Maximum allowed voltage on STM32H755XIH3 adc pin

[JYada.1]

Hello Team,

we are using the STM32H755XIH3 for our new development. in the datasheet there it mentioned the maximum allowed voltage on input pin is 4V. somewhere its mentioned that the allowed voltage is of 3.6V.

please let us know what will be the maximum allowed voltage at which the controllers pins were protected against the maximum voltage.

awaiting your reply !

Thanks  

[Uwe Bonnes]

There is a difference between "6.2 Absolute maximum ratings" and "6.3.1 General operating conditions"

[FBL]

Hello @JYada.1 

The maximum allowed voltage for safe and reliable operation is the one specified under General Operating Conditions, which is 3.6V. This is the voltage level at which the microcontroller is designed to operate normally. However, the Absolute Maximum Ratings are the stress limits beyond which the service life of the microcontroller may be compromised.

[AScha.3]

Hi,

you ask for "maximum allowed voltage"  on ADC input - what is "allowed" here for you ?

- chip just not killed ?    -> max. VDD (=VDDA) + 0,3V  ; 3,6V at 3,3VDD.

- ADC still working ?  -> VDDA (=VREF) ; 3,3V at 3,3 VDD(=VDDA).

[JYada.1]

Hello @AScha.3 ,

Thanks for the reply !!

i am using PC2,PC3 and PA2 pins which are FT_xxx Pins (Five volt tolerant pin) for that in Table 20:Absolute maximum rating they said that max voltage for this pins will be Min(VDD, VDDA,VDD33USB, VBAT) + 4.0 and as for ADC the supply is VDDA, so the min of VDDA in Table 23: General Operating conditions will be 1.62 V so as per Absolute maximum rating table it will be (1.62 V+ 4.0 V= 5.62 V) is this correct ? or i am missing something ?

[AScha.3]

Hi,

NO !

If you select "analog" function on a pin, max. VDDA is the max. value for this pin then.

(You switching the pin multiplexer from digital to analog and so only analog min. or max. values apply.)

So for ADC the max. usable input is Vin = VREF , the maximum without destruction is up to 3.6 V .

(Any "5V-tolerant" is only for pin in digital input mode, so it will survive (digital) signals up to 5.5 V .)

[JYada.1]

Hello,

i am reading analog value until 3V only , this 5.62 V i am considering for protection purpose. because one my condition the pin will getting 4.165 V as maximum so i just need to check whether my pin can handle this much voltage without damaging, and this will not be for constant operation this will be for shorter duration.  

[AScha.3]

No.  3.6V is max. analog Vin at 3v3 VDDA.