ADS1235: Handling unused input

Daisuke Higa

Part Number: ADS1235

Tool/software:

Hi support tam all.

The datasheet recommends connecting unused inputs to AVDD or AVDD/2, but if they are connected to GND, will the leakage current increase as stated in the datasheet?
Can you provide a technical explanation for why the leakage current increases?
My customer connected an unused input to GND without realizing the datasheet's advice, and would like to determine whether this needs to be corrected.

Best regards,

3 months ago

+1 Bryan Lizon86 3 months ago

TI__Guru 53666 points

Hi Daisuke Higa,

Yes, the leakage current can increase if you connect the inputs to ground. This is because of the FETs used to create the mux, at a basic level the off-state leakage of the FET that passes signals closer to ground is higher than that of the FET used to pass signals closer to AVDD.

As a wild guess I would think this increased leakage current is maybe 2-4x lower compared to the input current spec shown in the datasheet. But again that is just a guess

I'd recommend following the datasheet recommendations

-Bryan

0 Daisuke Higa 3 months ago in reply to Bryan Lizon86

Genius 4465 points

Bryan-san

Thank you for your prompt reply.

Your answer is very helpful to me.

Thanks.

0 Bryan Lizon86 3 months ago in reply to Daisuke Higa

TI__Guru 53666 points

Hi Daisuke Higa,

You are welcome

-Bryan

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ADS1235: Handling unused input