Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
1/18
35 Watt DC-DC Converters IMX 35 Series
Input to output electric strength test up to 4 kV DC
Input voltage: 9...36, 18...75 V DC
2, 3 and 4 outputs
Configurable output voltages from 3.3 to 60 V DC
• Extremely wide input voltage ranges
• Electrical isolation, also between outputs
• Emissions below EN 55022, level B
• Immunity to IEC/EN 61000-4-2,-3,-4,-5 and -6
• Programmable input undervoltage lock-out
• Shut down input
• Output voltages adjustable with flexible load distribu-
tion
• Frequency synchronisation
• Outputs no-load, overload and short-circuit proof
• Operating ambient temperature up to –40...85°C
• Thermal protection
•3" × 2,5" case with 10.5 mm profile or 8.9 mm open
frame
• Supplementary insulation
Summary
The IMX 35 series of board mountable 35 Watt DC-DC con-
verters has been designed according to the latest industry
requirements and standards. The converters are particu-
larly suitable for use in mobile or stationary applications in
transport, railways, industry, or telecommunication where
variable input voltages or high transient voltages are preva-
lent.
Covering a total input voltage range from 9 up to 75 V with
2 different types. The units are available with double, triple
and quadruple outputs, electrically isolated, from 3.3 V up
to 60 V externally adjustable and with flexible load distribu-
tion. A shut down input allows remote converter on-off. Fea-
tures include consistently high efficiency over the entire in-
put voltage range, high reliability and excellent dynamic re-
sponse to load and line changes.
The converters are designed and built according to the in-
ternational safety standards IEC/EN 60950, UL 1950, CAN/
CSA C22.2 No.950-95. LGA, UL and cUL approvals are in
progress. The IMX 35 types provide supplementary insula-
tion. Connected to a secondary circuit the 40 IMX 35 types
provide SELV outputs even if the voltage at the converter
input exceeds the SELV-limit of 60 V DC.
The circuit comprises of two planar magnetics devices and
all components are automatically assembled and solidly
soldered onto a single PCB without any wire connection.
Magnetic feedback ensures maximum reliability and
repeatability in the control loop over all operating condi-
tions. Careful considerations of possible thermal stresses
ensure the absence of hot spots providing long life in envi-
ronments where temperature cycles are a reality. The ther-
mal design without using any potting material allows opera-
tion at full load up to an ambient temperature of 71°C in free
air. For extremely high vibration environments the case has
holes for screw mounting. Various options as e.g. extended
temperature range –40...85°C or an alternative pinout pro-
vide a high level of application specific engineering and de-
sign-in flexibility.
Safety according to IEC/EN 60950, UL 1950
Approvals pending
LGA
Table of Contents Page
Summary .......................................................................... 1
Type Survey and Key Data .............................................. 2
Type Key .......................................................................... 3
Functional Description...................................................... 4
Electrical Input Data ......................................................... 6
Electrical Output Data ...................................................... 8
Page
Auxiliary Functions ......................................................... 11
Electromagnetic Compatibility (EMC) ............................ 13
Immunity to Environmental Conditions........................... 14
Mechanical Data ............................................................ 15
Safety and Installation Instructions ................................ 16
Description of Option...................................................... 18
76.2
3"
63.5
2.5"
10.5
0.41"
72.8
2.87"
47.8
1.88"
8.9
0.35"
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
2/18
Type Survey and Key Data
Table 1: Type survey
Output 1 Output 2 Output 3 Output 4 Input voltage Eff. Type Trim Opt.
U
o nom
I
o nom
U
o nom
I
o nom
U
o nom
I
o nom
U
o nom
I
o nom
U
i min...
U
i max htyp designation
[V DC] [A] [V DC] [A] [V DC] [A] [V DC] [A] [V DC] [%]
3.3 4.25 5 2.7 - - - - 9...36 83 20 IMX 35-03-05-9 second. -8
3.3 4.5 5 2.8 - - - - 18...75 40 IMX 35-03-05-9 Z
5.1 3.3 5 2.7 - - - - 9...36 84 20 IMX 35-05-05-9 second. i
5.1 3.5 5 2.8 - - - - 18...75 40 IMX 35-05-05-9
12 1.3 12 1.3 - - - - 9...36 87 20 IMX 35-1212-9 primary
12 1.4 12 1.4 - - - - 18...75 87 40 IMX 35-1212-9
15 1.1 15 1.1 - - - - 9...36 20 IMX 35-1515-9 primary
15 1.2 15 1.2 - - - - 18...75 40 IMX 35-1515-9
3.3 4.25 5 1.35 5 1.35 - - 9...36 83 20 IMX 35-03D05-9 second.
3.3 4.5 5 1.4 5 1.4 - - 18...75 40 IMX 35-03D05-9
3.3 4.25 12 0.65 12 0.65 - - 9...36 86 20 IMX 35-03D12-9
3.3 4.5 12 0.7 12 0.7 - - 18...75 40 IMX 35-03D12-9
3.3 4.25 15 0.55 15 0.55 - - 9...36 20 IMX 35-03D15-9
3.3 4.5 15 0.6 15 0.6 - - 18...75 40 IMX 35-03D15-9
5.1 3.3 5 1.35 5 1.35 - - 9...36 83 20 IMX 35-05D05-9 second.
