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ADS7253: Some questions about I_REF_OUT

Hirotaka Matsumoto
Guru 27525 points
Part Number: ADS7253

Hi all

Would you mind if we ask ADS7253?

<Question1>
On the datasheet P9. there is the description about Reference output dc current (I_REFOUT)=2mA(typ).
It means that if I_REFOUT is within 2mA, V_REFOUT can keep 2.500V.
Is our recognition correct?
And why does this I_REFOUT=2mA mean typical value?(or Max value?)

<Question2>
Does (I_REFOUT)=2mA(typ) mean source and sink?(Or only source?)

<Question3>
Does the value (I_REFOUT)=2mA(typ) contain REFIO_A and REFIO_B?
So, is total 2mA(typ)?
Or is each value 2mA(typ)?

<Question4>
On the datasheet P9. there is the description about Internal reference output impedance RO=1Ω(Typ).
Could you let us know max value?

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Expert 3175 points
    Matsumoto-san,

    1) Yes, you are correct in your understanding of the I_REFOUT specification. The internal references are designed to output enough current to maintain an accurate reference voltage (2.5V for this part) throughout a conversion. This is a typical specification because the references were designed specifically to drive these ADCs. We don't measure the max/min output of the reference because as long as the ADC is providing accurate conversion we can infer that the reference is providing adequate current.

    2) Most references are designed to sink or source the stated current (2 mA for this device). I will confirm this and get back to you.

    3) The 2 mA specification is separate for the references. They both provide 2 mA.

    4) I need to see what data we have regarding the output impedance and will get back to you.
  • 0 in reply to Evan Sawyer
    Guru 27525 points

    Evan san

    Thank you for your reply!
    OK, we are waiting for the reply about (2) and (4).

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Evan Sawyer
    Guru 27525 points

    Evan san

    If it is possible, could you let us know when you get information about (2) and (4)?

    Kind regards,

    Hirotaka Matsumoto

  • 0 in reply to Hirotaka Matsumoto
    TI__Expert 3175 points
    Hi Matsumoto-san,

    Thanks for your patience. Below are answers for your remaining questions:

    2) The internal reference can source or sink the stated current (2 mA)

    4) We don't measure the max value of the output resistance, but the typical value is 0.5 ohms. 1 ohm is stated in the datasheet to provide a small amount of tolerance.
  • 0 in reply to Evan Sawyer
    Guru 27525 points

    Evan san

    Thank you so much for your reply!

    OK, we got it.

    Kind regards,

    Hirotaka Matsumoto