AD8228 output swing

Dear Sir:

               I used AD8228 to measure shunt current and used AD8253 to measure voltage as below circuit , We have a issue that when we tie +IN and -IN to GND  then Vout will measure 5.7V swing. When we remove AD8253 then AD8228 Vout=2.5V(Normal). What's wrong for this circuit ? Do you have any suggestion? Below is detailed condition for your reference.

Best Regards

Jason

AD8228:

              +VS=7.5V

                REF=2.5V

               -VS=-5V

AD8253:

               +VS=7.5V

                REF=2.5V

               -VS=-GND

               A0/A1=GND

               WR=-5V

               

    

  • 0
    •  Analog Employees 
    on Dec 21, 2016 8:24 PM over 4 years ago

    Hi Jason,

    It seems that  there are discrepancies between the drawing and the condition that you mentioned.

    Can you confirm the setup for the AD8253?

    Supply voltage for the AD8253 should be at least 10V and therefore -Vs should be connected to -5V as shown on your drawing.

    What amplifier gives the incorrect  voltage output? AD8228 or AD8253?

    What is Vs and L? can you show the complete schematic of the input side of the inamp especially when you short the input to ground.

    Best regards,

    Emman

  • Dear Emman:

                            Sorry for my careless, Correct setup of AD8253 as below:

    +VS=7.5V

    -VS=-5V

    REF=GND

    A0/A1=GND

    WR=-5V

                       For schematic of the input side , We tried to tie +IN/ -IN to GND to watch offset of AD8228. but It measure 5.7V swing from AD8228 Vout.

    Best Regards

    Jason