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PulSAR AD7980 driven by AD8615 and AD8426 and GND

Question asked by Damien on Jan 24, 2013
Latest reply on Jan 28, 2013 by Damien

Hello,

 

I'm quite new with analog and I try to catch-up on the design with these devices.

 

My first question is will the AD8615 will be able to drive AD7980 at 1MSPS ?

 

Second, my PCB has separated analog and digital ground, but the AD7980 has a single GND. To get the best performances, the GND should be tied to the digital or analog ground ? I would say digital as IN- is at the analog ground.

 

Second question, my AD7980 is supplied in 2.5V by a microchip 2.5V reference voltage able to supply 2mA. I haven't been able to find the current consumption on the datasheet but calculated from the power consumption it should be around 10mA, but seems most of the current is sunk from the Ref pin. The VIO is supplied at 3V3.

 

To summarize:

VDD : 2.5V 2mA

Ref:    3V 10mA

VIO:   3V3 100mA

Main supply is 3.3V

 

Will that be sufficient ?

 

I would also like to keep compatibility with AD7988-5 for low cost.

 

Also I'm limited in term of size.

 

Thanks

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