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ADS8509: Input impedance is different.

Motoyasu Hattori
Genius 12185 points

Part Number: ADS8509
Other Parts Discussed in Thread: ADS7809

Hi,
My customer claims input impedance on Table2 is different from Equivalent circuit on ADS8509.
According to the datasheet, 10kohm is connected with REF Buffer as follows:

However, my customer says 10kohm should be connected with GND, also ADI AD977 is also connected with GND.  That is why he is asking.  Please advise us.

Thanks and best regards,
M.HATTORI.

  • 0
    TI__Guru**** 182601 points

    Hi Hattori-san,

    Yes, the block diagram on the first page should show the series resistor to ground.  The ADS8509 is not a direct replacement for the competitor part you mentioned.  Please look at the ADS7809 which has the same input impedance (and block diagram error).