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ADS5263: External Internal Voltage Reference Mode

Gruffalo
Intellectual 310 points
Part Number: ADS5263

Tool/software:

Dear Sir or Madam,

 I would like to operate the ADC in external voltage reference mode. 

I have connected pin 56 to GND however I still see the VCM pin being a source of 1.5V. Is this expected? I would expect the internal common mode 1.5 V to be shut down when the pin is connected to GND.  

Best.

  • 0
    TI__Expert 6875 points

    Hi,

    When you pull pin56 to gnd the VCM pin acts as input pin and you need to provide external reference voltage. Lets say if you force 1.48 V you should be able to measure that .

  • 0 in reply to Sachin H K
    Intellectual 310 points

    Dear Sachin,

    thank you for the fast reply.

     so the two sources will not "collide" ? Can you please confirm that forcing an external voltage (eventhough some internal source already drives this pin since 1.5V is measured) is the correct way to operate in this mode?

    Best

  • +1 in reply to Gruffalo
    TI__Expert 6875 points

    Hi,

    If  pin56 is gnd then VCM acts as an input pin. The user is expected to force the reference voltage they want . In this mode VCM is high impedance and without external forcing voltage its voltage is not defined or weakly defined . So there is no issue to force external voltage in this mode.