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SK.7
SK.7
Associate
November 26, 2018
Question

STM32F407IGT6 ADC Input Range

Hello,

Am using STM32F407IGT6 in my design. I power the VDD, VDDA & VBAT from 3.3V.

I use an external voltage reference using LM4121AIM5-ADJ which generates 3V from 3.3V input.

When I use this external reference of 3V as VREF+, I would like to understand whether the ADC input range Vain can still be in the range of 0 to VDDA (i.e., 3.3V). Please advice whether the ADC input upto 3.3V is fine or will it cause any issue/damage to the STM32 MCU when VREF+ is 3V.

Looking forward for your immediate support in this regard.

Regards,

Sridevi

    This topic has been closed for replies.

    2 replies

    waclawek.jan
    waclawek.jan
    Super User
    November 26, 2018

    As long as you are within the voltage given by the Absolute Maximum chapter in datasheet (sidenote: even Ft-type pins are *not* 5V tolerant when connected to ADC; yet up to 4.0V should not still not cause damage) you should be fine. The result of conversion will saturate at 1023 at VREF and above, but you probably expect that.

    JW

    SK.7
    SK.7Author
    Associate
    November 30, 2018

    Hi JW,

    Yes I understand that the result of conversion will saturate.

    Thank you for the clarification.

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