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36v4 at 48V

Is anyone having troubles getting the Pololu 36v4 driver to run reliably at 48v? I am powering the 36v4 off a 48v linear power supply. With the default DRIVE settings (2649), I can only get a NEMA 17 to turn maybe about half a revolution before either the A or B predriver fault becomes active. If I set the DRIVE settings to 175 (the most permissive), I can get the same motor to run OK at 1.5 amps, but it keeps asserting predriver faults at anything above 1.5A.

Unfortunately I need the very high voltage because the ballscrews on my CNC are somewhat fine pitch and I’m trying to achieve a reasonable feedrate. The DRV8711 chip is supposedly rated to 50V, and it looks like the rest of the components on the 36v4 is rated above that. Any hints on getting this to work reliably?

Hello.

Can you check the silkscreen on the bottom side of the board to see if it is labeled “md38a” or “md38b”? That label is just below the motor outputs.

- Patrick

Ok I somehow didn’t notice that I have a mix of md38a and md38b boards. The B boards I assume have the gate resistors, because they seem to be having no problem even at 2.5 amps. Is there any way I can trade in the md38a boards I have?