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TMS570LS1224: ADC how to config to 0-5V input?

Joe X20
Intellectual 430 points
Part Number: TMS570LS1224

Hi, All.

  I check the data sheet. The max reference ADC input is Vad-ref-hi, and max of Vad-ref-hi is the Vccad. And the Vccad is the pin on the CPU. I think for this launchpad, it is connect to 3.3V in default. But now, I want to read 0 - 5 V analog input, is this possible? and how?

  • 0
    TI__Guru**** 196206 points
    Hi Joe,

    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 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 equal to ADREFLO 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.

    So if you want to read 0~5V analog input, the VCCAD should be 5V, and ADREFHI is 5V, and ADREFLO is GND.