5.1 3.5 5 1.4 5 1.4 - - 18...75 40 IMX 35-05D05-9
5.1 3.3 12 0.65 12 0.65 - - 9...36 86 20 IMX 35-05D12-9
5.1 3.5 12 0.7 12 0.7 - - 18...75 40 IMX 35-05D12-9
5.1 3.3 15 0.55 15 0.55 - - 9...36 20 IMX 35-05D15-9
5.1 3.5 15 0.6 15 0.6 - - 18...75 87 40 IMX 35-05D15-9
5 1.35 5 1.35 5 1.35 5 1.35 9...35 86 20 IMX 35 D05D05-9 primary
5 1.4 5 1.4 5 1.4 5 1.4 18...75 87 40 IMX 35 D05D05-9
12 0.65 12 0.65 12 0.65 12 0.65 9...35 87 20 IMX 35 D12D12-9 primary
12 0.7 12 0.7 12 0.7 12 0.7 18...75 89 40 IMX 35 D12D12-9
15 0.55 15 0.55 15 0.55 15 0.55 9...35 88 20 IMX 35 D15D15-9 primary
15 0.6 15 0.6 15 0.6 15 0.6 18...75 89 40 IMX 35 D15D15-9
Trim
The Trim input on the primary side influences all outputs, while Trim1 on the secondary side influences the first output (
U
o1)
only.
For the units IMX 35-12-12 and IMX 35-15-15 primary Trim (pin 5) is the Trim input influencing both outputs, while pin 18 is
not connected.
For the units IMX 35-03-05 and IMX 35-05-05, secondary Trim1 (pin 18) is the Trim1 input influencing only
U
o1, while pin 5
is not connected.
Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
3/18
Type Key
Dual output units 20 IMX 35 - 12 - 12 -9 i Z
Input voltage range
U
i
9...36 V DC ........................................... 20
18...75 V DC ........................................... 40
Series ...................................................................... IMX 35
Output 1 of double types .............................. 03, 05, 12, 15
Output 2 of double types .................................... 05, 12, 15
Operating ambient temperature range
T
A
–40...71°C (standard) ................................. -9
–40...85°C (option) ..................................... -8
Options: Inhibit ............................................................ i
Open frame .................................................. Z
Triple output units 20 IMX 35 - 05 D05 -9 i Z
Input voltage range
U
i
9...36 V DC ........................................... 20
18...75 V DC ........................................... 40
Series ...................................................................... IMX 35
Output 1 of triple types ............................................. 03, 05
Output 2 and 3 of triple types ..................... D05, D12, D15
Operating ambient temperature range
T
A
–40...71°C (standard) ................................. -9
–40...85°C (option) ..................................... -8
Options: Inhibit ............................................................ i
Open frame .................................................. Z
Quad output units 20 IMX 35 D05 D05 -9 i Z
Input voltage range
U
i
9...36 V DC ........................................... 20
18...75 V DC ........................................... 40
Series ...................................................................... IMX 35
Output 1 and 4 of quad types ..................... D05, D12, D15
Output 2 and 3 of quad types ..................... D05, D12, D15
Operating ambient temperature range
T
A
–40...71°C (standard) ................................. -9
–40...85°C (option) ..................................... -8
Options: Inhibit ............................................................ i
Open frame .................................................. Z
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
4/18
Functional Description
The IMX 35 family of DC-DC converters consists of two
feedback controlled interleaved switching flyback power
trains using current mode PWM (pulse width modulation).
Functionally the converters are of three main types. The
dual output types consist of two electrically isolated outputs
Vo1, Vo2. Vo1 and Vo2 derives from two power trains and
are electrically isolated. Voltage regulation for each output
is achieved with passive transformer feedback from the
main transformer of each power train. Adjustment of the
outputs voltages in the range of 80...105% of
U
o nom is pos-
sible via Trim input on the primary side (See:
Block dia-
gram, dual output types
.) The triple output types consist of
3 outputs Vo1, Vo2, Vo3 and two configurations. In the first
configuration Vo1 is a power train with a 5.1 V or 3.3 V out-
put and a synchronous rectifier, thus enabling high effi-
ciency. Also there is active magnetic feedback on this out-
put via a pulse transformer which results in very tight and
reliable regulation of the output voltage. The other two out-
puts Vo2 and Vo3 are electrically isolated double outputs.
Vo2, Vo3 are restricted to being of the same output voltage
(i.e. D05, D12, etc.). Voltage regulation is achieved with a
passive transformer feedback from the main transformer of
that power train.
Adjustment of the output voltages is provided for Vo1 via
the Trim1 pin referenced to the secondary side and allows
for programming of the voltage of output 1 in the range of
approx. 80...105% of
U
o nom. (See:
Block diagram, triple
output types
)
The quadruple output type consists of 4 outputs and two
power trains. Vo1, Vo4 derive from the first power train and
Vo2, Vo3 from the second one (thus each pair of outputs is
independent from the other one). Voltage regulation for
each pair of outputs is achieved with passive transformer
feedback from the main transformer of each power train.
Each pair of outputs are restricted to being of the same out-
put voltage type (i.e. D05, D12, etc.). If both power trains
have the same output voltage, all outputs may be adjusted
by means of the Trim input. (In case of different output volt-
ages, the Trim1 input influences only Vo1 and Vo4. See:
Block diagram, quadruple output types
.)
Current limitation is provided by the primary circuit for each
power train and limits the possible output power for each
pair of outputs. In the case of an overload on either of the
power trains which causes the output voltage to fall less
than typically 60% of
U
o nom, the entire converter will shut
down and automatically restart in short intervals.
Overtemperature protection is provided for each power
train which will shut down the converter in excessive over-
load conditions with automatic restart approximately in
short intervals.
PWM
4
8
1
Vi+
PUL
SD
5
Trim/n.c.
6
W
7
Ref
2
Vi–
17
15
13
11
19
Vo1+
Vo1–
Vo2+
Vo2–
n.c.
