Have you considered SSR for driver or directly to load?
Up to 100 amp and 1K hz

http://www.crydom.com/en/Products/C...nd 48 to 300VDC - AC or DC control&SBCatPage=

 

I would suggest to use the popular NE555 as the mosfet driver.
Just set the timer chip as a 'schmitt trigger', with diode-clamped input.

 

Assuming the output is open-collector npn, an inverting mosfet driver might be needed.
With little soldering required, this is simplest circuit that I could think of:
Just make sure the IC is close with the mosfet.

 

Re the 555 circuit above; the output pin 3 is a push-pull driver and can drive the FET gate by itself.

The discharge pin 7 is an open-collector pull down driver and is the same phase as pin 3, but it is considered bad manners to connect them together. There's just no need, you can leave pin 7 disconnected. Especially in the interest of "little soldering required".

 

Re the 555 circuit above; the output pin 3 is a push-pull driver and can drive the FET gate by itself.

The discharge pin 7 is an open-collector pull down driver and is the same phase as pin 3, but it is considered bad manners to connect them together. There's just no need, you can leave pin 7 disconnected. Especially in the interest of "little soldering required".

Maybe I was thinking too much about fast turn-off fall-time, and somehow forget about the rise-time.

 

Peak current from the 555 output in the posted circuit is way above the rated 225mA Absolute Maximum (albeit briefly). A gate resistor of 68 Ohms would obviate that and also provide suppression of any gate ringing.

 

Peak current from the 555 output in the posted circuit is way above the rated 225mA Absolute Maximum (albeit briefly).

I've seen a lot of speculation about this issue. The usual 200mA sink/source rating for continuous current is simple enough, but I have not found definitive answers about transients. Different 555s may have different internal protections. Some argue that internal resistance alone is enough to prevent damage to the 555 even during a brief short, or driving a capacitive load like a MOSFET gate. (Key word is brief.)

I bet the OP could get away with the schematic posted without adding a gate resistor. It may not be good form.

 

I bet the OP could get away with the schematic posted without adding a gate resistor

Maybe, but if this is for industrial use I wouldn't want to risk it. Here's what the TI datasheet says:

Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device.

 

So if I used this, http://www.ti.com/lit/ds/slfs022h/slfs022h.pdf, and since its not for industrial use, no resistor would be required, and using this proximity switch, http://datasheet.octopart.com/XS230BLNAL2-Schneider-Electric-datasheet-12864813.pdf
It should work?

 

Actually I have successfully used Omron SSR's but the expense is just way too high. This is a 10th of the cost..or less actually..even getting the Chinese junk..

 

Is this a proprietary project?

Am I the only one that's curious?

 

So if I used this, http://www.ti.com/lit/ds/slfs022h/slfs022h.pdf, and since its not for industrial use, no resistor would be required, and using this proximity switch, http://datasheet.octopart.com/XS230BLNAL2-Schneider-Electric-datasheet-12864813.pdf
It should work?

I believe it should, unless Murphy's Law get to you.
Take advice from other members too.

 

Now I'm wondering, why not just use a dedicated driver?

 

no resistor would be required

Don't you want to suppress any gate ringing tendency (which can lead to overheating of the FET)? Surely a few cents/pence/whatever for a resistor won't break the bank?

 

Alec t,
You are correct a resistor certainly wont break the bank, Wondering where to put it if I did..
Tho I certainly dont pretend to be an electronics guy, (know enough to be dangerous),
AfdhalAtiffTan,
I also thought a dedicated driver might be easier, but what do I know?
overall, I really am just looking for a easy and fairly robust solution...

 

Wondering where to put it if I did..

If using AfdhalAtiffTan's suggestion it would go between the 555's ouput pin 3 and the FET gate pin (physically close to the gate pin).

 

I'm sorry to have introduced any confusion about using that gate resistor - I'm all for it since it's essentially free insurance. I was speaking somewhat philosophically when I speculated the OP could get away without it. Many DIYers around here likely get by without it as well. That doesn't mean it's good form to omit it, or that you shouldn't use it. If it was costly to include, we'd have a different discussion.

 

No worries for me,
What about AfdhalAtiffTan's second guessing himself on whether a dedicated driver might be better, anyone's thoughts on that?

 

I ended up learning a lot after my post, I have to thank THE_RB, Alec_t, and wayneh for their helpful posts.

This is what I come out with:

I added a decoupling cap (C2) to suppress any further ringing.

I believe a dedicated driver is better as the rise and fall time are much shorter. 555 rated somewhere in 1uS while a driver might gets better than 200nS.

Other than the price, I can't think of any other reason for why not.

 

AfdhalAtiffTan
so if i used the driver I mentioned earlier, would this schematic you show work with no changes? would I have to invert the output from the Proximity switch?