NOV 18, 2004 revised to OCT 12, 2006
Page 7 of 12
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IMX4 DC-DC Series Data Sheet
4-Watt DC-DC Converters
Thermal Considerations
If a converter, mounted on a PCB, is located in free, quasi-
stationary air (convection cooling) at the maximum ambient
temperature TA max (see table: Temperature specifications)
and is operated at nominal input voltage and output power, the
case temperature TC measured at the measuring point of case
temperature TC (see: Mechanical Data) will approach the
indicated value TC max after the warm-up phase. However, the
relationship between TA and TC depends heavily on the
conditions of operation and integration into a system. The
thermal conditions depend on input voltage, output current,
airflow, temperature of surrounding components and surfaces
and the properties of the printed circuit board. TA max is
therefore only an indicative value, and under practical
operating conditions, the ambient temperature TA may be
higher or lower.
Caution:
The case temperature TC measured at the measuring
point of case temperature TC (see: Mechanical Data) may under no
circumstances exceed the specified maximum. The installer must
ensure that under all operating conditions TC remains within the
limits stated in the table: Temperature Specifications.
Short Circuit Behavior
The current limitation shuts down the converter, when a short
circuit is applied to the output. It acts self-protecting, and
automatically recovers after removal of the overload condition.
Output Overvoltage Protection
The outputs are protected against overvoltages by Zener
diodes. In the event of an overvoltage, the converter will shut-
down and attempt to restart automatically. 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
converters are not designed to withstand external overvoltages
applied to the outputs.
Connection in Series
The outputs of single or dual-output models can be connected
in series without any precautions, taking into consideration that
the output voltage should remain below 60 V for SELV operation.
Connection in Parallel
Several converters with equal output voltage can be connected
in parallel and will share their output current quite equally.
Fig. 9
Overload switch-off (hiccup mode).
70
100
Vo [%]
t [ms]
05041a
0.3 s
overload short circuit condition
switch-off
0
However, this may cause start-up problems and is only
recommended in applications, where one converter is able to
deliver the full load current, e.g., in true redundant systems.
Typical Performance Curves
Fig. 10
Vo versus Io (typ) of single-output models (20/40IMX4-05)
Fig. 11
Vo versus Io (typ.) of dual-output models (±15 V), with a 30 V
load connected to Vo+ and Vo –.
Fig. 12
Cross load regulation of dual-output models. Vo1 versus Io1
(typ) for various Io2 (40IMX4-1515).
5.25
5.0
4.75
4.5
4.25
4.0
0
0.1
0.2 0.3 0.4
0.5
0.6 0.7
0.8
0.9 1.0 Io [A]
Vo [V]
05056a
28.5
29
29.5
30
30.5
31
31.5
Vo1 + Vo2 [V]
20
40
60
80
100
120
140
Io [mA]
0
05057a
14
14.5
15
15.5
16
16.5
Vo1 [V]
20
40
60
80
100
120
140
Io1 [mA]
0
Io2 = 140 mA
Io2 = 14 mA
05058a