PSC-Family
Switching Regulators, PCB & Chassis
Rugged Environment
PSR: Positive Switching Regulators
No input to output isolation
Single output of 12, 15, 24, 36 or 48 V DC/72...288 W
Input voltage up to 144 V DC
•
High efficiency up to 96%
•
Extremely wide input voltage range
•
Very good dynamic properties
•
Input undervoltage cut-out
•
External output voltage adjustment and inhibit
•
Two temperature ranges
•
Continuous no-load and short-circuit proof
•
No derating
Safety according to IEC 950
C
PSC-Family
4.1
Table of Contents
Page
Type Survey .............................................................. 4 - 22
Description ................................................................ 4 - 22
Safety and Installation Instructions ........................... 4 - 23
Standard Features .................................................... 4 - 24
Immunity to Environmental Conditions ...................... 4 - 25
Electromagnetic Compatibility EMC .......................... 4 - 26
Characteristics and Definitions .................................. 4 - 27
Electrical Input and Output Data ............................... 4 - 28
Description of Options ............................................... 4 - 30
Mechanical Data ....................................................... 4 - 32
Type Key and Product Marking ................................. 4 - 32
Type Survey
Table 1: Type survey
Nominal
output
voltage
U
o nom
12 V
15 V
24 V
36 V
48 V
1
Nominal
output
current
I
o nom
6A
Input
voltage
range
U
i 1
18...144 V
22...144 V
31...144 V
44...144 V
58...144 V
Nominal
input
voltage
U
i nom
60 V
Efficiency
Type
designation
Options
η
89%
90%
94%
PSC 126-7iR
PSC 156-7iR
PSC 246-7iR
PSC 366-7iR
PSC 486-7iR
-9, L, P, C, D
80 V
95%
96%
Surges up to 156 V for 2 sec. See data
∆
U
io min
(min. differential voltage
U
i
–
U
o
)
Description
The PSC family of positive swiching regulators is designed
as power supply modules for electronic systems. Their ma-
jor advantages include a high level of efficiency that re-
mains virtually constant over the entire input range, high
reliability, low ripple and excellent dynamic response.
Modules with input up to 144 V are specially designed for
battery driven mobile applications.
Case C03: Aluminium, black finish and self cooling.
External input circuitry
An external capacitor (see "Application Notes") is required
in rectifier mode and in DC operation mode only, if the sum
of the lengths of the two input lines between source and in-
put (without option L) is greater than approx. 5 m. For long
connection lines the use of option L is recommended in or-
der to reduce superimposed interference voltages or cur-
rents and to prevent oscillation.
4 - 22
MELCHER
The Power Partners.
Edition 2/96 - © Melcher AG
Rugged Environment
I
i
Switching Regulators, PCB & Chassis
PSC-Family
I
o
Vi+
Input
Filter
L (option)
Vo+
i
Control circuit
C (option)
R
G
U
i
C
e
U
o
Gi–
Go–
Safety and Installation Instructions
Safety
If the output circuit of a switching regulator is operator-ac-
cessible according to the IEC 950 related safety standards,
it shall be an SELV circuit (Safety Extra Low Voltage circuit,
i.e. a circuit, separated from mains by at least basic insula-
tion, that is so designed and protected that under normal
and single fault conditions, the voltage between any two
conductors and between any conductor and earth does not
exceed 60 V DC).
In the following section an interpretation is provided of the
IEC 950 safety standard with respect to the safety status of
the output circuit. However, it is the sole responsibility of the
installer or user to assure the compliance with the relevant
and applicable safety standards.
If the following table is observed, the output of any switch-
ing regulator is considered to be an SELV circuit up to a
nominal output voltage of 36 V, or up to 48 V if option C is
fitted.
Note:
Check for hazardous voltages before altering
any connections. Do not open the module. The input
and the output circuitry are not separated, i.e. the nega-
tive path is internally interconnected!