03100
3
n.c.
16 n.c.
18 Trim1/n.c.
Fig. 1
Block diagram 1, double output types
Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
5/18
PWM
4
8
1
Vi+
SD
PUL
5
Trim
6
W
7
Ref
2
Vi–
15
16
17
18
13
14
12
11
Vo4–
Vo1+
Vo1–
Vo4+
Vo2+
Vo2–
Vo3+
Vo3–
03098
2
n.c.
19
n.c.
Fig. 3
Block diagram 3, quadruple output types
PWM
4
1
1
17
15
18
Vi+
SD
PUL
Vo1+
Vo1–
Trim1
03097
5
n.c.
6
W
7
Ref
Control
2
Vi–
13
14
Vo2+
Vo2–
12
11
Vo3+
Vo3–
3
n.c.
19 n.c.
Fig. 2
Block diagram 2, triple output types
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
6/18
Electrical Input Data
General conditions:
–T
A = 25°C, unless
T
C is specified.
–Shut down pin left open circuit (not connected).
–Trim not connected.
Table 2: Input Data
Input 20 IMX 40 IMX
Characteristics Conditions min typ max min typ max Unit
U
iInput voltage range 1
T
A min...
T
A max 9 2 36 18 2 75 V DC
U
i nom Nominal input voltage
I
o = 0...
I
o nom 20 40
U
i sur Repetitive surge voltage Abs. max input (3 s) 40 100
t
start up Converter Switch on Worst case condition at 0.25 0.5 0.25 0.5 s
start-up time 2 SD high
U
i min and full load 0.1 0.1
t
rise Rise time 3
U
i nom resist load 5 5 ms
I
o nom capac. load 10 20 10 20
I
i o No load input current
I
o = 0,
U
i min...
U
i max 70 50 mA
I
irr Reflected ripple current
I
o = 0...
I
o nom 30 30
I
inr p Inrush peak current 4
U
i =
U
i nom 89A
C
iInput capacitance for surge calculation 1.5 0.75 µF
U
SD Shut down voltage Unit shut down –10...0.7 –10...0.7 V DC
Unit operating open or 2...20 open or 2...20
R
SD Shut down input resistance For current calculations approx. 10 approx. 10 kΩ
I
SD Input current if unit
U
i min...
U
i max 12 6 mA
shut down
f
sSwitching frequency
U
i min...
U
i max,
I
o = 0...
I
o nom approx. 200 approx. 200 kHz
u
i RFI Input RFI level, conducted EN 55022 5 B 6 B
1
U
i min will not be as stated if
U
o is increased above
U
o nom by use of Trim input. If the output voltage is set to a higher value,
U
i min will be proportionately increased.
2Input undervoltage lock-out at typ. 90% of
U
i min.
3Measured with resistive and max. admissible capacitive load.
4Source impedance according to prETS 300132-2, version 4.3.
5Measured with a lead length of 0.1 m, leads twisted.
6External capacitor required.
Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
7/18
Inrush current
The inrush current has been kept as low as possible by
choosing a very small input capacitance. A series resistor
may be installed in the input line to further reduce this cur-
rent.
I [A]
t [µs]
04022
010 20 30 40 50 60 70 80 90 100
4
3
2
1
Fig. 4
Typical inrush current at U
i nom
, P
o nom
versus time
(40 IMX 35). Source impedance according to
prETS 300132-2, version 4.3 at U
i nom
.
Fig. 5
Converter start-up and rise time
Uo nom
Uo
tstart up
trise
t
04008
Input Transient Voltage Protection
A built-in suppressor diode provides effective protection
against input transients which may be caused for example
by short-circuits accross the input lines where the network
inductance may cause high energy pulses.
Table 4: Built-in transient voltage suppressor
Type Breakdown Peak power Peak pulse
voltage at 1 ms current
VBr nom [V]
P
p [W]
I
pp [A]
20 IMX 35 50 1500 22
40 IMX 35 100 1500 9.7
For very high energy transients as for example to achieve
IEC/EN 61000-4-5 or ETR 283 (19 Pfl1) compliance (as per
table:
Electromagnetic Immunity
) an external inductor and
capacitor are required. The components should have simi-
lar characteristics as listed in table:
Components for exter-
nal circuitry for IEC/EN 61000-4-5, level 2 or ETR 283
(19Pfl1) compliance
.
Note: The suppressor diode D is only necessary for
20 IMX 35 types.
Table 5: Components for external circuitry for IEC/EN
61000-4-5, level 2 or ETR 283 (19Pfl1) compliance.
Type Inductor (L) Capacitor (C) Diode (D)
20 IMX 35 1.5 k E47A
40 IMX 35 -
Vi+
Vi–
C
L
D
+
04036
Fig. 6
Example for external circuitry to comply with IEC/EN
61000-4-5 or ETR 283 (19Pfl1); the diode D is only neces-
sary for 20 IMX 35 types.
Reverse Polarity Protection
The built-in suppressor diode also provides for reverse po-
larity protection at the input by conducting current in the re-
verse direction. An external fuse is required to limit this cur-
rent.
Table 3: Recommended external fuses
Converter type Fuse type
20 IMX 35 F8.0A
40 IMX 35 F4.0A
22
23.8
11.5
04052
Fig. 7
Dimensions of inductor L for 20 IMX 35 and 40 IMX 35
types (e.g. Coil Craft, PCH-45 series).
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
8/18
Electrical Output Data
General conditions:
– T
A = 25°C, unless
T
C is specified
– Shutdown pin left open circuit (not connected)
– R input not connected
Table 6a: Output data for single synchronous rectifier (main) output.
