Mosfet Drivers and Input Hysteresis

It's customary to provide your own hysteresis ;-)

Seriously, a couple of resistors do the trick. Or drive the driver with with Schmitt.

Yeah...but I'm trying to reduce the component count.. I make my own PCB's so if my circuits are low in components then I don't have to do much PCB drafting and fab.. D from BC

Or just spring for a Schmitt trigger input buffer (or build one).

Robert

It might end up doing that if I have a favorite mosfet driver and I don't like it's input hysteresis :( I know many ways to create hysteretic circuits...I just don't want to include one.. :) D from BC

But then you'll be stuck with expensive boutique parts that hardly anybody else uses.

Make it work first. This is the wrong place to introduce a high impedance node.

RL

The mosfet driver IC input will get a slow non square signal but it'll be from a relatively low impedance source. The input shouldn't flap around in the wind so to speak.. But I'll check to see if anything else will kick the mosfet driver input. D from BC

Ahh.. but if the boutique parts speed up my project time..great! As long as the boutique parts stay at a insignificant cost level.. Ex..I change $900.00 for a one off project.. One $4.00 boutique part is insignificant.. D from BC

Turn the source into a comparator with hysterisis. This is the wrong place in the circuit to decide whether or not you want to switch. The decision should already have been made.

Even under those conditions, you'll see drivers with hysterisis equal to 30% of the input logic supply rail - and for good reasons.

RL

Ok then. As long as they don't have to build another one in three years and then your part has gone unobtanium.

Yeah..that's the risk... It could be good for business.. :P I just say "It's not my fault Supertex discontinued the part." I can make a new design with another part.. but that'll be another $900.00 :) Isn't that just evil :)

I do recall on one design where I couldn't find a boutique part, did it the long way, did the pcb and then found a boutique part.. Damn.. So.I kept the original PCB artwork and merged in the artwork for the boutique part.. So...if the boutique part got discontinued..the artwork exists for the fatter equivalent circuit. Then I turned the situation into a selling point.."Discontinued part resistant design". :) D from BC

Problem is, some day word gets around. Clients don't like that ;-)

That's what my clients expect (and get) with every design...

Another thing is that driver pushes 14 amps! Better watch that bypassing...

An easy one would be a low-voltage '555. Hysteresis from

It's a favorite technique..but it's still an extra part that I think I can avoid it if I chose the right mosfet driver having about 1V of input hysteresis. I've haven't received an email from IXYS yet..

I want a new 555 :) I want 2 high speed internal comparators (nS) rail to rail with no ties to internal resistors. Something like what Analog devices has... And.. I want 1 fast internal RS latch. Maybe 5V HC type. And...Bonus if I can get a 1A push pull drive output up to 16V. Call it the Super555 :) D from BC