Cassette Style
AC-DC Converters
M Series
Edition 5/5.2000
4/24
Functional Description
The input voltage is fed via an input fuse, an input filter, a
rectifier and an inrush current limiter to the input capacitor.
This capacitor sources a single transistor forward converter.
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
and generates, with respect to the maximum admissible
output currents, the control signal for the primary switching
transistor. This signal is fed back via a coupling transformer.
Fig. 1a
Block diagram, class I equipment
The auxiliary outputs
Uo2 and Uo3 are individually regulated
by means of secondary switching transistors. Each auxili-
ary 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 Inrush current limiter (option E: refer to the description of
option E)
2 Single output modules LM 1000 and LMZ 1000 with feature R
Input
filter
Output 1
filter
Output 3
filter
Output 2
filter
Control
circuit
Main control circuit
Control
circuit
Fuse
P (option)
29
11
8
23
5
32
17
14
20
2
14
17
1
Forward
converter
approx.
70
kHz
2
VDR
NTC
P
N
i
D/V
R
G
CY
CMKT
03082
Input
filter
Output 1
filter
Output 3
filter
Output 2
filter
Control
circuit
Main control circuit
Control
circuit
Fuse
P (option)
11
CMKT
8
23
5
17
14
20
2
14
17
1
Forward
converter
approx.
70
kHz
2
CY
VDR
NTC
P
N
29
32
26
CY
CMKT
03081
i
D/V
R
G