Dynomotion

Group: DynoMotion Message: 11084 From: karmannelectric Date: 2/14/2015
Subject: SnapAmp quadrature encoder inputs
What voltages can the SnapAmp quadrature inputs handle? My servo encoders
are powered from 5V and have differential outputs. Should this be a
problem? Also, do the differential inputs need to be terminated with a
120 Ohm resistor across them, like the SmoothStepper does? Finally, how
much +5V can I take from the SnapAmp on connector JP7? I'm not sure how
much my encoders require, so either way I'm most likely to provide my own
5V supply to the encoders.

Thanks,

Steven Ciciora
Group: DynoMotion Message: 11090 From: Tom Kerekes Date: 2/15/2015
Subject: Re: SnapAmp quadrature encoder inputs
Hi Steven,

There is no problem feeding in 5V differential signals directly int the SnapAmp differential inputs.  That is what they were designed for.

A 120 Ohm termination resistor across each + and - input (2 per encoder) would be a good idea if your encoders are capable of driving that load.  SnapAmp doesn't have any termination on board.

+5V passes straight through the boards and through the connectors so the main limitation is the ~1A limit of the connectors.  You should be able to draw at least 500ma for your encoders which would typically be more than enough for most encoders.

HTH
Regards
TK