Industrial Environment
DC-DC Converters <40 Watt
SR Series
20 Watt DC-DC Converters
Single output of 5, 12, 15 or 24 V DC
Input voltage up to 180 V DC
•
Full input to output isolation 2.5 kV
rms
•
Wide input voltage range
•
High efficiency up to 81%
•
Efficient input filter
•
Very good dynamic characteristics
•
Parallel and series compatible
•
Continuous no-load and short circuit proof
Safety according to IEC/EN 60950
LGA
SR Series
32
1.3"
88
3.5"
151
5.9"
Summary
The DC-DC converters of the SR series are power supply
modules for electronic systems. Their major advantages in-
clude a high efficiency that remains virtually constant over
the entire input voltage range, high reliability, low ripple and
excellent dynamic response. The converters are designed
for chassis mounting.
Type Survey and Key Data
Table 1: Type survey
Output voltage
U
o nom
I
o nom
[V DC]
[A]
5
12
15
24
1
2
U
i min
...U
i max
19...45 V DC
1
BSR 2005-7
BSR 2012-7
BSR 2015-7
BSR 2024-7
Input voltage range and efficiency
2
h
min
h
typ
U
i min
...U
i max
h
min
h
typ
1
[%] [%]
38...90 V DC
[%] [%]
70
74
74
75
73
77
78
79
CSR 2005-7
CSR 2012-7
CSR 2015-7
CSR 2024-7
74
75
76
77
77
78
79
81
Options
U
i min
...U
i max
76...180 V DC
DSR 2005-7
DSR 2012-7
DSR 2015-7
DSR 2024-7
h
min
h
typ
[%] [%]
74
75
76
77
77
78
79
81
-6, R
1
, i, P
4
1.67
1.34
0.84
With option R, shifted input voltage range, for BSR: 16...38 V DC, for CSR: 32...76 V DC. Not available for DSR.
Efficiency at
U
i nom
and
I
o nom
.
Table of Contents
Page
Page
Electrical Output Data ...................................................... 5
Immunity to Environmental Conditions ............................. 6
Mechanical Data .............................................................. 7
Safety and Installation Instructions .................................. 8
Description of Options .................................................... 10
Summary .......................................................................... 1
Type Survey and Key Data .............................................. 1
Type Key and Product Marking ........................................ 2
Functional Description ...................................................... 3
Electrical Input Data ......................................................... 4
MELCHER
The Power Partners.
Edition 4/6.99
1/11
SR Series
DC-DC Converters <40 Watt
Industrial Environment
Type Key and Product Marking
Type Key
B SR 20 05 -7 R i P
Input voltage range
U
i
19...45 V DC ............................................... B
38...90 V DC .............................................. C
76...180 V DC .............................................. D
Series ............................................................................ SR
Nominal output power in watt ......................................... 20
Nominal output voltage in volt
5 V ........................................................... 05
12 V ........................................................... 12
15 V ........................................................... 15
24 V ........................................................... 24
Ambient temperature range
T
A
= –25...71°C:
Plastic semi-conductors .............................. -7
Hermetic semi-conductors (option) ............. -6
Options:
Shifted input voltage range ......................... R
Inhibit input ................................................... i
Potentiometer .............................................. P
BSR 2005-7RiP = 20 Watt DC-DC converter with a 5 V output, ambient temperature range of –25...71°C,
shifted input range of
U
i
= 16...38 V DC, inhibit, and potentiometer.
Example:
Produkt Marking
Basic type designation, applicable safety approval and recognition marks, CE mark, warnings and Melcher company logo.
Specific type designation, input voltage range, nominal output voltage and current, pin allocation, identification of LED and
potentiometer.
Label with batch No., serial No. and data code comprising production site, modification status of the main PCB and date of
production.
MELCHER
The Power Partners.
Edition 4/6.99
2/11
Industrial Environment
Functional Description
DC-DC Converters <40 Watt
SR Series
After passing through a line interference filter, the DC volt-
age is chopped at a constant frequency of about 30 kHz.
After transformer isolation and rectification, an output filter
reduces ripple to a minimum without compromising the dy-
namic behaviour. The output voltage is routed to a control
circuit with internal sense lines, where the output voltage is
compared with a reference voltage. The voltage is regulated
via a control transformer by varying the duty ratio of the for-
ward converter.
The converters have input transient protection by means of
a zinc oxide VDR and input reverse polarity protection by
means of a protective diode and a fuse.
An internal inhibit signal keeps the output voltage switched
off below approx. 0.7...0.9
U
i min
.
The outputs are protected against continuous open circuit
by means of an internal, electronically switched pre-load
and against continuous short circuit by the current limiting
circuit.
No output voltage overshoot will occur when plugging in or
disconnecting the module, switching the input voltage on/
off, inhibiting the unit or after reset.
In the event of a main control circuit failure, the maximum
output voltage
U
o
is restricted to approx. 1.2
U
o nom
by
means of an independent second control circuit.
When the converters are located in free, stationary air at
a temperature
T
A max
= 71°C and are operated at nominal
power, the case temperature
T
C max
will reach approx. 85°C
after a certain warm-up time (Case temperature
T
C
at the
measuring point, see:
Mechanical Data).
Under certain operating conditions the ambient tempera-
ture
T
A max
may be allowed to exceed 71°C provided that
additional measures are taken to ensure the case tempera-
ture
T
C max
remains below 85°C.
P (option)
03051
i (option)
Control circuit
+
Input
Filter
–
Forward
converter
30 kHz
+
–
2.2 nF
2.2 nF
4.7 nF
( )
Fig. 1
Block diagram
MELCHER
The Power Partners.
