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2.5V Bias and protection in regards to digital ground | Cypress Semiconductor

2.5V Bias and protection in regards to digital ground

Summary: 1 Reply, Latest post by graa on 23 May 2011 10:02 AM PDT
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jsisson01's picture
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I'm in need of some suggestions for this issue. We are currently using the cy8c29866 for a thermocouple reader system.

It does its job great, but we have some issues with protection circuitry involved. The protection circuits we employ are to clamp or block 240vac. The problem is, due to the system using a 2.5bias analog ground, the protection circuits are rendered useless.

Is there a way that the psoc can read into the insamp without this 2.5v bias on the analog in?


PS, we are using the three op amp insamp module @ 48 gain and a del-sig @13bit

graa's picture
Cypress Employee
223 posts

Instead of bringing out AGND and connecting the signal w.r.t AGND, you can also use two resistors, one to VDD and one to thermocouple to bias the input to a higher level, while still connecting the thermocouple to the PSoC w.r.t VSS.  Check out the below blog article.


Measuring a Negative Voltage using PSoC1


Best Regards,


The PSoC Hacker

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