Output 3.3 V 5.1 V
Characteristics Conditions min typ max min typ max Unit
U
oOutput voltage
U
i nom,
I
o = 0.5
I
o nom 3.28 3.32 5.07 5.13 V DC
I
o nom Output current 20 IMX
U
i min...
U
i max 4.25 3.3 A
40 IMX 4.25 3.5
I
o1L Current limit 1 20 IMX
U
i nom,
T
C = 25°C 6.0 4.5
I
o2L
U
o1 = 93%
U
o nom
I
o1L 40 IMX 6.1 4.6
I
o2L
D
U
o U Line/load regulation
U
i min...
U
i max,±1±1%
I
o = (0.05...1) •
I
o nom
u
o1/2 Output voltage noise
U
i min...
U
i max 270 80 mVpp
I
o =
I
o nom 340 40
U
o L Output overvoltage limit. 4 115 130 115 130 %
C
o ext Admissible capacitive load 4000 3300 µF
u
o d Dynamic Voltage deviat.
U
i nom ±200 ±250 mV
t
dload Recovery time
I
o nom ↔ 1/2
I
o nom 11ms
regulation IEC/EN 61204
aUo Temperature coefficient
U
i min...
U
i max ±0.02 ±0.02 %/K
D
U
o/D
T
C
I
o = 0...
I
o max
Table 6b: Output data for double output power trains.
Output 2 × 5 V 2 × 12 V 2 × 15 V
Characteristics Conditions min typ max min typ max min typ max Unit
U
o1 Output voltage
U
i nom 4.95 5.05 11.88 12.12 14.85 15.15 V DC
U
o2
I
o = 0.5
I
o nom 4.94 5.06 11.86 12.14 14.82 15.18
I
o nom Output current 20 IMX
U
i min...
U
i max 2 × 1.3 2 × 0.65 2 × 0.50 A
40 IMX 2 × 1.4 2 × 0.70 2 × 0.56
I
oL Current limit 1 20 IMX
U
i nom,
T
C = 25°C 2.5 1.8 1.5
40 IMX
U
o = 93%
U
o nom 3.7 2.0 1.6
D
U
o U Line regulation
U
i min...
U
i max,
I
o nom ±1±1±1%
D
U
o l Load regulation
U
i nom ±3±3±3
I
o = (0.1...1)
I
o nom
u
o1/2 Output voltage noise
U
i min...
U
i max 280 120 150 mVpp
I
o =
I
o nom 340 60 70
U
o L Output overvoltage limit. 4 Min. load 1% 115 130 115 130 115 130 %
C
o ext Admissible capacitive load 4000 470 330 µF
u
o d Dynamic Voltage deviat.
U
i nom ±250 ±400 ±400 mV
t
dload Recovery time
I
o nom ↔ 1/2
I
o nom 111ms
regulation
aUo Temperature coefficient
U
i min...
U
i max ±0.02 ±0.02 ±0.02 %/K
D
U
o/D
T
C
I
o = 0...
I
o max
1The current limit is primary side controlled. In the event of a sustained overload condition the thermal protection may cause the unit to
shutdown (restart on cool-down).
2BW = 20 MHz
3Measured with a probe according to EN 61204
4The overvoltage protection is via a primary side second regulation loop, not tracking with Trim control.
Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
9/18
Thermal Considerations
If a converter, mounted on a PCB, is located in free, quasi-
stationary air (convection cooling) at the indicated maxi-
mum ambient temperature
T
A max (see table:
Temperature
specifications
) and is operated at its nominal input voltage
and output power, the case temperature
T
C measured at
the
Measuring point of case temperature
T
C (see:
Mechani-
cal Data
) will approach the indicated value
T
C max after the
warm-up phase. However, the relationship between
T
A and
T
C depends heavily on the conditions of operation and inte-
gration into a system. The thermal conditions are influ-
enced by input voltage, output current, airflow, temperature
of surrounding components and the surfaces and proper-
ties of the printed circuit board.
T
A max is therefore only an
indicative value and under practical operating conditions,
the ambient temperature
T
A may be higher or lower than
this value.
Caution: The case temperature
T
C measured at the:
Measuring point of case temperature
T
C (see:
Mechani-
cal Data
) may under no circumstances exceed the
specified maximum value. The installer must ensure that
under all operating conditions
T
C remains within the lim-
its stated in the table:
Temperature specifications.
Short Circuit Behaviour
The current limit characteristic shuts down the converter
whenever a short circuit is applied to an output. It acts self-
protecting and automatically recovers after removal of the
overload condition (hiccup mode).
Overtemperature Protection
The converters individual power trains are protected from
possible overheating by means of an internal temperature
monitoring circuit. It shuts down the unit above the internal
temperature limit and attempts to automatically restart. This
feature prevents from excessive internal temperature build-
ing up which could occur under heavy overload conditions.
Connection in Series
The outputs of one or several single or double output power
trains may be connected in series without any precautions.
Connection in Parallel
The outputs of one or several double output power trains
(except 3.3 or 5.1 V types) with equal nominal output volt-
age can be connected in parallel. Approximate current
sharing between 2 or several power trains is ensured by
their load dependent output characteristic.
Fig. 8
U
o
versus I
o
(typ) of units with U
o
= 5.1 V.
(40 IMX 35-05D12-9).
