BCD20009-G Rev AA
Page 7 of 16
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IMX35 Series Data Sheet
35-Watt Quad-Output DC-DC Converters
Fig. 5
Maximum allowed output power versus ambient
temperature.
Overtemperature Protection
The converter is protected against possible overheating by
means of an internal temperature monitoring circuit. It shuts
down the converter above the internal temperature limit and
attempts to automatically restart. This feature prevents
excessive internal temperature building up which could occur
under heavy overload conditions.
Thermal Considerations
If a converter, mounted on a PCB, is located in free, quasi-
stationary air (convection cooling) at the indicated maximum
ambient
temperature
TA max
(see
table
Temperature
specifications) and is operated at its nominal input voltage and
output power, the case temperature TC measured at the
measuring point of case temperature (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 are influenced by input
voltage, output current, airflow, temperature of surrounding
components and the surfaces and 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 than this value.
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 value. The installer
must ensure that under all operating conditions TC remains within
the limits stated in the table Temperature specifications.
The converters provide the specified output power with free air
convection cooling. In the upper temperature range the output
power derating below should be observed.
1.0
0.8
0.6
0.4
0
0.2
20
40
60
80
100
°C
Po/Po max
11047-X35
TA
0.5 m/s = 200 LFM
natural cooling
Short Circuit Behavior
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).
Fig. 6
Overload switch off (hiccup mode), typical values.
Connection in Series
The outputs of one or several double output power trains may
be connected in series without any precautions.
Connection in Parallel
Several outputs of the same converter with equal output
voltage (e.g., 5 V / 5 V) can be connected in parallel and will
share their output currents almost equally.
If outputs from the same converter are being paralleled
together, it is recommended that outputs from the same power
trains are connected together first.
Note: A separate application note is available for uses when all
outputs are paralleled together.
Parallel operation of several converters with the same output
voltage may cause start-up problems at initial start-up. This is only
advisable in applications where one converter is able to deliver the
full load current as is required in true redundant systems. It is
recommended not to parallel more than three units at full load.
70
100
Vo [%]
t
05041b
0.3 s
overload short-circuit condition
switch-off
0