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UCC27611: LDO function limitations

Lionel FORO
Prodigy 10 points
Part Number: UCC27611

Tool/software:

Dear all,

We are currently performing a characterization of the LDO function of the UCC27611 and we have the following questionings:

What are the user limitations of LDO function ?
Have you done an electrical characterisation which includes the power that could be managed by this function ?
The idea is to have an output current (Ir) vs Supply voltage (VDD) curve.
Do you have some recommendations as a Safe Operating Area (SOA) ?
Could you confirm to us that the LDO could provide a current of 50 mA up to VDD = 18V ?
Otherwise, with VDD equal to 18V, what is the max output current that can provide the LDO ?
Amongst its subfunctions, do you include a current limiter or thermal overload protection ?
Thanks for your reply.

Best regards,
Lionel FORO
  • 0
    TI__Prodigy 710 points

    Hello Lionel,

    1. What are the user limitations of LDO function?
    VREF is meant to provide a well-regulated voltage to drive a GaN FET, and the pin is not designed to drive any external components. 
    2. Have you done an electrical characterization which includes the power that could be managed by this function?
    The characterization from the datasheet was done using only the internal load, as that is its intended purpose. 
    3. Do you have some recommendations as a Safe Operating Area (SOA)?
    We don't have any data/recommendations available.
    4. Could you confirm to us that the LDO could provide a current of 50 mA up to VDD = 18V?
    The current on this pin is spec'd only for 12V, we do not have data available across different VDDs.
    5. Do you include a current limiter or thermal overload protection?
    There is no overtemperature or overcurrent protection on this device.
    Thanks,
    Annabelle
     
  • 0 in reply to Annabelle Alemand
    Prodigy 10 points

    Hi Annabelle,

    Thanks for your reply.

    Could you share with us the life test conditions of the device? 

    Was it performed at maximum rated VDD voltage?

    Best regards,

    Lionel

  • 0 in reply to Lionel FORO
    TI__Prodigy 710 points

    Hi Lionel,

    You can find lifetime tests for a device on TI.com by going to Quality & Reliability > Qualification Summary and then inputting the desired OPN. (link here: https://www.ti.com/qualificationsummary/qualsumm/home?actionId=2800) 

    I am getting in contact with our Product Engineers to determine what VDD is used for the tests, and will get back to you when that information is available.

    Thanks,

    Annabelle

  • 0 in reply to Annabelle Alemand
    TI__Prodigy 710 points

    Hi Lionel,

    Yes, the life test was performed at the maximum recommended VDD for this device, which is 18V.

    Thanks,

    Annabelle

  • 0 in reply to Annabelle Alemand
    Prodigy 10 points

    Hello Annabelle,

    Thanks for the quick reply.

    Can we assume that the life test was performed without any load on the LDO?

    I understood from from your fisrt reply that the VREF is not designed to drive any external components.

    However, a load regulation is specified in the datasheet for the VREF. Which is a little bit confusing for us.

    Can you clarify how this assessment of the load regulation is performed?

    Thanks,

    Lionel

  • 0 in reply to Lionel FORO
    TI__Prodigy 710 points

    Hi Lionel,

    For the LDO load, let me discuss this with my team. I will get back to you soon.

    VREF load regulation is the measure of the variation in VREF as a function of load current and is specified either as a percentage or in parts-per-million per milliamp (ppm/mA). It is calculated by dividing the relative change in VREF at minimum and maximum load currents by the range of the load current. You can find more information in this white paper https://www.ti.com/lit/wp/slpy003a/slpy003a.pdf?ts=1756479675474&ref_url=https%253A%252F%252Fwww.google.com%252F 

    Annabelle

  • 0 in reply to Annabelle Alemand
    TI__Prodigy 710 points

    Hi Lionel, 

    Thank you for your patience. I am still working on getting the answer about the LDO load for you. I will let you know as soon as possible.

    Thanks,

    Annabelle

  • 0 in reply to Annabelle Alemand
    Prodigy 10 points

    Hello Annabelle,

    Thank you for the update.

    Are you authorized by the meantime to share the bias configuration of the life test?

    Thanks,

    Lionel

  • 0 in reply to Annabelle Alemand
    Prodigy 10 points

    Hello Annabelle,

    Thank you for the update.

    Are you authorized by the meantime to share the bias configuration of the life test?

    Thanks,

    Lionel

  • 0 in reply to Lionel FORO
    TI__Prodigy 710 points

    Hi Lionel, 

    I am still working on getting the exact conditions for you, but according to JEDEC standard JESD22-A108 (HTOL life test), the device should be tested at the maximum recommended operating temperature (in this case 140C), the max recommended VDD (in this case 18V), and the output stage is actively driving a load to replicate real-life conditions. This is why I believe there would be a resistive load on the internal LDO so that it is continually sourcing/sinking current.

    You can sign up for a JEDEC account and find a PDF explaining the general set up for HTOL. Unfortunately, I cannot post it here.

    Once I confirm this information with our Product Engineers, I will get back to you. Thank you for you patience!

    Thanks,

    Annabelle

  • 0 in reply to Annabelle Alemand
    TI__Prodigy 710 points

    Hi Lionel,

    I have not been able to get the specific bias configuration or LDO load setup for HTOL test for UCC27611. This is an older part that RTM'd in 2012, and there were no details on the load/bias setup of the qualification tests, only the passing results. I appreciate your patience while I investigated this matter, and apologize that I cannot find more details for you. 

    Thanks,

    Annabelle