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ADS5281 - Single End input

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: ADS5281

Hello,

The customer use ADS5281 with Single End input.
And I got the customer schematics.

(1)
I couldn't find any document of Single end input of ADS5281...
Could you please let me know if there is any apprication note?
I found that the Application Report of SLAA416A. However there are the Differential Amp for Single ended imput...

(2)
Could you please kindly review the schematics ?
I can send the schematics if you contacting to the following e-mail address.

asaka-r@clv.macnica.co.jp

Best Regards,
Ryuji Asaka

  • 0
    TI__Mastermind 29220 points

    Hi,

    The ADS5281 does not support single ended inputs for the analog signal in.  The input signal must be fully differential and biased to the specified VCM voltage of 1.5V.

    That is, for a peak to peak fully differential input voltage of 2V, then each side of the differential voltage (at IN1P and IN1N for example) would have a 1V swing centered around 1.5V.  So at positive full scale the IN1P pin would be at 2.0V while the IN1N pin would be at 1.0V.   For negative full scale the IN1P pin would be at 1.0V while the IN1N pin would be at 2.0V.   Each input pin would always be in the range of VCM +/- 0.5V, or between 1.5V +/- 0.5V.   At all times the IN1N pin as far away from VCM as the IN1P pin is but in the opposite direction.

    The ADS5281 does not support tying the IN1N pin to VCM while the IN1P pin swings about that VCM.  That would not be fully differential.

    Regards,

    Richard P.