®

IMX35 Series Data Sheet

35 Watt Quad-Output DC-DC Converters

BCD20009-G Rev AC, 06-May-2013

Page 7 of 15

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.

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).

Thermal Considerations

If a converter, mounted on a PCB, is located in free, quasi-

stationary air (convection cooling) at the indicated maximum

cations) and is operated at its nominal input voltage and output

at the measuring point of case temperature (see Mechanical

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

under practical operating conditions, the ambient temperature

measuring point of case temperature (see Mechanical Data) may

under no circumstances exceed the specified maximum value.

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.

Series and Parallel Connection

The outputs of one or several double-output power trains may

be connected in series respecting the current limitation.

Both outputs of the same power train can always be

connected in parallel in will behave like a single output.

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 of the same converter are being parallel and series-

connected, it is recommended that outputs from the same

power trains are parallel-connected first. This applies for

instance, if 24 V shall be generated by a converter with four

12 V outputs; see fig. 7.

Fig. 6

Overload switch off (hiccup mode), typical values.

Note: Parallel operation of several converters may cause start-

up problems. This becomes noticable in applications, where one

converter is not able to deliver allone the full resistive and

capacitive load current, as it is required in true redundant systems.

70

100

V

t

05041b

0.3 s

overload short-circuit condition

switch-off

0

1.0

0.8

0.6

0.4

0

0.2

20

40

60

80

100

°C

P

11047-X35a

T

A

0.5 m/s = 100 LFM

natural cooling

PWM

4

8

1

Vi+

SD

PUL

5

Trim

6

W

7

Ref

2

Vi–

16

15

17

18

13

14

12

11

Vo4–

Vo1+

Vo1–

Vo4+

Vo2+

Vo2–

Vo3+

Vo3–

JM138

3

n.c.

19

n.c.

–24V

+24V

IMX35D12D12-9

Fig. 7

Generating 24 V with an IMX35D12D12-9