Quote
bobc
#19 change E-STOP buffers to HCT type to always drive FETs at 5V and remove inverting drivers on heater outputs;
If you want to drive the FETs with more than 5V, there are a few "outside the box" options that come to mind. Besides the readily available FET drivers designed for this (which are a bit pricy), it seems that using an op-amp or comparator might work well. You can set the threashold voltage (even make it adjustable based on the I/O rail, if desired), you get inverting or non-inverting drive with the same part, and you could probably even fold E-STOP logic into the threashold level (pull the threashold level to above the logic supply rail, so the comparator is in an known state regardless of the signal input). The venerable LM339 seems like it might work well if you don't need really fast turn-on times (and they're dirt cheap). This would also remove the need for the additional 5V power rail.