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TPS22998: Relation for VIN and VBIAS

Satoshi
Guru 19485 points
Part Number: TPS22998

I think that many other Load Switch are decided maximum operating Vin range: Vin<VBIAS.  

But TPS22998 is described Vin operating range: 0.2~5.5V, not to Vin<VBIAS.

Please let me know why Vin range independent from VBIAS.

Best regards,

Satoshi

  • 0
    TI__Genius 14130 points

    Hi Satoshi-san, 

    TI's recommendation is to keep the VIN voltage below or equal to VBIAS. All the electrical tables focus on VBIAS >= VIN since the on-resistance gets significantly higher once VIN exceeds VBIAS. VIN can also be tied to the VBIAS supply if it is greater than 2.2V.

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    Guru 19485 points

    Hi Elizabeth,

    Thank you for reply,

    I understood the relation for VIN and VBIAS.

    Please let me know the background for TPS22998 only not described the Vin<VBIAS.

    I guess that on-resistance gets significantly higher once VIN exceeds VBIAS, but suppress lower than the other Load Switch, correct?

    If possible, would you give me the on-resistance specification for Vin>VBIAS condition?

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 14130 points

    Hi Satoshi-san, 

    Thank you for your question; I understand the need for clarification, and we are working to clarify this in the datasheet. 

    There is no specific reason we have the Vin recommended operating range as 0.2V to 5.5V rather than 0.2V to Vbias for the TPS22998. 

    Although we can operate in the 0.2V to 5.5V range, we would still recommend 0.2V to Vbias, and are we are working to make that more clear in the datasheet. 

    To be clear, there is no distinction in the TPS22998 which would results in a lower than normal Ron at Vin>Vbias and we do not have any data for Ron at the Vin>Vbias condition. 

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    Guru 19485 points

    Hi Elizabeth

    Thank you for reply,

    One of customer's circuit is need Vin: 5V and VBIAS: 3.3V. (TPS22998 is only matched from 10A and lead time)


    Is there reference test data about on-resistance for above VIN and VBIAS condition?

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 14130 points

    Hi Satoshi-san, 

    We do not have any reference test data for on-resistance when Vbias < Vin. 

    Could the customer boost the Vbias signal to 5V? Or can they tie Vbias and Vin together?

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    Guru 19485 points

    Hi Elizabeth

    Thank you for reply,

    I understood that you have not reference data. 

    Customer is considering to change the VBIAS: 3.3V to 5V on their board, but whether VBIAS can change has not been decided yet.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 14130 points

    Hi Satoshi-san, 

    Understood; The best path forward is to change Vbias to 5V or tie Vin and Vbias together for the Ron to reflect what has been provided in the datasheet and shown below: 

    Operation outside of Vin<Vbias could result in higher Ron than documented above. 

    *edit: previous notes below were for tying Vbias to ON not tying Vin to Vbias. Since these comments are irrelevant, they have been deleted. 

    Best Regards, 

    Elizabeth 

  • 0 in reply to Elizabeth Higgins
    Guru 19485 points

    Hi Elizabeth

    Thank you for advice,

    I will measure the TPS22998EVM and confirm the Ron.

    Maybe last question, what is the gate voltage for internal N-ch MOSFET?

    This specification is need for measure and confirming.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Genius 14130 points

    Hi Satoshi-san, 

    The internal gate voltage is not a value we provide. 

    The Ron can be measured using the TPS22998EVM User's guide and the diagram below: 

    https://www.ti.com/lit/ug/slvucb6/slvucb6.pdf?ts=1664981565410&ref_url=https%253A%252F%252Fwww.google.com%252F

    Best Regards, 

    Elizabeth