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TPS63021: The maximum sink current of the PG pin.

Shinichi Inoue
Guru 20896 points
Part Number: TPS63021

Dear Specialists,

MY customer wants to know about the maximum sink current of the PG pin.

I would be grateful if you could advise.

---

①I would like to know about the maximum sink current of the PG pin.

The value of the pull-up resistor cannot be determined because it is not mentioned in the data sheet.

The pull-up resistor for the PG pin is 1MΩ in the Typical Application circuit diagram.

In the "PG output low voltage" item, the operating conditions are "VOUT = 3.3 V, IPGL = 10 μA".

For these reasons, we believe that it is necessary to select a MΩ level pull-up resistor.

Could you please let us know  the maximum sink current of the PG pin.

② Regarding the voltage applied to the PG terminal, the data sheet states that the maximum rating is 7V, so we have determined that there is no problem with pulling it up to 5V.

Is it possible？

Just to make sure, I would like to check if there is no problem even if I apply 5V continuously.

---

I appreciate your great help in advance.

Best regards,

Shinichi

  • +1
    TI__Mastermind 29010 points

    Hi Shinichi,

    For maximum sink current, you can just take the leakage current in EC table as ref. which is 0.1uA max. MΩ level is not necessary for PG.

    Fot voltage applied, yes, a  continiously 5V is acceptable.

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Guru 20896 points

    Hi Tao,

    Thank you for your quick reply.

    I understand Maxim current is 0.1uA .

    At this time continuous current at 5V is acceptable.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi 

  • 0 in reply to Shinichi Inoue
    Guru 20896 points

    Hi Tao,

    I found one question.

    As you mentioned Maximum current is 0.1uA.

    5V/0.1uA=50Mohm 

    This means pull up resistor is more than 50Mohm

    It is quite different from 1Mohm in the datasheet.

    3.3V/1Mohm =3.3uA

    How should I understand？

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 29010 points

    Hi  Shinichi,

    Defination of leakage current of PG is the current measured when FET internal is off and a voltage applied at this pin, so, it has nothing to do with your pull up resister.

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Guru 20896 points

    Hi Tao,

    The customer wants to know the maximum sink current value in order to decide what ohm to use for the pull-up resistor.

    Could you please let me know maximum sink current of PG pin?

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 29010 points

    Hi   Shinichi,

    If my understanding is correct, the maximum resistance of FET internal when FET on is 0.4V/10uA, which is 40K.

    The actual sink current of PG is depend on your pull up resister. if this pull up resister is connected to output, then actual sink current should be Vout/(Rpull+RFet_pg).

    Assuming customer want know the maximum sink current just want to make sure the low voltage can meet their requirment under certain pull up resister. then, i think use maximum 40K resister of internal FET to evalute is enough.

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Guru 20896 points

    Hi Tao,

    Thank you for your reply.

    General-purpose comparators have a sink current (IOL) specification.

    In the case of TPS63021 as well, the customer wants to refer to the sink current (IOL) specifications and decide on the pull-up resistor.

    Is there no sink current specification for the TPS63021 PG?

    On the other hand, is TPS63021 possible to connect the PG pin and 5V directly and no damage?

    Could you please advise?

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 29010 points

    Hi  Shinichi,

    As mentioned, the sink current is depend on your actual application. EX, the sink current is very different with a different pull up resister connected to Vout.

    With a 10MΩ resister， the sink current of PG is close to Vout/10M， with a 100k resister,  the sink current is Vout/(100k+RFet_pg).

    Also. it is not allowed to connect the PG pin with a 5V source directly, without a pull up resister.

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Guru 20896 points

    Hi Tao,

    Thank you for your reply.

    In case of TPS63021, pull up resistor is limited by inside FET (40kmax/4ktyp).

    The pull-up resistor ensures that the L level voltage matches the L level on the receiving side.

    If VOL0.4V and 40kΩ, the pull-up resistance value will be 60k.

    The current value at this time is 5V/(60k+40k)=50μA

    Even with the typical value of 4kΩ, 5V/(60k+4k) = 78μA

    These values will not damage the TPS63021.

    Are these understanding correct?

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • 0 in reply to Shinichi Inoue
    TI__Mastermind 29010 points

    Hi  Shinichi,

    In your pull-up resistance calculation,  voltage is assumed 1V, and it is not match with your actual application, right?

    Regards

    Tao

  • +1 in reply to Tao Zhang
    Guru 20896 points

    Hi Tao,

    Thank you for pointing out.

    I calculated incorrectly.

    Pull-up voltage is 5V.

    The pull-up resistor for VOL to be 0.4V was 460kΩ.

    In this case, the current (IoL) 

    5×40k/(40k+460k)=10μA

    When the internal FET impedance is 4k,

    IoL is 5×4k/(4k+460k)=10.8μA

    The application is transport system

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi

  • +1 in reply to Shinichi Inoue
    TI__Mastermind 29010 points

    Hi  Shinichi,

    You are welcome. calculation is correct now.

    Regards

    Tao

  • 0 in reply to Tao Zhang
    Guru 20896 points

    Hi Tao,

    Thank you for your reply.

    The calculated value is IoL maximun, which is 10.8uA.

    This value is considerably small and not considered to be a value that would damage the internal FET.

    I'll share the information with the customer.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi