Current consumption on AVdd and Vdrive individually - for power supply dimensioning

Document created by analog-archivist Employee on Feb 23, 2016
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In the data sheet is just the sum current for AVcc and Vdrive specified.
What is their individual value for the normal operation mode (maximum value)?
I need this values to dimension the power supplies.

Our configuration is the following:
We use all eight channels (AD7606). We intend to use oversampling. The internal
reference is used and the serial interface is connected.

 

For this configuration Vdrive is expected to draw less than 100uA. A typical
value is 40uA, but this depends on the capacitive load on DoutA and DoutB pins,
as well as specific Vdrive voltage level.

Note that the 100uA number is based on an oversampling case, and therefore the
contribution from the Vdrive during the read operation is averaged over a very
large period compared to the read duration, and it is also based on a small
capacitive load (10pF) on the Dout.
So, for example at 2.5V Vdrive, 10pF load, and 32us time between conversions,
the Vdrive current would be approximately 100uA. It will scale approximately
proportionately with capacitive load and Vdrive voltage, and inversely with
time between conversions.
Figure 32 in the RevC datasheet shows typical total AVcc current consumption vs
oversampling rate. So when oversampling mode is turned on, the AVcc current
consumption is typically close to 20mA.

For your information, the total AVCC current is shared approximately equally
between the four AVCC pins in that mode also, but up to 6mA should be allowed
on any individual AVCC pin .

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