Advised Current Limits for Duet 0.6

  • Hi.

    What are the designed limits for the low side switched devices? I've had a look at the wiring diagram and the limits are clearly not determined by the mosfet selection, it is more likely that this is determined by the connectors?

    Heated bed: 10A
    Hot end heater? Two of the 2.54mm pins so 4-6A?
    Fan0? only one of the 2.54 pitch pins so 2-3A?
    External PSU enable? Mosfet can sink 1.05A. Limit to 500mA? This pin grounded by the Duet means PSU on doesn't it?

    As said elsewhere I'm looking at appropriate fusing, especially for anything with long wire runs. I was thinking of leaving the PSU current limit the V_in, but perhaps a fuse there also would be wise. I'm not planning on fusing the steppers as they are driven by a current limiting driver. If there is an over current I'm going to assume this means a board failure and so a fuse on the V_in or 5V supply would be the best place to catch this?

    With regards to the 5V supply I was considering fusing the supply at 2A, is that plenty so long as additional devices like a screen don't pull power from the duet?

    My set up is fairly standard with IR probe, 5 steppers (4 1.33A from Ormerod - 2 z-axis running in series - and 1 small drive from E3D for the titan), Standard E3D V6 24V heater, 300W 24Vsilicone mat heater, upto 3 end stop switches and a filament detector. Power supply is a 350W 24V PSU from Ooznest and I will source an appropriate 5V PSU to supply the duet and ancillaries.


  • administrators

    The Molex KK connectors are best limited to 2A per pin, so I'd say 4A max for the hot end heater and 2A max per fan (but most fans used in 3D printers draw much less than this).

    The Duet 0.6 can supply more than 10A bed heater current if you bypass a weak PCB trace with a wire. I'm not certain of the rating of the bed heater terminal block on the 0.6, but it might be 16A.

  • Thanks!

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