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I'm struggling a little bit here with the LM3880DBV circuit usage in a multi rail power supply circuit

So, here is my power supply circuit block schematic:

Blocks Schematic

And this is how I sequenced my circuit:

Sequence

My problem is I don't know where to put the sequencer circuit in my main power supply design schematic! As in the above schematic, it looks like the sequencer has to be connected to the end of the last output which is so confusing!!!! While in the LM3880DBV datasheet it seems to be placed before the generated outputs, as shown here:

image

The last output circuit:

last output

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Study your block diagram more closely (I've added explicit control lines to make it easier for you): -

enter image description here

As in the above schematic, it looks like the sequencer has to be connected to the end of the last output which is so confusing!

The lower output regulator is permanently activated hence, the voltage it generates is suitable for a supervisory controller like the LM3880. Just because it sits at the bottom of the diagram it doesn't mean it is somehow lower in status.

While in the LM3880DBV datasheet it seems to be placed before the generated outputs

It is - it controls supply 2 to 5 (not 6) via enable inputs. Just study your schematic.

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  • \$\begingroup\$ Awesome, very intuitive easy to follow answer! \$\endgroup\$ – user186623 Apr 24 at 11:33
  • \$\begingroup\$ last question, where I'm gonna connect the EN pin of the lm3880 with, or I just leave it unconnected? I attached the last output circuit! \$\endgroup\$ – user186623 Apr 24 at 11:45
  • \$\begingroup\$ The enable pin is crucial to how sequencing works and you should read section 7 of the LM3880 data sheet. I can't tell you how to connect it because it depends entirely on what your expectations and functionality are. \$\endgroup\$ – Andy aka Apr 24 at 12:07
  • \$\begingroup\$ got it! Thanks again, Andy! \$\endgroup\$ – user186623 Apr 24 at 13:16

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