1 Topic by Claghorn

  • Claghorn
  • Member
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  • From: Delray Beach, FL
  • Registered: 2012-10-22
  • Posts: 730

Topic: RAMBo mosfets?

I was poking around on http://reprap.org/wiki/Rambo and looking at the pictures, I wondered "where are the mosfets with the big heatsinks you'd need to run the 15A bed heater the specs say is possible?"

Finally found them looking closer at the pictures and they are cute little surface mount parts with a lot of copper PCB and holes around them, but no external heat sink.

Have mosfets really gotten efficient enough to switch that much current with that little heatsink? Impressive if true.

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2 Reply by elmoret (edited by elmoret 2013-11-17 15:35:47)

  • elmoret
  • Filastruder
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  • Registered: 2012-10-11
  • Posts: 6,048

Re: RAMBo mosfets?

The use PSMN7R0-60YS mosfets, which have an Rds of 4.96mohm. That's 1.11 watts @15A, not a big deal for a copper PCB to sink - especially with the boatload of vias they use around it.

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