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TMS320C5505: GPAINx Configuration

TI-CSC
Genius 12985 points
Part Number: TMS320C5505

Hello E2E Experts,

Good day.

I would like to use a voltage divider and monitor up to +5.5V ((30.1k/(100k+30.1k)) - 42.2 uA divider current), but if the ADC loads the divider too much, the reading will be inaccurate.

The question is, would this be fine on this configuration on GPAINx pins? There is no statement about the input current values for the GPAINx pins(powered by VDDA_ANA) – they are not in the datasheet.

Below is a schematic snippet.

Hope somebody would be able to help.

Regards, 

CSC

  • 0
    TI__Mastermind 18500 points

    Hi, 

    From the datasheet, it looks like the input resistance is around 1 Megohm minimum, so that would limit current to V_ADC/1Mohm, or ~ 1uA range. 

    With the SAR ADC inputs, you will need to respect the conversion timing and loading otherwise you might run into the conversion issues you suspect. Typically, SAR ADC are driven with a low impedance source providing voltage for the external sampling capacitor and this is matched with the internal device parasitics. 

    www.ti.com/.../sprufp1c.pdf

    Thank you,

    -Randy