• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 30 subscribers
  • Views 223 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.

LM48511: Grounding when using external boost power supply

Matt Mozur
Prodigy 30 points
Part Number: LM48511

I am planning on using an external power supply for system architectural reasons.  In review of the data sheet, I see that LSGND is the H-bridge ground and REGGND is the ground for the boost supply.

What is the recommended scheme for grounding when using an external boost power source. I am thinking that REGGND is not going to be carrying much, if any, current and I should tie the external power source ground directly to the LSGND pins to keep the loop tight.  I would connect the REGGND and Signal Ground pins along with LSGND in a star, as the datasheet recommends.

In a related question, the application guide shows a 10uF bulk capacitor connected to the Vdd supply input and the inductor..  There are also several 1 uF capacitors on Vdd.  With an eternal boost, can the 10uF capacitor be moved to the external regulator circuit?

Thanks,

Matt

  • 0
    TI__Guru* 84915 points

    Hi, Matt,

    Welcome to E2E and thank you for your interest in our products!

    You are right in all your comments about the LSGND ground pin connection. We recommend to connect the ground in a star connection. LSGND carries more current than any other pin.

    Regarding the 10uF capacitor, this is required in order to serve as an energy reservoir. It should be placed as close as possible to the VDD pin, not to the regulator circuit.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 30 points

    Thanks, Luis.  I'll leave the 10 uF capacitor on Vdd,   I'll also leave REGGND connected to the star ground since I suspect it would not be a good idea to float the regulator section, even if I am not using it.

    /SD_BOOST will connected to ground, so can I leave FB, FB_GND1, and FB_GND0 unconnected?  Or, should I connect all three to ground?

    Thanks,

    Matt

  • 0 in reply to Matt Mozur
    TI__Guru* 84915 points

    Hi, Matt,

    Both FB_GND switches can be left open as mentioned in section 7.3.5 of datasheet. This practice reduces shutdown current.

    Best regards,
    Luis Fernando Rodríguez S.