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Analog voltage range | Cypress Semiconductor

Analog voltage range

Summary: 5 Replies, Latest post by MrLogic on 01 Sep 2016 07:16 AM PDT
Verified Answers: 2
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user_151885's picture
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8 posts

I have a PSoC5 set up with some VDDIOx at 3.3V and some at 5V. My VDDA is also 5V. Let's say I connect an internal analog device, e.g. an OpAmp input or output to one GPIO in the 3.3V VDDIOx group. The question is: Is my voltage range on that pin 3.3V or 5V?

user_242978793's picture
User
1207 posts

+0 to 3.3 V as that is what the Gpio is set to.

user_151885's picture
User
8 posts

Sounds reasonable, but consider an OpAmp output that is routed to two pins on different VDDIO groups. Since the OpAmp has the output stage and the GPIO pin doesn't, it seems logical to me that both pins output the same voltage. Am I wrong? Why?

implicit's picture
User
28 posts

If I am reading the I/O system block diagram correctly then the routing doesn't work that way. Rather the digital output path still has clamping diodes connected for the VDDIO group, just with push/pull inactive.

user_1377889's picture
User
10120 posts

You are probably mixing analog and digital realms. The VDDA is common to the analog world which is separate from VDDD which is for the digital signals. VDDA must be the highest of all VDDs.

 

Bob

user_151885's picture
User
8 posts

Thanks for clarifying, Bob. I thought it was like that. I was just a little afraid that the pins had built in protection diodes to VDDIO also when used as an analog i/o which would limit the analog range to VDDIO. Obviously they haven't.

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