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LM48511 Use Case of either the Regulator Feedback Network of FB_GND0 and FB_GND1 only

Sadanori Kato
Guru 36490 points
Other Parts Discussed in Thread: LM48511

Hi,

Could you please give us your advice since we would like to use LM48511 by connecting the FB_SEL pin to either of VDD and GND ?
Is it possible to make the FB_GND1 pin floating if the FB_SEL pin is connected to GND since we would like to decrease the mounted parts ?
In addition, we believe that the logic of FB_SEL has the dead zone internally when LM48511 is applied the power supply voltage slowly(the power supply voltage is a low level).
So, which is FB_GND0 and FB_GND1 selected preferentially in that case if FB_SEL is connected to GND ?
Is our understanding correct although we believe that the current path of FB_GND0 is selected as the initial value ?

Best Regards,
Kato

  • 0
    TI__Guru 52115 points
    Hi Kato,

    I will try to help you with this issue.

    Andy
  • 0 in reply to Andy Liu (BMS)
    Guru 36490 points

    Hi Andy-san,

    Thank you for your reply.
    I am looking forward to hearing from you.

    Best Regards,
    Kato

  • 0 in reply to Sadanori Kato
    TI__Guru 52115 points
    Hi Kato,

    I heard from Naokawa-san that you already got some answers from him. I put some comments below to close this post.

    a) Is it possible to make the FB_GND1 pin floating if the FB_SEL pin is connected to GND since we would like to decrease the mounted parts ?
    Comment : Yes, it is.

    b) In addition, we believe that the logic of FB_SEL has the dead zone internally when LM48511 is applied the power supply voltage slowly(the power supply voltage is a low level). So, which is FB_GND0 and FB_GND1 selected preferentially in that case ? Is our understanding correct although we believe that the current path of FB_GND0 is selected as the initial value ?
    Comment : There is no answer from the datasheet. My colleague had a try with Vdd's rising time 1V/sec and no improper behavior was found.

    Andy
  • 0 in reply to Andy Liu (BMS)
    Guru 36490 points

    Hi Andy-san,

    Thank you for your reply.
    As you said, I have discussed with our customers based on the advice from Naokawa-san, this issue has been closed.

    Best Regards,
    Kato