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ADS7805: ADS7805 Tantalum cap replacement at pins 3 and 4.

Part Number: ADS7805

A customer of mine is using the ADS7805.

The TI datasheet advices to use a 2.2uF Tantalum capacitor at pin 3 and 4 (REF and CAP).

The customer wants to use a different capacitor (have been using ALcaps, that become obsolete now.)

Would it be OK to use a 2.2uF/25V ceramic capacitor like X7R or better as alternative?

If not what capacitor type do you propose?

  • Hi Jan,

    Yes, that is ok to do.  Using an X7R or better would be good so that the capacitance stays stable over temperature. 

    Mike

  • Hi Jan,

    Pin 4 is a reference buffer output CAP pin. On some parts the output of the buffer can become unstable when the tantalum is replaced with a ceramic, because the ESR of the tantalum helps with the reference buffer stability. I don't know if this will happen with the ADS7805 if the tantalum is replaces with a ceramic. You can add a small ( 1ohm) resistor in series with the ceramic to make sure that the buffer stays stable.

    Mike