Table 2: Insulation concept for SELV circuits
Nominal
mains
supply
voltage
(AC)
None
Minimum required grade
of isolation, to be
provided by the AC-DC
front end, including mains
supplied battery charger
Battery supply completely
separated from mains
Maximum
output
voltage
from the
front end
≤60
V
≤144
V
Minimum required
safety status of the
front end output circuit
Measures to achieve the
specified safety status
of the output circuit
Resulting safety
status of the
switching
regulator output
circuit
SELV circuit
SELV battery circuit
Hazardous voltage battery
circuit
2
Hazardous voltage battery
circuit
None
Input fuse
1
and unearthed,
SELV circuit
non operator-accessible case
2
Input fuse
1
and earthed output Earthed SELV
circuit
3
and earthed
3
or non
circuit
operator-accessible case
Earthed input circuit
3
Input fuse
1
and
earthed output circuit
3
SELV circuit
Earthed SELV
circuit
≤250
V
Basic
≤60
V
Earthed SELV circuit
ELV circuit
≤144
V
Hazardous voltage
secondary circuit
SELV circuit
Input fuse
1
and earthed output Earthed SELV
circuit
3
and earthed
3
or non
circuit
operator-accessible case
None
SELV circuit
Double or reinforced
≤60
V
≤144
V
Double or reinforced insu- Input fuse
1
and unearthed and SELV circuit
lated unearthed hazardous non operator-accessible case
2
voltage secondary circuit
2
The installer shall provide an approved fuse (slow blow type with lowest rating suitable for the application, max. 12.5 A) in the positive
or negative input conductor directly at the input of the switching regulator. For UL's purpose, the fuse needs to be UL-listed. If option C
is fitted, a suitable fuse is built-in.
2
Has to be insulated from earth by double or reinforced insulation according to the relevant safety standard, based on the maximum in-
put voltage of the switching regulator.
3
The earth connection has to be provided by the installer according to the relevant safety standards, e.g. IEC 950.
Edition 2/96 - © Melcher AG
1
MELCHER
The Power Partners.
4 - 23
4.1
Fig. 1
Block diagram
D (option)
P (option)
PSC-Family
Switching Regulators, PCB & Chassis
Rugged Environment
Standards and Approvals
All Melcher power supplies are subject to manufacturing
surveillance in accordance with ISO 9001 standards.
All units are UL recognized as per UL 1950, UL 1012 and
CAN/CSA C22.2 No. 234-M90. SEV approval according to
SEV 1061.1981, SEV 1085.1983 and EN 55014 standards
are in progress.
Cleaning Agents
In order to avoid possible damage, any penetration of
cleaning fluids is to be prevented, since the power supplies
are not hermetically sealed.
Protection Degree
The protection degree is defined by IP 20.
Standard Features
i Inhibit
Note:
With open i-input, output is enabled (U
o
= on)
The inhibit input allows the switching regulators to be disa-
bled via a control signal. In systems with several units, this
feature can be used, for example, to control the activation
sequence of the regulators by a logic signal (TTL, C-MOS,
etc.).
An output voltage overshoot will not occur when the units
are switched on or off.
4.1
Vi+
Vo+
i
I
inh
U
inh
Gi–
Go–
Fig. 2
Definition of I
inh
and U
inh
I
inh
[mA]
U
inh
= 0.8 V
U
o
on
U
inh
= 2.4 V
5
4
U
o
/U
o nom
1
0.1
0
U
inh
1
0
t
r
t
f
t
3
2
1
U
o
off
U
inh
[V]
t
Fig. 3
Output response as a function of inhibit signal
Data
0
-50 -40 -30 -20 -10
0
10
20
30
40
50
Fig. 4
Inhibit current I
inh
versus inhibit voltage U
inh
Table 3: Inhibit characteristics
Characteristics
Conditions
min
–50
+2.4
5
10
10
mA
typ
max
+0.8
+50
ms
Unit
V DC
U
inh
Inhibit input voltage to keep
regulator output voltage...
