Hi all,
Does anyone know of any micro-power Comparators/Op-amp (dual) which allow the use of 2 pairs of rails i.e 9V & 4.5V along with 4.5V and
0V. I'm struggling with board space and wondered if a part exists.Cheers,
Osman.
Jamie,
Jamie,
I've had to add some extra circuitry in for protection purposes, and realized at the last minute! Thanks for the advice.
Osman
Your board must be small, considering the available packages out there.
If you have to, 2 compactors back to back on a small board that can be edged soldered in the main board.
Jamie
Why two sets of rails? Do the outputs need to be referenced to 4.5V and 0V? If so, it might be easier to run the comparator from 9V-0V, and level shift one of the outputs. OTOH, there may be duals with both emitter and collector (source/drain) brought out, ala '339.
How about two, in small packages (e.g. SC-70)?
.
Krw,
The outputs do need to be referenced to 4.5V and 0V. Are you saying use the SC-70 as a level shifter? I'll check the '339 as well.
Cheers,
Osman
The SC-70 is a package, in which various parts might come. It's not a designation for a part.
Do a search in Digi-Key for comparators in the SC-70 package, see what you come up with.
-- www.wescottdesign.com
No, there should be comparators in an SC-70, or similar. Use two, they're small.
As I mentioned, the other alternative is a dual comparator and then level shift the output of one to the 4.5V reference. Depending on what this is driving, it may be as simple as a couple of resistors or maybe a FET and a resistor. I'd have to know more.
Like, you want to have output ranges 4.5V...9V on one unit and 0V... 4.5V on the other? You could (it has low gain) program an LM13700 for 10 uA, and diode-clamp its output pins at 4.5V; this part has built-in Darlington follower transistors that can buffer the clipped output, so you wouldn't be stuck with microamp drive, more like a milliamp.
The clamp diodes, though, you'd have to supply, and pulldown resistors for the followers.
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