AD766x Current Consumption Calculation

Document created by analog-archivist Employee on Feb 23, 2016
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Do you have any information on current consumption calculations for AD766x
parts?

 

There is only a negligible difference in the current consumption on these parts
for differing input frequencies. In order to calculate the current consumption,
you first need to know what configuration you are going to use, that is what
modes you are going to use and at what decimation rate. You can then add up the
power requirements for each item from the datasheet.

For example for the AD7760, when using the whole lot i.e. Modulator + General +
Diff Amp + Ref Buffer then the currents AIDD1-4 (provided in the datasheet
power requirement specs on page 4) must be multiplied by their relevant voltage
supplies and then the digital DIDD*DVDD must also be added to give the full
power consumption for the mode.

This would be the max power for the part, when it's using all the features and
operating at the highest throughput rate 2.5MSPs. Any deviation from this (i.e.
not using the ref buffer or diff amp) will then reduce the power used.

There is also a power saving issue in the choice of decimation rate. The
digital current is all that's affected from decimation rate to decimation rate.
For the AD7760 over the full change from max throughput rate 2.5Mhz (dec x 8)
to 78Khz (dec x256) there is a circa 50% reduction in DIDD for the part. The
reduction in this current would not be as drastic for the AD7762/3 as the range
of decimation rates is smaller, but there would be some reduction. Over the
range of decimation rates the modulator and general currents will remain as is.
So once you know the mode and the decimation rate that you are going to use,
you can easily calculate the power requirements using the specs provided in the
AD776X datasheets.

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