U
o
= on
U
o
= off
U
i min
...U
i max
T
C min
...T
C max
U
i
=
U
i nom
R
L
=
U
o nom
/I
o nom
I
o
= 0,
U
i
=
U
i nom
t
r
t
f
I
i off
Switch-on time after inhibit command
Switch-off time after inhibit command
Input current when inhibited
4 - 24
MELCHER
The Power Partners.
Edition 2/96 - © Melcher AG
Rugged Environment
Switching Regulators, PCB & Chassis
Vo +
PSC-Family
R External Output Voltage Adjustment
Note:
With open R input,
U
o
=
U
o nom
.
R-input and option P cannot be supported simultaneously.
The output voltage
U
o
can either be adjusted with an exter-
nal resistor (R
1
or
R
2
) or with an external voltage (U
ex
). The
adjustment range is 0...1.08 of
U
o nom
. The minimal differen-
tial voltage
∆
U
io min
between input and output should be
maintained (see data). Min. input = Undervoltage cut-out.
Vo +
R
2
U
ref
4000
Ω
R
+
–
R
1
G
Go –
Fig. 6
Voltage adjustment with external resistor R
1
or R
2
[
Ω
]
b)
U
o
= 0...100 %
U
o nom
, using
R
1
between R and G (Go-):
U
ref
4000
Ω
R
+
+
–
U
ex
G
R
1
U
o
≈
U
o nom
• ––––––––
R
1
+ 4000
4000 •
U
o
R
1
≈
–––-––––
U
o nom
-
U
o
4.1
Go –
c)
U
o
=
U
o nom
...
U
o max
, using
R
2
between R and Vo+:
U
o max
=
U
o nom
+ 8%
Fig. 5
Voltage adjustment with U
ex
[V] between R and G (Go-):
U
o nom
a)
U
o
≈
U
ex
• ––––––
(U
ref
= 2.5 V
±2
%)
U
ref
Caution:
To prevent damage
U
ex
should not exceed
20 V, nor be negative.
R
2
U
o
≈
U
ref
• ––––––––––––––––––
k • (R
2
+ 4000) – 4000
U
o
• (1 – k)
R
2
≈
4000 • –––––––––
k •
U
o
–
U
ref
U
ref
k = ––––––
U
o nom
(U
ref
= 2.5 V
±2
%)
All formulae give approximate values only.
Immunity to Environmental Conditions
Table 4: Mechanical stress
Test Method
Ca
Damp heat
steady state
Shock
(half-sinusoidal)
Continuous shock
(half-sinusoidal)
Vibration
(sinusoidal)
Standard
DIN 40046 part
IEC 68-2-3
MIL-STD-810D section 507.2
DIN 40046 part 7
IEC 68-2-27
MIL-STD-810D section 516.3
DIN 40046 part 26
IEC 68-2-29
MIL-STD-810D section 516.3
DIN 40046 part 8
IEC 68-2-6
MIL-STD-810D section 514.3
Test Conditions
Temperature:
Relative humidity:
Duration:
Acceleration amplitude:
Bump duration:
Number of bumps:
Acceleration amplitude:
Bump duration:
Number of bumps:
Frequency (1 Oct/min):
Max. vibration amplitude:
Acceleration amplitude:
Test duration:
Acceleration spectral density:
Frequency band:
Acceleration magnitude:
Test duration:
Concentration:
Duration:
Storage:
Storage duration:
Number of cycles:
40
±2
°C
93
+2/-3
%
56 days
100 g
n
= 981 m/s
2
6 ms
18 (3 each direction)
40 g
n
= 392 m/s
2
6 ms
6000 (1000 each direction)
10...2000 Hz
0.35 mm (10...60 Hz)
5 g
n
= 49 m/s
2
(60...2000 Hz)
7.5 h (2.5 h each axis)
0.05 g
2
/Hz
20...500 Hz
4.9 g
rms
3 h (1 h each axis)
5% (30°C)
2 h per cycle
40°C, 93 % rel. humidity
22 h per cycle
3
Status
Unit not
operating
Unit
operating
Unit
operating
Unit
operating
Ea
Eb
Fc
Fda
Random vibration DIN 40046 part 23
wide band
IEC 68-2-35
reproducibility high
Salt mist
cyclic
(sodium chloride
NaCl solution)
DIN 40046 part 105
IEC 68-2-52
Unit not
operating
Kb
Unit not
operating
Table 5: Temperature specifications, valid for air pressure of 800...1200 hPa (800...1200 mbar)
Temperature
Characteristics
Conditions
Standard -7
min
–25
–25
–40
max
71
95
100
min
–40
–40
–55
Option -9
max
71
95
100
Unit
°C
T
A
T
C
T
S
1
Ambient temperature
1
Case temperature
Storage temperature
1
U
i min
...U
i max
I
o
= 0...I
o nom
Not operational
MIL-STD-810D section 501.2 and 502.2
Edition 2/96 - © Melcher AG
MELCHER
The Power Partners.