Edition 4/6.99
3/11
SR Series
Electrical Input Data
General Conditions
–
T
A
= 25°C, unless
T
C
is specified
– With option i, pin i is connected with –
U
o
– With option P,
U
o
=
U
o nom
at
I
o nom
DC-DC Converters <40 Watt
Industrial Environment
Table 2: Input data
Input
Characteristics
Conditions
Standard
Option R
min
19
16
BSR
typ
(30)
(24)
28
0.2
1
EN 55022
50
Ω/50 µH
U
i
=
U
i nom
slow blow
1.2/5
µs
VDE 0433
0.8
1...6
1
3.15
1.5
1...4
1
B
max
45
38
min
38
32
CSR
typ
(60)
(48)
22
0.3
0.7
B
max
90
76
min
76
DSR
typ
(120)
n.a.
10
0.4
1
B
A
ms
max
180
Unit
V DC
U
i
Input
(U
i nom
) voltage
I
inr p
t
inr r
t
inr h
u
i RFI
I
o
= 0...I
o nom
T
C min
...T
C max
U
i nom
Peak inrush current
Rise time
Time to half-value
RFI level at input
0.01...30 MHz
Primary fuse rating
Input transient
suppression
Si
u
i tr
I
i inh
I
i uv
2
2.5
1.6
A
kV
Residual input current 5 min. after
with converter inhibited start
Input current
undervoltage lock-out
after 5 min.
U
i
< 0.7
U
i min
1...4
1
mA
I
i
[A]
1.75
1.50
1.25
1.00
0.75
0.50
0.25
0
15
I
i
[mA]
U
i min
= 19 V DC
BSR 20
03052
1000
800
U
i min
= 38 V DC
03053
CSR 20
I
o
=
I
o nom
600
I
o
=
I
o nom
400
I
o
=
1
/
2 o nom
200
I
o
= 0
20
25
30
35
40
45
U
i
[V]
I
o
=
1
/
2
I
o nom
I
o
= 0
0
30
40
50
60
70
80
90
U
i
[V]
Fig. 2
Input current I
i
versus input voltage U
i
I
i
[mA]
500
400
300
I
o
=
I
o nom
200
100
0
60
I
o
=
1
/
2
I
o nom
I
o
= 0
80
100
120
140
160
180
U
i
[V]
U
i min
= 76 V DC
03054
Fig. 3
Input current I
i
versus input voltage U
i
I
i
[A]
1.0
0.8
0.6
0.4
0.2
0
1
03055
DSR 20
I
o nom
U
i
= 30 V DC (BSR)
U
i
= 60 V DC (CSR)
U
i
= 120 V DC (DSR)
1
1
1
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
I
o
/I
o nom
Switch-off point of internal pre-load
Fig. 4
Input current I
i
versus input voltage U
i
Fig. 5
Input current I
i
versus input voltage U
i
MELCHER
The Power Partners.
Edition 4/6.99
4/11
I
o L
Industrial Environment
Electrical Output Data
General Conditions
–
T
A
= 25°C, unless
T
C
is specified
– With option i, pin i is connected with –
U
o
– With option P,
U
o
=
U
o nom
at
I
o nom
DC-DC Converters <40 Watt
SR Series
Table 3: Output data
Output
Characteristics
Conditions
..SR 2005..
min typ max
4.97
0
4.8
5.3
30
6.8
40
13.5
10
5.03
4
SR 2012 ..
min typ max
11.92
0
1.84
16.0
20
16.5
10
12.07
1.67
SR 2015 ..
min
14.91
0
1.47
19.0
20
27.0
10
typ max
15.09
1.34
SR 2024
min
23.85
0
0.92
31.0
20
V DC
mV
pp
mV
typ max
24.14
0.84
Unit
V DC
A
U
o
I
o
I
o L
U
o L
u
o
Output voltage
Output current
Output current limitation
Overvoltage limit with
second control loop
Total output voltage
noise (BW = 20 MHz)
1
U
i nom
,
I
o nom
U
i min
...U
i max
U
i min
...U
i max
T
C min
...T
C max
Failure of main
control circuit
U
i min
...U
i max
I
o nom
U
i nom
I
o
= 0...I
o nom
D
U
o U
Static line regulation
D
U
o I
Static load regulation
Dynamic
load re-
gulation
±12 ±24
12
±70
70
±1
±0.02
25
±10 ±20
20
±25
150
±2
±0.02
40
±10 ±20
25
±25
200
±3
±0.02
50
±12 ±25
30
±25
300
±5
±0.02
60
u
o d
t
d
a
Uo
Voltage deviat.
U
i nom
1
↔
1
/
5
I
o nom
Recovery time
IEC/EN 61204
µs
mV/K
%/K
Temperature coefficient
D
U
o
/DT
C
U
i min
...U
i max
I
o
= 0...I
o nom
1
2
According to IEC/EN 61204. See:
Technical Information: Measuring and Testing.
See:
Dynamic Characteristics.
∆U
o I
[mV]
U
o
05010
u
od
D
U
o I
D
U
o I
40
1
05066
2024
2015
1
30
t
d
I
o
/I
o nom
1
u
od
t
d
t
1
20
10
0
1
2012
2005
0
≥10
s
≥10
s
t
–10
1
Fig. 6
Dynamic load regulation.
U
o
/U
o nom
I
o nom
I
o L
0.5
0
0.25
Switch-off point of internal pre-load
0.75
1.0
I
o
/I
o nom
1.2
1.0
0.8
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
05067
Fig. 7
Static load regulation.
Output voltage U
o
versus output current I
o
.
1.0
1.2
1.4
I
o
/I
o nom
Fig. 8
Short-circuit behaviour.
Output voltage U
o
versus output current I
o
.
MELCHER
The Power Partners.
Edition 4/6.99
5/11
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