Comparitor Use Question?

Question

How would i use this comparator: http://www.analog.com/en/amplifiers-and-comparators/comparators/AD8611/products/product.html

to do the following:

A reference voltage, Vref, is 0.1V. If the voltage of the input is below Vref it sets the output to 0V, but if the voltage is above Vref the output voltage is bumped up to 5V?

Answer 1

Go to any distributor for their selection tools. Any general purpose 5V or more with Rail or Rail or TTL outputs should work. I like Digikey, Mouser, Newark, Allied Electronics.

How about this one for small:

http://www.national.com/ds/LM/LMC7211.pd...

Answer 2

Do you really need the 4 ns switching speeds? If not, use a LM339, much more reliable, and the output will be much closer to 0 and +5v

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Answer 3

Put your 0.1V reference on the +input pin.  

Put your signal on the -input pin.

Take the output off of the QA output pin.  

If you want it to latch, put the latch signal on the latch input pin.

The output will not be 0 and 5 V, it will be more like 0.2 and 3.5V (TTL levels).

If you really need zero and five volts, then you'll have to add some amplification and level shifting on the output.

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