20
2
14
17
3
2
Forward
converter
approx.
70
kHz
4
CMKT
Vi+
Vi–
i
D/V
R
G
CY
03010