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SM73201: ADC SM73201 Clarification

Claudio Maria Lamacchia
Prodigy 100 points
Part Number: SM73201

Hi,

i’m using the ADC SM73201 as in the picture below.

I need some clarification:

  • the VIO voltage is referred only at the SPI signals and it doesn’t affect the voltage input? So if I connect the 3.3V voltage, the SPI signals work at 3.3V. Is it right?

  • I have a differential signal, whose each signal as a voltage range between 0.5V and 4.5V. In other words I have a maximum differential signal of 4V and an input common mode of 2.5V. If I use a VREF=4.096V and a VA=5V, it should work well since the single input voltage is referred to VA and the differential value is referred to VREF?

  • 0
    TI__Mastermind 46200 points

    Hello Claudio,

    1.  Correct, the voltage on VIO sets the logic voltage levels for /CS, DOUT, and SCLK.  The input voltage on each input with respect to GND is set by the voltage on VA.  In the case of VA=5V, the input range is 0 to 5V.  The differential voltage (measured from +IN to -IN) is set by the voltage on VREF.

    2.  Yes, you are correct.  In the case of VA=5V and Vref=4.096V, each input can range for 0V to 5V.  The difference measured between the inputs will be in the range of -4.096V to +4.096V.  Assuming a common mode voltage of 2.5V

    a) -4V differential input, +IN=0.5V and -IN=4.5V.

    b) +4V differential input, +IN=4.5V and -IN=0.5V.

    Regards,
    Keith Nicholas
    Precision ADC Applications