Fig. 9
U
o1/2
versus I
o1/2
of double output power trains
(i.e. 2
×
12 V).
See:
Block diagram 1
7
8
9
10
11
12
13
Uo [V]
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 Io total [A]
0
05020
5.5
5.0
4.5
4.0
3.5
3.0 012345
I
o
[A]
U
o
[V]
05019
Output Overvoltage Protection
The outputs of the converter are protected against overvolt-
ages by a second control loop. In the event of an overvolt-
age on one of the outputs the unit will shut down and
attempt to restart in short intervals. The main purpose of
this feature is to protect against possible overvoltages
which could occur due to a failure in the feedback control
circuit. The overvoltage protection is not designed to with-
stand externally applied overvoltages.
Typical Performance Curves
General conditions:
– T
A = 25oC, unless
T
C is specified.
– Shut down pin left open circuit.
– Trim input not connected.
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
10/18
11.0
11.5
12.0
12.5
13.0
13.5
U
o4
[V]
0.06 0.20 0.30 0.40 0.50 0.60 0.70
I
o1
[A]
0.10
05164
I
o4
= 0.35 A
I
o4
= 0.035 A
Fig. 10
Cross load regulation U
o4
versus I
o1
(typ) for various I
o4
for
Vo1, Vo4 on power train 1. See: Block diagram dual out-
put types. (20 IMX 35 D12D12-9)
Fig. 11
Flexible load distribution on power train 1 of
40 IMX 35 D12D12-9 (4
¥
12 V) with load variation from
0...150% of P
o1 nom
on output 1 (Vo1). Output 2 (Vo4)
loaded with 50% of P
o4 nom
.
U
o1
,
U
o2
[V]
I
o1
I
o1 nom
05039
14
13
12
11
10 025
50 75 100 150 [%]
U
o2
U
o1
125
60
70
80
90
h [%]
50 75 100
P
o
P
o total
25
05152
[%]
U
i min
U
i nom
U
i max
60
70
80
90
h [%]
50 75 100
P
o
P
o total
25
05153
[%]
U
i min
U
i nom
U
i max
Fig. 12
Efficiency versus input voltage and load. Typical values
40 IMX 35 D12D12-9 Fig. 13
Efficiency versus input voltage and load. Typical values
20 IMX 35 D12D12-9
70
100
U
o [%]
t
[ms]
05041
8.5
60.5
60.5
overload short circuit condition
switch-off
Fig. 14
Overload switch off (hiccup mode), typical values.
Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
11/18
Auxiliary Functions
Shut Down Function
The outputs of the converters may be enabled or disabled
by means of a logic signal (TTL, CMOS, etc.) applied to the
shut down pin. If the shut down function is not required then
it should be left open-circuit.
Converter operating: 2.0...20 V
Converter shut down: –10...0.7 V
Programmable Input Undervoltage Lockout PUL
A special feature of these units is the accurate undervoltage
lockout protection which protects the units (and system)
from large currents caused by operation at low voltages.
This ensures easier start-up in distributed power systems.
Table 7: Turn on and turn off voltage
Type Trigger level Hysteresis Units
20 IMX 35 7...8 ≤0.5 V
40 IMX 35 14...15.5 ≤1
See:
Electrical input data
for a description of the turn on
turn off voltage levels of the various types.
The under voltage lockout levels may be programmed by
use of an external resistor to Trim up the preset levels as
indicated in the table below.
Table 8: Typical values for R
ext
and the respective lockout
voltage for input voltage.
20 IMX 35 40 IMX 35
R
ext [kΩ]
U
min [V]
R
ext [kΩ]
U
min [V]
36 10 27 22
18 12 10 26
12 14 0 30
∞≤8∞≤15.5
Adjustable Output Voltage
As a standard feature, the IMX 35 offer adjustable output
voltages in the range 80...105% of
U
o nom by use of a con-
trol input pin. The Trim control is offered either on primary or
secondary side of the converter depending on type.
For the dual output types refer to the block diagram 1.
The units IMX 35-03-05 and IMX 35-05-05 feature a first
power train with magnetic feedback and synchronous recti-
fier. The simplified circuit is shown in Fig. 15.
The Trim1 (pin 18) is secondary referenced and influences
only the first power train. Adjustment of the output voltage is
possible by means of an external resistor
R
ext between the
Trim1 pin and either Vo1+ or Vo1–. If the control input is
left open circuit, the output voltage is set to
U
o1 nom. Table 9
lists typical values required to program the output voltage to
approximately the values of
U
o1 indicated.
Vo1+
Vi+
Vi–Vo1–
06136
Trim1
R
ext1
R
ext2
4
2
17
18
15
Fig. 15
Output voltage control for the Trim1 input referenced to
the secondary side.
Table 9: U
o1
versus R
ext
for U
o1
= 80...105% U
o nom
; typical
values (U
i nom
, I
o1/2
= 0.5 I
o1/2 nom
)
U
o nom
R
ext1
R
ext2
[V]
U
o1 [V] [kΩ]
U
o1 [V] [kΩ]
3.3 2.5 1.1 3.3 ∞
2.46 2.1 3.47 11
2.97 8 3.673 5
5 3.33 0.23 5 ∞
3.57 0.45 5.36 10
4.08 1.3 5.61 5
4.59 3.5
The units INX 35-12-12 and IMX 35-15-15 exhibit a Trim
input connected to pin 5. This input influences both outputs
simultaneously. Both power trains have passive trans-
former feedback and the Trim input (pin 5) is referenced to
the primary side. Fig. 16 shows the circuit topology. Adjust-
ment of the output voltage is possible by means of either an
external resistor
R
ext in the range of 100...105% of
U
o nom or
an external voltage source in the range of 80...105% of
U
o nom.
Trim
Vo1+
Vo2–
+
U
ext
–
Vi+
Vi–
R
ext
Vo1–
Vo2+
06137
Control
circuit
U
ref
= 2.5 V
4
5
2
17
15
13
11
Fig. 16
Output voltage control for double output units by means of
the Trim input on the primary side.
