• State Resolved
  • Locked Locked
  • Replies 11 replies
  • Subscribers 63 subscribers
  • Views 1255 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Question about LM10504 Reset function

Go
Genius 4155 points
Other Parts Discussed in Thread: LM10504, LM10506

Hi,

I'd like to ask about LM10504 RESET function as follows,

1. if we don't use RESET function, Is it Ok to keep the RESET pin open?

   (Because the RESET pin has internal pull-up resistor.)

2. Is there any other reason that not listed below to force LM10504 into the reset state?

 ・RESET pin is pulled low

 ・VIN UVLO is detected

 ・VIN OVLO is detected

 ・Thermal Shutdown is detected

Thanks,

Go

,

  • 0
    TI__Genius 10095 points

    I am forwarding this to the appropriate engineers.  It is not a product covered by simple switcher.

    Regards,

    Marc

  • 0
    TI__Intellectual 770 points

    Hello,

    1)     It is okay to keep the pin floating. No issues have been observed in this case.

    2)     Regarding the second question, are you asking of any other functionality that can cause the part to RESET;  apart from ones in the list?  If so, another one would be to force a buck out of regulation such as short-circuit, page 23 in the LM10504 datasheet covers it:

     “When any of the Buck outputs are taken out of regulation (below 85% of the output level) the device will start a shutdown sequence and all other outputs will switch off normally.  The device will restart when the forced out-of-regulation condition is removed.”

    Hope this answers your questions.

    Regards,

    Doyel

  • 0 in reply to Doyel Ghosh
    Genius 4155 points

    Hi, Doyel

    Thank you for your comment.

    I'd like to ask some additional question about LM!0504 as follows.

    1. What is the value of internal pull-up resistor of LM10504 reset Pin?

    2. How about the nternal pull-up resistor of LM10506? same as LM10504?

    Regards,

    Go

  • 0 in reply to Go
    TI__Intellectual 770 points

    Hi Go

    1) I will get back to you regarding the exact value of the internal pull-up resistor.

    2) Yes, the internal pull-up resistor of the LM10506 is the same as that of LM10504.

     

    Regards,

    Doyel

     

  • 0 in reply to Go
    TI__Intellectual 770 points

    Hello,

    The Reset pin of LM10504/06 has an internal pull up resistor of 3M

    Regards,

    Doyel

  • 0 in reply to Doyel Ghosh
    Genius 4155 points

    Hi, Doyel

    Thank you for your continued support.

    According to your answer about LM10504/06 internal pull up resistor,

    LM10504/06 have an same internal pull up resistor (3MΩ typ.)

    and you also answered before that it’s OK to keep the LM10504 RESET pin open

    if we won't use RESET function.

    but in the LM10506 D/S , it says that LM10506 RESET pin should be tied to VIN_IO if unused.

    What is the reason of this difference?

    Is there any other difference between LM10504 and LM10506?

    Thanks

    Go

  • 0 in reply to Go
    TI__Intellectual 770 points

    Hi Go,

    The datasheet table in LM10506 for unused pins, is a recommendation only. Because this particular pin has an internal pull-up resistor anyway, it is okay to keep it floating.

    The bucks of LM10504 can drive higher load currents as compared to LM10506. Certain pin-names are different, but both parts are similar in terms of their functionalities.

    Best Regards,

    Doyel

     

     

  • 0 in reply to Doyel Ghosh
    Genius 4155 points

    Hi,Doyel

    Thank you for your support,

    I'm really sorry to ask many question about LM10504/LM10506, 

    but could you tell me about following things?

    1. Internal pull down resistor value of LM10504 DevSLP Pin

    2. Internal pull down resistor value of LM10506 STANDBY Pin

    Thanks,

    Go

  • 0 in reply to Go
    TI__Intellectual 770 points

    Hi Go,

    The pull-down resistors of both LM10506 and LM10504 Devsleep/Standby Pin is 3MΩ. .

    Best Regards,

    Doyel

  • 0 in reply to Doyel Ghosh
    Genius 4155 points

    Hi, Doyel

    Thank you for your support.

    Could I ask some advice about LM10504 behavior?

    Regarding the attached waveform, 

    The RESET pin voltage is down suddenly approximately 1 sec later after power up,

    and getting lower and finally reach 540mV.

    (Reset pin is OPEN and VDD_IO is powered from Buck2_OUT.)

    Is this RESET pin behavior normal for LM10504?

    Thanks

    Go

  • 0 in reply to Go
    TI__Intellectual 770 points

    Hi Go,

    I've replicated the experiment, however I couldn't see the dip in the RESET pin as shown in the plot. Please can you provide a few more information:

    1) Are any of the Bucks, or the RESET pin, loaded?

    2) What is the value of the Vin?

    3) Are you using the LM10504EVM ; if so, are you keeping it connected through USB?

    4) Have you tried replicating the experiment with VIN_IO connected to Vin/Separate supply? Please can you also give me the status of the STANDBY pin in your experiment?

     

    Best Regards,

    Doyel