Hi all
Would you mind if we ask INA240?
Could you refer to the attachment file?
20180402_INA240.pdf
There is the description "INA240 Maximum capacitive load 1nF(Typ.)."
In case of 1nF(Typ), does it have any trouble for stability?
According to 0ohms, if there is the trouble, could you let us know?
Kind regards,
Hirotaka Matsumoto
Hello Hirotaka,
Thank you for considering to use TI in your design. We do not recommend using a larger capacitor than 1nF if you are shorting the the INA240 output directly to the ADS7253 input as there could be stability issues. I presume that you read the ADS7253 anti-aliasing subsection of the application section as you have a filter capacitor that satisfies their recommendation for reducing sampling charge injection. The anti-aliasing subsection also strongly recommends using a series isolation resistor in conjunction with that filter capacitor. However, I also presume that you did not include this resistance as you are striving to minimize distortion and acknowledged that the INA240 should have some amount of output impedance as it does. If you would like the characteristic curve for output impedance, it may take some time before I can give that to you. If you would like more information on why the the output impedance matters for stability, please check the following links: https://e2e.ti.com/support/amplifiers/current-shunt-monitors/w/faq/3581.closed-loop-output-impedance-and-output-compensation-for-capacitive-load-stability, http://www.ti.com/lit/an/slya029/slya029.pdf
As for your schematic, we also have some concern over your REF pins as they appear to be floating with only capacitors tying them to the INA240 Out and Ground pins. Typically, we recommend one of the following setups for the REF pins:
Is there a particular reason for the configuration you chose for your reference pins?
