75 Watt, High Density, Eighth Brick DC/DC Converter

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Over Temperature Protection

The ASD75EB series modules are protected from thermal overload by an internal over temperature protection

IC. When the PCB temperature sense point reaches 125°C, the converter will shut down immediately. The

converter will attempt to restart when the temperature has dropped at least 10°C below the Over

Temperature threshold.

Thermal Considerations

The ASD75EB series are designed to operate in a wide range of thermal environments. However, enough

cooling should be provided to ensure reliable performance. Heat is removed from the converter in 3 ways:

conduction, convection and radiation.

Improved cooling by convection can be done by increasing the airflow through the module. The available

load current for a given ambient air temperature is in the de-rating curves section. The test is done using

the test fixture shown in figure 5.

Figure 5: Thermal Test Fixture

Pin3

Pin1

Pin4

Pin8

Proper cooling can be verified by monitoring the temperature of the critical components of the power

stage. Each of the selected critical components was monitored by using thermocouple. The generation of

the thermal de-rating curves involves extensive thermal testing at different combinations of input voltage,

ambient air temperature, load current and airflow with the given test fixture.

However, the final temperature of the module in the final system will depend again on several factors,

including host PCB size, number of layers, and copper weight, airflow direction and turbulence, operating

ambient temperatures, etc… It is highly recommended to verify the thermal performance of the converter

when included in the end system.

ASD75

Figure 5: Thermal Text Fixture