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Replacing LMV84x by AD8646/8648 ?

Question asked by usaghi on May 8, 2015
Latest reply on May 12, 2015 by JGunao

Hi,

 

We are now studying to replace LMV84x on existing system by AD8646 or AD8648, then having questions as follows.

 

1) Absolute Maximum Ratings of input voltage at AD8646/8648 is defined as "GND to Vsy".

  I could not find any clear definition in the datasheet what is Vsy, but assuming it has to be Supply Voltage, from analogy of Isy defined as Supply Current Per Amplifier.

  Is this true ? Correct me if wrong.

 

2) When using AD8646/8648 at 5V single supply, however input voltage can be the rage from  -(minus)0.3 to 0V.

  It seems out of range defined on Absolute Maximum Ratings in the datasheet, so is it not available to use, even if it is only an instant of eye blink ?

  Please make sure if it is correct.

 

3) LMV84x is RRin and RRout, 5V single supply but it is still available to  -(minus)0.3V input voltage.

  I looked for the same ADI parts and found AD8607/AD8609, but their GBP is around 300KHz, and we need a few MHz bandwdth.

  Could you provide other ADI parts which fullfill above conditions (R-R in, R-R out, single supply 5V,  -0.3~0V input voltage, GBP=a few MHz) ?

  Hopefully Vos (Offset Voltage) is a few handreds uV range and Ib (Bias Current) is around 1pA, not to be far outweighed by LMV84x.

 

Best Regards,

Usaghi

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