4 - 25
PSC-Family
Table 6: MTBF and device hours
MTBF
MTBF acc. to MIL-HDBK-217F
1
Switching Regulators, PCB & Chassis
Rugged Environment
Ground Benign
Ground Fixed
Ground Mobile
Device Hours
1
2'800'000 h
T
C
= 40
°C
660'000
T
C
= 40°C
143'000 h
T
C
= 70°C
81'000 h
T
C
= 50°C
68'000 h
Statistical values, based on an average of 4300 working hours per year and in general field use
Electromagnetic Compatibility EMC
Immunity
General condition: Case not earthed.
4.1
Table 7: Immunity type tests
Phenomenon
Standard
Class
Level
III
Coupling
mode
4
i/o, i/c, o/c
+i/–i
i/o, i/c, o/c
+i/–i
i/c, +i/–i
Value
applied
5000 V
p
Waveform
1.2/50
µs
Source
Imped.
500
Ω
Test
procedure
3 pos. and 3 neg.
impulses per
coupling mode
2 s per
coupling mode
In Per-
oper. form.
no
-
Impulse voltage
IEC 255-4
App. E4
5
(1976)
IEC 255-4
App. E5
5
(1976)
IEC 571-1
(1990-07)
High frequency
disturbance
Voltage surge
III
2500 V
p
1000 V
p
800 V
p
1500 V
p
400 damped
1 MHz waves/s
100
µs
50
µs
200
Ω
yes
1
100
Ω
1 pos. and 1 neg.
voltage surge per
coupling mode
yes
2
3000 V
p
4000 V
p
7000 V
p
Electrostatic
discharge
Electric field
Fast transient/
burst
IEC 801-2
(1991-04)
IEC 801-3
(1984)
IEC 801-4
(1988)
4
contact discharge
to case
antenna in
1m distance
i/c, +i/–i
8000 V
p
5
µs
1
µs
100 ns
1/50 ns
330
Ω
10 positive and
10 negative
discharges
26…1000 MHz
50
Ω
1 min positive
1 min negative
bursts per
coupling mode
yes
1 3 6
3
4
10 V/m
sine wave mod-
ulated w. 1 kHz
yes
yes
1
4000 V
p
bursts of 5/50 ns
5 kHz rep. rate
transients with
15 ms burst
duration and a
300 ms period
2000 V
p
1000 V
p
10 V
rms 7
80% amplitude
modulated
with 1 kHz
1.2/50
µs
1 3 6
Transient
IEC 801-5
(Draft 1993-01)
IEC 801-6
III
i/c
+i/–i
12
Ω
2
Ω
50
Ω
5 pos. and 5 neg.
impulses per
coupling mode
AM 0.15...80 MHz
yes
1 6
Immunity to
conducted
disturbancies
1
2
3
4
5
6
7
3
i, o, signal wires
yes
1
Normal operation, no deviation from specifications
Normal operation, temporary deviation from specs possible
With option C: manual reset
i = input, o = output, c = case
In correspondance with DIN 57435 part 303 and VDE 0435 part 303 (1984-09)
Option L neccessary
Open circuit
Emission
For emission levels refer to "Electrical Input and Output
Data".
4 - 26
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Edition 2/96 - © Melcher AG
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