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BCD.00002 Rev AA, 3-Feb-2010
Page 5 of 15
www.power-one.com
IMX70, IMY70 Series Data Sheet
70 Watt DC-DC Converters
Reverse Polarity Protection and Fuse
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
Fuse type
24IMX70
40IMX70
110IMY70
Littlefuse 808, 2.5 A, 450 VDC, fast acting 1
1
UL-listed (E67006)
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.
Fig. 3
Inrush current at Vi nom, Po nom versus time (110IMY70-24-24-
8). Source impedance according to ETS 300132-2: L = 10
H, R = 1.5
Ω.
Fig. 4
Converter start-up and rise time
Fig. 5
Example for external circuitry to comply with IEC/EN 61000-
4-5; see table 10
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 to comply with
IEC/EN 61000-4-5; see table 10
Model
Inductor (L)
Capacitor (C)
24IMX70
40IMX70
110IMY70
--
150 F / 200 V
Input Transients Protection
When Vi is greater then 154 V, the converter is temporarily
disabled. Furthermore, a built-in suppressor diode provides
effective protection against higher input transients, which may
be generated for example by short-circuits across the input
lines.
Table 4: Built-in transient voltage suppressor
Model
Breakdown
Peak power
Peak pulse
voltage
at 1 ms
current
VBr nom [V]
Pp [W]
I pp [A]
24IMX70
40IMX70
110IMY70
176
600
2.5
Vo nom
Vo
tstartup
trise
t
04008b
t
JM028
0
20
40
60 μs
40
30
20
10
A
Vi+
Vi–
C
L
+
JM029