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
12/18
Synchronisation (W)
This logic input can be used to synchronise the oscillator to
an external frequency source. This pin is edge triggered
with TTL thresholds, and requires a source frequency of
460...520 kHz (duty cycle 10...90%). The external source
frequency is internally divided by two to define the switching
frequency for the converter. If unused, this pin can be con-
nected to V1– (pin 2) or left open-circuit.
Reference (Ref)
This option provides a stable 5 V (±0.2 V) reference signal
on pin Ref. It is buffered through a 1.33 kΩ resistor. This
may be used also in conjunction with the Trim input pin 5
(primary side) as a limited external voltage source. We
recommend to connect a filter capacitor (0.1 µF) between
Ref and Vi–, if Vref is used.
a) Adjustment by means of an external resistor
R
ext:
Adjustment of the output voltage by means of an external
resistor
R
ext is possible within the range of 100...105% of
U
o nom.
R
ext should be connected between the Trim pin 5
and Vi–. Connection of
R
ext to Vi+ may damage the con-
verter. The following table indicates suitable resistor val-
ues for typical output voltages under nominal conditions
(
U
i nom,
I
o = 0.5
I
o nom).
b) Adjustment by means of an external voltage source
U
ext.
For external output voltage adjustment in the range
80...105% of
U
o nom a (0...20 V) source
U
ext is required,
connected to the Trim pin 5 and Vi–. The table below indi-
cates typical
U
o versus
U
ext values. Applying a control
voltage 15...20 V will set the converter into a hiccup
mode. Direct paralleling of the Trim pins of units of the
same type connected in parallel is feasible.
Table 11: U
o
versus U
ext
for U
o
= 80...105% U
o nom
;
typical values (U
i nom
, I
o
= 0.5 I
o nom
)
U
o [%
U
o nom]
U
ext [V]
≥105 0
102 1.8
100 2.5
95 4.25
85 8.25
80 10.2
Table 10: R
ext1
for U
o
> U
o nom
;
approximate values (U
i nom
, I
o
= 0.5 I
o nom
)
U
o [%
U
o nom]
R
ext [kΩ]
105...108 (107 typically) 0
105 3.3
104 6.2
103 10
102 18
101 39
100 ∞
The block diagram 2 shows the triple output units. They of-
fer a Trim1 input (pin 18) on the secondary side to adjust
U
o1. The other outputs remain unchanged. Pin 18 is not
connected. Refer to Fig. 15 for the schematic and Table 8 to
determine
R
ext.
The quadruple output units are shown in block diagram 3 All
types with equal output voltage have the Trim function con-
nected to pin 5 which influences all outputs simultaneously.
The schematics shown Fig. 16, the values of the adjust re-
sistor
R
ext in Table 10 and the external voltage source in
Table 11.
Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
13/18
Electromagnetic Immunity
Table 12: Immunity type tests
Phenomenon Standard 1 Class Coupling Value Waveform Source Test In Per- 3
Level mode 2 applied Imped. procedure oper. form.
Electrostatic IEC/EN 2 contact discharge 4000 Vp1/50 ns 330 Ω10 positive and yes B
discharge 61000-4-2 (R pin open) 10 negative
to case 3 air discharge 8000 Vpdischarges
(R pin open)
Electromagnetic IEC/EN 3 antenna 10 V/m AM 80% 26…1000 MHz yes A
field 61000-4-3 1 kHz
ENV 50204 PM, 50% duty 900 MHz
cycle, 200 Hz
resp. frequ.
Electrical fast IEC/EN 4 direct +i/–i 4000 Vpbursts of 5/50 ns 50 Ω1 min positive yes B
transient/burst 61000-4-4 5 kHz rep. rate 1 min negative
transients with transients per
15 ms burst coupling mode
duration and a
300 ms period
Surge IEC/EN 3 +i/–i 2000 Vp1.2/50 µs2 Ω5 pos. and 5 neg. yes B
61000-4-5 5 impulses per
coupling mode
Conducted IEC/EN 3 +i/–i 10 Vrms AM modulated 50 Ω0.15...80 MHz yes A
disturbancies 61000-4-6 (140 dBµV) 80%, 1 kHz 150 Ω
Transient ETR 283 +i/–i 150 Vp0.1/0.3 ms limited to 3 positive yes B
(19 Pfl 1) 4 <100 A
1Related and previous standards are referenced in:
Technical Information: Standards
.
2i = input, o = output.
3A = normal operation, no deviation from specification, B = temporary deviation from specs. possibe.
4For 40 IMX 35 types (additional external components required). Not applicable for 20 IMX 35 types.
5External components required.
which typically occur in many installations, but especially in
battery driven mobile applications.
Electromagnetic Compatibility (EMC)
A suppressor diode together with an input filter form an ef-
fective protection against high input transient voltages
Fig. 17
Typical disturbance voltage (quasi-peak) at the input ac-
cording to CISPR 11/EN 55011 and CISPR 22/EN 55022,
measured at U
i nom
and I
o nom
. Output leads 0.1 m, twisted.
(40 IMX 35-D12D12-9)
Electromagnetic Emission
07020
EN 55022 A
EN 55022 B
90
80
70
60
50
40
30
20
10
0
0
.01
0
.05
0.1
0.5
1
2
5
10
20
30
[dBµV]
MHz
0
.02
50
40
30
20
10
0
30
50
100
200
500
1000
[dBµV/m]
[MHz]
A
B
07108
Fig. 18
Typical radio frequency-interference voltage at U
i nom
,
I
o nom
, measured with an antenna (distance 10 m).
