Servo driver heatsink?

Hi all,

Just wonder if servo driver IC on the new duet board need heat sink ? servo current pre-set in firmware or in config file ?

You mean the stepper motor drivers? If they are the A4988 as used on previous RepRaps, then at the 800mA current programmed into them in config.g they should not need a heatsink.

@Tru168: The Duet uses A4982 stepper driver chip (not servo), the same that is used on the Melzi boards. The A4982 is a bigger package than the A4988 (used in the Pololu/stepstick boards, often used in RAMPS and Sanguinololu electronics). Both have a heatsink on the bottom of the chip, which is soldered to the board, so uses the ground plane of the board to disperse heat. The Melzi and the Duet both have large ground plains, so are very effective at keeping the chips cool, and should be able to run motors at 1.3A easily. The extra heatinking on top of the chip is only marginally effective; the chips don't have any particular heatsink part on-die itself on the top of the chip. It helps the Pololu/stepstick boards, because cooling is otherwise very limited by the small size of the ground plain on those PCBs.

And yes, stepper driver reference voltage is set in the config; there are no potentiometers on the board to adjust.

Ian
RepRapPro tech support

Edited 1 time(s). Last edit at 12/25/2013 04:46PM by droftarts.

Hi guys, Thanks for the answer. Yes , I mean stepper motor. been built several CNC but still have typo sometimes , especially I'm repairing / building RC models recently and always mentioned "servo" in aero-modelling. Downloaded A4982 data sheet, technical data seems similar with A4988 but double in physical size.