PSoC 4700S - CMOS 1.8V Input

[KaneTW]

I'm intending to use a CY8C4724FNI-S402T (due to availability + small package size) part for an application which needs to be powered by a 5V source and has a 1.8V LVCMOS input.

The TRM for the 4700S only mentions CMOS/LVTTL thresholds, but you can select "CMOS 1.8V" in PSoC Creator.

Does the 4700S series support 1.8V CMOS inputs?

[Sidramesh_S]

Hi @KaneTW ,

What is  the supply voltage you are setting on the system tab ? 

If you are giving the 5V in the VDDD then set in the system tabs as the supply voltage as 5V  then you can give CMOS input as 0.7*5 which is 3.5V. I have attached a snippet of GPIO DC Specifications from Datasheet kindly refer.

Also are you using the internal regulator or you are giving the 1.8V source directly, like the regulation is done by external circuitry ?

Thanks and regards,
Sidramesh.

[BiBi_1928986 · Accepted solution]

Hello.

I suggest you look at 4200M TRM and take note of the GPIO structure showing the GPIO input buffer with CMOS 1.8V selection mux.  When compared to 4700S TRM, the 4700S does not have this same input buffer structure.

Also, in 4700S Register TRM, the Port Configuration register does not show a CMOS 1.8V selection.

So, even though Creator allows you to select a CMOS 1.8V option, I suspect it won't work.  Maybe when you Build a Project, Creator will complain about the CMOS 1.8V.  And if Creator doesn't complain, I suspect if you test a build on real hardware, it doesn't work.

Creator is usually pretty good at "greying out" features that aren't available on a particular chip, but not always.

As it stands, unless Cypress/Infineon reply back with a different answer, it doesn't look like CMOS 1.8V is a guarantee.