Output leads 1 m, twisted.
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
14/18
Table 16: Mechanical stress
Test Method Standard Test Conditions Status
Ca Damp heat IEC/DIN IEC 60068-2-3 Temperature: 40 ±2 °C Unit not
steady state MIL-STD-810D section 507.2 Relative humidity: 93 +2/-3 % operating
Duration: 56 days
Ea Shock IEC/EN/DIN EN 60068-2-27 Acceleration amplitude: 100
g
n = 981 m/s2Unit
(half-sinusoidal) MIL-STD-810D section 516.3 Bump duration: 6 ms operating
Number of bumps: 18 (3 each direction)
Eb Bump IEC/EN/DIN EN 60068-2-29 Acceleration amplitude: 40
g
n = 392 m/s2Unit
(half-sinusoidal) MIL-STD-810D section 516.3 Bump duration: 6 ms operating
Number of bumps: 6000 (1000 each direction)
Fc Vibration IEC/EN/DIN EN 60068-2-6 Acceleration amplitude: 0.35 mm (10...60 Hz) Unit
(sinusoidal) MIL-STD-810D section 514.3 5
g
n = 49 m/s2 (60...2000 Hz) operating
Frequency (1 Oct/min): 10...2000 Hz
Test duration: 7.5 h (2.5 h each axis)
Fda Random vibration IEC 60068-2-35 Acceleration spectral density: 0.05
g
n2/Hz Unit
wide band Frequency band: 20...500 Hz operating
reproducibility Acceleration magnitude: 4.9
g
n rms
high Test duration: 3 h (1 h each axis)
Kb Salt mist, cyclic IEC/EN/DIN IEC 60068-2-52 Concentration: 5% (30°C) Unit not
(sodium chloride Duration: 2 h per cycle operating
NaCl solution) Storage: 40°C, 93% rel. humidity
Storage duration: 22 h per cycle
Number of cycles: 3
CISPR 22/EN 55022, Level B Radiated
Electromagnetic emission requirements according to
EN 55022, class B (radiated emmission) can be achieved
by adding an external common mode choke and (for
20 IMX 35 types) an additional capacitor, see:
Input Data
.
The filter components should be placed as close as possi-
ble to the input of the converter.
Fig. 20
Choke dimensions
Vi+
Vi–
L
V+
V–
Module
07114
Fig. 19
Example for external circuitry to comply with CISPR22/EN
55022, level B, radiated
15 8.5
15
07110
Table 13: Input filter components for EN 55022, level B,
radiated.
Type Current compensated choke
20 IMX 35
40 IMX 35
Table 14: Temperature specifications, valid for air pressure of 800...1200 hPa (800...1200 mbar)
Temperature -7 -9 Option -8 3
Characteristics Conditions min max min max min max Unit
T
AAmbient temperature 1 Operational 2 –25 71 –40 71 –40 85 °C
T
CCase temperature –25 95 –40 95 –40 105
T
SStorage temperature 1 Non operational –40 100 –55 100 –55 105
1MIL-STD-810D section 501.2 and 502.2
2See:
Thermal Considerations
3Start up at –55°C
Table 15: MTBF and device hours
MTBF Ground Benign Ground Fixed Ground Mobile
MTBF acc. to MIL-HDBK-217F
T
C = 40°C
T
C = 40°C
T
C = 70°C
T
C = 50°C
40 IMX 35 h h h h
Immunity to Environmental Conditions
Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
15/18
Mechanical Data
Dimensions in mm. Tolerances ±0.3 mm unless otherwise indicated.
Fig. 21
Case IMX 35 (Standard)
Weight: 67 g
European
Projection
63.5
76.2
63.5
0.8 x 0.8
5.08
510.5
09121
69.6
56.9
thread M3
5.08
47.8
63.5
72.8
6.4 8.9
0.8 x 0.8
09123
Fig. 22
Case IMX 35 open frame (option Z)
Weight: 43 g
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
16/18
Safety and Installation Instructions
Installation Instructions
Installation of the DC-DC converters must strictly follow the
national safety regulations in compliance with the enclo-
sure, mounting, creepage, clearance, casualty, markings
and segregation requirements of the end-use application.
Connection to the system shall be made via a printed circuit
board with hole diameters of 1.5 mm for the pins.
The units should be connected to a secondary circuit.
Check for hazardous voltages before altering any connec-
tions.
Do not open the module.
Ensure that a unit failure (e.g. by an internal short-circuit)
does not result in a hazardous condition. See also:
Safety
of operator accessible output circuit.
Input Fuse
To prevent excessive current flowing through the input sup-
ply line in case of a short-circuit across the converter input
an external fuse should be installed in a non earthed input
supply line. We recommend a fast acting fuse F8.0A for
20 IMX 35 types, F4.8 A for 40 IMX 35 types.
Standards and approvals
All DC-DC converters are pending to be UL recognized ac-
cording to UL 1950, UL recognized for Canada to CAN/
CSA C22.2 No. 950-95 and LGA approved to IEC/EN
60950 standards.
The units have been evaluated for:
•Building in
•Supplementary insulation input to output, based on their
maximum input voltage (IMX 35 types)
•The use in a pollution degree 2 environment
•Connecting the input to a secondary circuit which is sub-
ject to a maximum transient rating of 1500 V
After approvals the DC-DC converters are subject to manu-
facturing surveillance in accordance with the above men-
tioned UL, CSA, EN and with ISO 9001 standards.
Isolation
The electric strength test is performed as factory test in ac-
cordance with IEC/EN 60950 and UL 1950 and should not
be repeated in the field. Melcher will not honour any guar-
antee claims resulting from electric strength field tests.
