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DS25BR120: Part to Part Skew Specification Clarification

Part Number: DS25BR120

Hi, 

From DS25BR120 datasheet (https://www.ti.com/lit/ds/symlink/ds25br120.pdf?ts=1626201909040&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDS25BR120) I see that for a given part, min Tpd is 350ps and max Tpd is 465ps. 

I also see that part-part skew is 80ps typical and 150ps max, and that "Part to Part Skew, is defined as the difference between the minimum and maximum specified differential propagation delays. This specification applies to devices at the same VCC and within 5°C of each other within the operating temperature range." 

The linked question states "DS25BR120 part to part skew refers to skew within positive and negative output of the DS25BR120 device. This normally shows itself as DCD or Duty Cycle Distortion or jitter." I think this is INCORRECT based on the datasheet description, and I think part to part skew refers to the max possible difference in Tpd between two DS25BR120 parts on a board that have the same VCC and are within 5C temperature. 

1. Can you please confirm that I am correct in this case and that linked question is not correct?

2. Can you provide an estimate for the minimum Tpd for the device? Surely the minimum Tpd must be less than the typical Tpd by at least 35ps because the max part to part skew (150ps) is LARGER than the difference between max and typical Tpd (465ps-350ps=115ps; 150-115=35) by 35 ps. 

Thanks!

  • Hi Steve,

    1). Your understanding is correct. Part to part skew is the skew or delay difference between differential pairs from different parts.

    2). Minimum Tpd has not been characterized but typically it is within 25 to 30% of the nominal value(~260ps).

    Regards ,, Nasser