STM32U3: 3V3 tolerant GPIO at 1V8 supply ?

[FERAMUZ]

Hi,

I am using STM32U385CGU6 with 1.8V supply. My GSM peripheral using the 3.3V Uart port for a dedicated time (2sec) then turn back to 1.8V level of UART.  

Could you offer 3.3V tolerant pin? I am using PA8 to communicate with GSM module.

thank you & best regards,

feramuz karşil

[mƎALLEm]

Hello,

From the datasheet (DS14830 - Rev 3) / Table 27. General operating conditions

That depends on what you are using as power supply.

[waclawek.jan · Accepted solution]

Look at pin/ball definitions table in Datasheet, that lists all pins together with their input/output structure.

Now look at General operating conditions table, that gives the permissible range of voltages for each type of pin. For TT_xx pins, it's generally up to its VDDIO (which except some PGx pins and USB pins is identical to VDD) supply voltage; for FT_xx pins ("five-volt tolerant"), it's up generally up to VDDIO+3.6V or 5.5V, whichever is less.

PA8 is listed as FT_h, so it should be OK if it is turned to input and 3.3V is applied to it. It won't be able to source 3.3V when VDD is 1.8V, though.

JW

[FERAMUZ]

Hi JW,

thank you for your feedback.

best regards,