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AMC1200: can it operate with 2.5V common mode on input (and output)? Alternatives?

Robert Walker
Prodigy 10 points
Other Parts Discussed in Thread: AMC1200, ISO122, ISO124, ISO121, AMC1100

 
My application calls for an isolated signal measurement, where the sensing circuit on one side of barrier and the feed to rest of equipment - that is, primary and secondary side of isolation - both run on single-ended +5V supplies.
 
The analog front end is an INA333-series instrumentation amplifier with a single-ended output. That, through some filters, is fed into the isolating amplifier. The analog signal is centered about the midpoint of supply (I intend to set the reference somewhere at 2-2.5V), on both sides of the isolating amplifier.
 
 
I find that most isolating amplifiers that operate on single 5V supplies cannot accept inputs that are not close to ground; that is, cannot operate with common mode of 2.5V.
The one exception I see is the AMC1200.
My reading of the data sheet indicates that this part should operate with common mode of 2.5V.
 
Is that correct?
If not, can you recommend another device?
 
 
To re-iterate: my application calls for isolating amplifier operating at single +5V on both sides.
The analog signal is single-ended, centered around a 2.5V reference.
I intend to connect the negative input of the isolator to the 2.5V reference and the positive to the analog signal.
 
Similarly, on output side, I may also connect the negative output to a similar reference (as the output continues single-ended).
 
Is AMC1200 appropriate?
Any alternatives?
 
Thanks in advance.
 
Robert Walker
RD Walker Engineering
West Milford, NJ, USA

  • 0
    TI__Mastermind 46290 points

    Robert,

    The AMC1200 can accommodate the analog supply and analog input configurations that you have described, so long as the single ended analog signal you are describing is within 250mV peak to peak as the AMC1200 has a relatively narrow range of input voltages. 

    Other than the AMC1200 TI offers the AMC1100, ISO121, ISO122, and ISO124 in the way of isolation amplifiers. The AMC1200 and AMC1100 are the only fully differential choices.