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TPS74801-Q1: Difference between TPS74801DRCR and TPS74801TDRCRQ1

Part Number: TPS74801-Q1

Hi team,

My customer has been using TPS74801DRCR. But recently, they consider to replace it to TPS74801TDRCRQ1 in order to prevent delivery shortage.

Then, they're asking some questions.

  1. Do those devices use same chip(die) inside the package?
  2. Are difference only temp spec and test condition/item between Q1 and non-Q1?
  3. Although these device adopt same package(DRC), RJA is different. 
    Why is RJA different? Is it just error of datasheet?
  4. Why Ta range is different between DRC(up to 105C) and RGW(up to 125C)?
    Is this because of larger thermal resistance of DRC?
  5. As for  thermal resistance of DRC package, θJCtop of Q1(78℃/W) deteriorates from non-Q1(50.3℃/W).
    But meanwhile, ψ of Q1 is same as  non-Q1. Does it mean thermal performance in case of actual board is same?

Best regards,

Shota Mago

  • Hi Mago-san,

    I've added my answers below

    1. Do those devices use same chip(die) inside the package?
      1. Yes the same chip is used, the automotive device goes through a special Q1 flow but the chip is the same. 
    2. Are difference only temp spec and test condition/item between Q1 and non-Q1?
      1. The Q1 devices goes through an Automotive qualified manufacturing flow in order to meet the increased requirements in order to maintain AEC-Q1 qualification. 
    3. Although these device adopt same package(DRC), RJA is different. 
      Why is RJA different? Is it just error of datasheet?
      1. Automotive devices may use slightly different BOM in order to maintain AEC-Q1 qualification. These slight changes in the BOM can result in slightly different thermal metrics. 
    4. Why Ta range is different between DRC(up to 105C) and RGW(up to 125C)?
      Is this because of larger thermal resistance of DRC?
      1. No, listing min/max Ta for LDOs was an old practice which has been eliminated since the important temperature to be aware of is actually the junction temperature (Tj) with little or not power dissipation the max Ta can equal the max Tj. The RGW package was released several years after the DRC package and what likely happened is that we wanted to give the most flexibility to our customers so listed the RGW Ta as 125C but did not want to cause a PCN to be generated and so left the Ta for the DRC package as it had been originally published. 
    5. As for  thermal resistance of DRC package, θJCtop of Q1(78℃/W) deteriorates from non-Q1(50.3℃/W).
      But meanwhile, ψ of Q1 is same as  non-Q1. Does it mean thermal performance in case of actual board is same?
      1. The thermal performance will be very similar when placed on the same board. I did find updated thermal results for the Q1 device which were performed in 2016 and it shows slightly higher but similar values as the non-Q1. See the table below.  

    Thermal results TPS74801TDRCRQ1

    Theta JA

    47.9

    Theta JC, top 

    46.5

    Theta JB

    22.7

    Psi JT

    1.0

    Psi JB

    22.8

    Theta JC, bottom 

    5.7
  • Hi Kyle-san,

    Thank you so much for your detailed answer!

    Let me confirm thermal performance of TPS74801TDRCRQ1.

    You mentioned above thermal performance were performed in 2016. Meanwhile, latest revision of datasheet of TPS74801-Q1 is 2013 and it has not been updated to result of 2016.

    Which data should we trust?

    Best regards,

    Shota Mago