ADuM6132 overheating

Document created by analog-archivist Employee on Feb 23, 2016
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We are using 2 x ADUM6132 to drive a complete bridge , and we observe a heating
of both ADUM6132 (even without switching). In the data sheet, only the maximum
Quiescent current (280mA) is specified, and not the typical one...
It is not easy to measure the quiescent current on my board, but it seems to be
around 200mA per IC, which seems a lot!!  If it is correct, it means 1W per IC
and with a thermal resistor of 45°/W, a heating of +45°C!!


Overheating can be an issue with applications of the ADuM6132, especially at no
load conditions. The ADuM6132 can consume over 200mA at no load. The output
voltage is not regulated and at no load the output needs to be protected from
exceeding the 18V maximum rating, so there is an internal circuit which will
clamp the output voltage which will cause an internal load that need to be
dissipated in the ADuM6132. At no load the internal power can be 1W and can
cause a temperature rise of 45C. The temperature could rise even more if
provisions are not taken in the layout to help remove heat within the ADuM6132.
Page 12 of the datasheet states that enlarged pads should be added with
multiple vias from the ground pins to the ground planes to help remove heat
from the ADuM6132.