Duet 3 Power Supplies

DocTrucker

If the Duet is setup to power the Raspberry Pi over the ribbon connection what is the total 5V current that can be drawn from off the Duet? Are we closer to getting the power requirements of the board detailed on wiki?

Guess the external 5V connector can still be used instead of internal VIN to 5V regulator if things are getting a little close?

A post from the octopi developer on Twitter suggested the Raspberry Pi should have a 3A supply. Not sure what load the 7" touch screen HDMI screens take yet, but will need a little more headroom for that.

Danal

I don't have math/measurements; I do have a config that works:

Duet3 <Ribbon> RPi 4B+ w/4Gig Ram
Jumpers at factory default, Power Pi from Duet

RPi has USB to:

The same Duet3 (for Bossa, if needed) should be net zero power
A 7" touchscreen w/backlight
A USB camera (experimenting, have had microscope/w build in LED lighting; currently Logitech C270)

No signs of power distress.

the total current (available) from the Duet won't change; if you have a usb current meter you might get a feel for the average current consumption of the Pi+Screen if you run them off a usb supply with a meter in line and that should give you an idea of the head room for other stuff.

DocTrucker

Thanks for the comments. I've taken a look at the schematics and the internal regulator drops VIN to 5V, 4A. The 5V is internally used to power the 3.3V drop down regulator.

@Danal you've pretty much got the setup I'm aiming for there.

this was the post i couldn't find before; tl;dr 3A overall limt

https://forum.duet3d.com/post/123336

(not sure if they're derating the regulator or that they assume 1A for internal use)

DocTrucker

@bearer thanks. Not a huge headroom by any sretch then.

dc42

@bearer said in Duet 3 Power Supplies:

this was the post i couldn't find before; tl;dr 3A overall limt

https://forum.duet3d.com/post/123336

(not sure if they're derating the regulator or that they assume 1A for internal use)

Small change to that: maximum total external 5V load is 3.0A, and maximum total external 3.3V current is 350mA.

@dc42 thanks for clarifying!