PMP23404: Schmatic SW 1 is empty pin?

Chen Alex1

Genius 3815 points

Part Number: PMP23404
Other Parts Discussed in Thread: LM5143-Q1

Tool/software:

hi Sir

May I know why the SW1 is empty pin?

thanks

over 1 year ago

0 Josh MANDELCORN over 1 year ago

TI__Prodigy 250 points

This SW1 pin is actually connected to Q3 drain / Q1 source in actual layout. The PMP23404 also incorrectly shows Vout (middle right edge of schematic) to be 3.3V, when it is actually 5V. On the other hand, the correct connection of U1 pin 28 FB1 to ground is shown to set Vout at 5V.

0 Chen Alex1 over 1 year ago in reply to Josh MANDELCORN

Genius 3815 points

You point out my second question, FB1 connected to VDDA by R16, 0 ohm to generate Vout1 in 3.3VDC and FB2 connected to GND to generate Vout2 in 5VDC. How could TI come out the test report by a reference design connected Vout1 & Vout2 together in different output voltage?

0 Darwin Fernandez over 1 year ago in reply to Chen Alex1

TI__Mastermind 41790 points

Hi Alex, thanks for catching these, the schematic will need to be updated. SW should be connected to the output filter. The picture you inserted above is slightly different than the schematic in the PMP23404. Both FB is connected to GND for 5V output.

https://www.ti.com/lit/df/tidmby8/tidmby8.pdf?ts=1719414916141

0 Josh MANDELCORN over 1 year ago in reply to Darwin Fernandez

TI__Prodigy 250 points

With single output 2-phase with the LM5143-Q1 Mode is always tied to VDDA and FB2 to ground:

From the LM5143-Q1 datasheet:

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PMP23404: Schmatic SW 1 is empty pin?