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TMS570LC4357: ADC analog voltage conversion

user6305667
Prodigy 230 points

Part Number: TMS570LC4357

Hello,

I am using the ADC of the TMS570LC4357 model. In the reference manual it is sais that both digital result and analog voltage are related by means of the following equation:

However, in the datasheet the values of the reference voltages High and Low are intervals (-0.1 - 0.1V for the Low and 3 - 5.25V for the High). Which values should I take in order to obtain the analog voltage of the signal? Is there a way of changing the reference voltage of the ADC?

Thank you in advance. Best regards,

Sergio

  • 0
    TI__Guru**** 200126 points

    Hello,

    The analog conversion range is determined by the reference voltages: ADREFHI and ADREFLO.

    ADREFHI is the top reference voltage and is the maximum analog voltage that can be converted. An analog input voltage equal to ADREFHI or higher results in an output code of 0x3FF for 10-bit resolution and 0xFFF for 12-bit resolution.

    ADREFLO is the bottom reference voltage and is the minimum analog voltage that can be converted. Applying an input voltage equal to ADREFLO or lower results in an output code of 0x000.

    Both ADREFHI and ADREFLO must be chosen not to exceed the analog power supplies: VCCAD and VSSAD, respectively.

    Normally, I use the same voltage level of VSSAD for ADREFLO, and same level of VCCAD for ADREFHI.

  • 0 in reply to QJ Wang
    Prodigy 230 points

    Thank you for your quick response QJ Wang, I really appreeciate it.

    So, we can conclude that I should use the minimum value of VSSAD (-0.1 V) and the maximum value of VCCAD (5.25 V) for ADREFLO and ADREFHI, respectively, right?