AD53500: Thermal questions

Document created by analog-archivist Employee on Feb 23, 2016
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Thermal questions
We use in one of our product the AD53500 driver, and we notice that
these components produce a lot of heat in static mode that is to say
with a fixed voltage on the input.
We'd like to know if it corresponds to a normal operating or if it is
necessary to mount heat sink on these components.
More, it is possible to have thermal information about this chip.


AD53500 is capable of producing a lot of heat, even in static conditions. The
device can produce up to 1.54W quiescent current + >2W (=180mA x 12V?) if the
output is shorted to -2V.

This is a lot of power! The junction-to-ambient thermal impedance is 49.1
degC/W (with some air moving over the part). Even with the quiescent power
dissipation of 1.54W the internal junction is about 75 Degrees above ambient
(dT = thJA x P = 49.1 x 1.54 = 75.6deg C)
So at room temperature of 25 deg, the internal junction temperature is at
100deg C
At 50degC (typical of the inside of electronic equipment) the junction
temperature is 125 deg C

This is before you draw any current from the outputs. As you can see, the parts
run very hot. The package is a thermally enhanced SOIC to allow a heatsink to
be mounted. You might also consider using forced air cooling (a cooling fan).

The thermal information on the part is given on table II (page 4) of the
AD53500 datasheet.