Table 17: Electric strength test voltages
Characteristic Input to output Output to Unit
IMX 35 output
Electric strength 1.2 0.1 kVrms
test voltage 1 s 1.5 0.5 kV DC
Insulation resistance >100 - MΩ
at 500 V DC
Partial discharge Consult factory - kV
extinction voltage
Table 18: Pin allocation
Pin No. Double Triple Quadruple
output output output
1 PUL PUL PUL
2Vi–Vi–Vi–
3 n.c. n.c. n.c.
4 Vi+ Vi+ Vi+
5 Trim or n.c. n.c. Trim
6W W W
7 Ref Ref Ref
8 SD or i SD or i SD or i
11 Vo2–Vo3–Vo3–
12 n.c. Vo3+ Vo3+
13 Vo2+ Vo2+ Vo2+
14 n.c. Vo2–Vo2–
15 Vo1–Vo1–Vo1–
16 n.c. Trim1 Vo1+
17 Vo1+ Vo1+ Vo4+
18 Trim1 or n.c. –Vo4–
19 n.c. n.c. n.c.
Fig. 23
Pin allocation
Protection Degree
The protection degree of the DC-DC converters is IP 30
(not for option Z).
Cleaning Agents
In order to avoid possible damage, any penetration of
cleaning fluids should be prevented, since the power sup-
plies are not hermetically sealed.
09122
1
2
3
4
5
6
7
8
11
12
13
14
15
16
17
18
19
Bottom
view
Rugged Environment DC-DC Converters <40 Watt IMX 35 Series
Edition 1/10.99
17/18
Table 19: Insulation concept leading to an SELV output circuit
Conditions Front end DC-DC converter Result
Supply Minimum required grade Maximum Minimum required Type Measures to achieve the Safety status of
voltage of isolation, to be provided DC output safety status of the specified safety status of the DC-DC
by the AC-DC front end, voltage front end output the output circuit converter output
including mains supplied from the circuit circuit
battery charger front end 1
Mains Basic ≤60 V Earthed SELV circuit 2 IMX 35 Operational insulation SELV circuit
≤250 V AC (provided by the DC-DC
converter)
≤75 V Hazardous voltage IMX 35 Input fuse 3 output sup- Earthed SELV
secondary circuit pressor diodes 4, and circuit
earthed output circuit 2
Double or reinforced ≤60 V SELV circuit IMX 35 Operational insulation
(provided by the DC-DC
converter)
≤75 V Double or reinforced IMX 35 Supplementary insulation
insulated unearthed based on the maximum
hazardous voltage rated output voltage from
secondary circuit 5 the front end (provided by
the DC-DC converter)
Safety of operator accessible output circuit
If the output circuit of a DC-DC converter is operator acces-
sible, it shall be an SELV circuit according to the IEC/EN
60950 related safety standards
The following table shows some possible installation con-
figurations, compliance with which causes the output circuit
of the DC-DC converter to be an SELV circuit according to
IEC/EN 60950 up to a configured output voltage (sum of
nominal voltages if in series or +/– configuration) of 42 V.
However, it is the sole responsibility of the installer to en-
sure the compliance with the relevant and applicable safety
regulations. More information is given in:
Technical Infor-
mation:
Safety
.
1The front end output voltage should match the specified input voltage range of the DC-DC converter.
2The earth connection has to be provided by the installer according to the relevant safety standard, e.g. IEC/EN 60950.
3The installer shall provide an approved fuse (type with the lowest rating suitable for the application) in a non-earthed input conductor
directly at the input of the DC-DC converter (see fig.:
Schematic safety concept
). For UL’s purpose, the fuse needs to be UL-listed.
See also:
Input Fuse
.
4Each suppressor diode should be dimensioned in such a way, that in the case of an insulation fault the diode is able to limit the output
voltage to SELV (<60 V) until the input fuse blows (see fig.:
Schematic safety concept
).
5Has to be insulated from earth by at least basic insulation according to the relevant safety standard, based on the maximum output
voltage from the front end.
AC-DC
front
end
DC-DC
con-
verter
Mains
Fuse
Battery
Earth
connection
Suppressor
diode SELV
Earth
connection
+
–
~
~
10004
Fig. 24
Schematic safety concept. Use fuse, suppressor diode
and earth connection as per table:
Safety concept leading
to an SELV output circuit
.
IMX 35 Series DC-DC Converters <40 Watt Rugged Environment
Edition 1/10.99
18/18
Description of Option
Option -8
Extended Temperature Range
Extension of the temperature range from standard
–40...71°C to –40...85°C. In the upper temperature range
the output power derating below should be observed. The
modules will provide the specified ouptut power with free air
convection cooling.
Option i
Inhibit
The output of the converter may be enabled or disabled by
means of a logic signal (TTL, CMOS, etc.) applied to the
inhibit pin. No output voltage overshoot will occur when the
unit is turned on. If the inhibit function is not required the
inhibit (pin 8) should be connected to Vi– to enable the out-
put (active low logic, fail safe).
Converter operating: –10 V...0.8 V
Converter inhibited
or inhibit pin left open circuit: 2.4 V...
U
i max
Fig. 26
If the inhibit is not used the inhibit pin should be con-
nected to Vi–
Vi+
Vi–
i
06138
4
8
2
1.2
1.0
0.8
0.6
0.4
020
–20 60
0.2
40 80
P
o
/
P
o max
T
A
[°C]
–40 0
11047
Fig. 25
Maximum allowed output power versus ambient tempera-
ture.
Option Z
Open Frame Version
