Power calculation for ADuM3070

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Feb 23, 2016
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Attached you can see a block diagram of our power design. Is the ADuM3070 /
4070 able to deliever enough power for this design in the 5V -> 5V
configuration? Total power on the galvanic isolated loads should be
180mW+66mW+900mW = 1.146W. But it is plenty of power dissipation on the LDO’s.
What do you think?

 

Assuming 80% efficiency for the dc to dc for the +/-20V means about 250mA
current from the ADuM3070 5V, plus the 80mA, 25mA and 20mA from the other LDOs
gives a total of 375mA at 5V output.  This meets the 400mA specified for the
ADuM3070. You just need to use the specified or better components in the
ADuM3070 application circuit, especially the schottky diodes.

You should check on the efficiency of the dc to dc that provides the +/-20V
since if this were low, say 70%, would draw a total 410mA, 10mA over specified.

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