I'm looking for a good comparator to work as a gate drive for a power MOSFET. I used an LMV321 in my simulations, but I just found out the lead time for these devices is about 2 months. I'm looking at rail-to-rail voltage of 0 to 5V and I need something with high gain so I can switch the MOSFET quickly. The comparator should also be available in a DIP package. I can always try a u741, but I'd like to know what else is out there.
Thanks in advance.
The LMV321 is an opamp and wimpy both as a comparitor or for driving a FET gate. Better would be a LM393 type comparitor with something like a 180ohm load resistor. Basically, it's available everywhere, 8 pin dil, cheaper, more precise, much faster and even has better rail to rail voltages. john
For heaven's sakes, use a real comparator! It shouldn't be hard to google for a suitable one, but remember, typically a comparator has an open-collector (or open-drain) output, so you need to pull up its output. This could be a factor if you need fast switching - you have to size the pullup resistor to give you a fast enough rise time to your load, while not blowing out the output device.
I don't know any numbers off the top of my head, but you might try
There are other ways of getting a fast rise time, of course, like some kind of totem-pole, or a really fast opamp, or ...
Good Luck! Rich
i've always liked the LM081/2/4 etc...
-- Real Programmers Do things like this. http://webpages.charter.net/jamie_5
Best thing for the job might be an LM311 comparator. It's readily available and costs almost nothing, but it has an open-collector output and is active-low, though, so you'll need a pullup resistor capable of driving your MOSFET.
Winfield
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