®
IMX35 Series Data Sheet
35 Watt Quad-Output DC-DC Converters
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 in order to further reduce this
current.
A
4
3
2
1
0
20
40
60
80
t
100 µs
Input Transient Voltage Protection
A built-in suppressor diode provides effective protection
against input transients, which may be generated for example
by short-circuits across the input lines, where the network
inductance may cause high energy pulses.
Table 4: Built-in transient voltage suppressor
04022b
Model
Breakdown
voltage
V
Br nom
[V]
39
100
151
176
Peak power
at 1 ms
P
p
[Ω]
Ω
1500
1500
600
600
Peak pulse
current
I
pp
[A]
22
9.7
2.9
2.5
20IMX35
40IMX35
70IMX35
110IMX35
Fig. 2
Typical inrush current at V
i nom
, P
o nom
versus time (40IMX35).
Source impedance according to ETS 300132-2 at V
i nom
.
For very high energy transients as for example to achieve
IEC/EN 61000-4-5 compliance (as per table
Electromagnetic
Immunity)
an external inductor and capacitor are required. The
components should have similar characteristics as listed in
table below.
Table 5: Components for external circuitry for IEC/EN
61000-4-5, level 2
Model
t
startup
t
V
o
V
o nom
t
rise
04008b
Inductor (L)
22 µH /5 A
68 µH / 2.7 A
100 µH / 1 A
150 µH /0.8 A
Capacitor (C)
470 µF / 40 V
2 x 100 µF /100 V
2 x 82 µF /200 V
2 x 82 µF / 200 V
Diode (D)
1.5 k E47A
-
-
-
20IMX35
40IMX35
70IMX35
110IMX35
Fig. 3
Converter start-up and rise time (see table 2)
Reverse Polarity Protection
The built-in suppressor diode also provides for reverse
polarity protection at the input by conducting current in the
reverse direction. An external fuse is required to limit this
current.
Table 3: Recommended external fuses in the non-earthed
input line
Converter model
20IMX35
40IMX35
70IMX35
110IMX35
Fuse type
F8.0 A
F4.0A
F2.0A
F1.5A
L
Vi+
C
+
D
Vi–
04036a
Fig. 4
Example for external circuitry to comply with IEC/EN 61000-
4-5; the diode D is only necessary for 20IMX35 models.
BCD20009-G Rev AC, 06-May-2013
Page 5 of 15
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