Can anyone recommend a low quiescent power, low cost, CMOS op amp suitable for use from a single supply, that can really pump out current when required (50 - 100 mA)? GBW and slew rate requirements are modest and most anything above 1 MHz and 1 volt/us would do.
If it's available in a through hole package that is a plus, but not required.
50mA is out of "noraml" opamp range. So power opamps, Are any of those single supply? Some audio car thing maybe?
George H.
Ohh, or do your own opamp-transistor power booster.
100mA could be done class A. (depending on the voltage.)Geo
AD8565?
Why does an opamp care if it's single or double supply? None, that I know of anyway, *have* a ground connection.
I've used video opamps (like the LM7171) for audio line drivers (Howland current pump) that will drive the current but they aren't CMOS and the Iq is going to be a lot more than I think he wants. There are a lot of specs left out, here.
I guess I assume a single supply opamp can have it's input (and maybe output) work right down to near the negative rail.
George H.
Looking at the LM7171, it does come in a PDIP package and has an Iq of
8.5mA, so not too bad. There is also an LMH6672 that comes in a SO8 with a power pad (handy at these currents). It's slower (slew rate only 170V/us ;-) but the Io is 200mA.
That's an odd definition. I use "normal" opamps all the time with only a positive rail.
Huh? You leave the negative rail floating? (the LT1013 is "my" single supply opamp.)
George H.
Interesting that TI makes the same part number for a fraction of the LTC price. Kinda noisy.
No, I tie it to ground. With most bipolar opamps you can't get the output to ground but that need is a rarity (and CMOS R-R opamps work for almost all of those applications). If you really need to get to ground, perhaps as someone else pointed out, perhaps a class-A output stage (an NPN voltage follower) might be in order.
I don't use any LT parts. Too expensive. My go-to opamp is the Microchip MCP629x. Dirt cheap and rather good. I use tons of the quads and the SOT-23 singles are quite useful too.
6 volts max. That's the problem with cheap RR opamps; they usually have low supply voltages.
I use a lot of LM7301s... 43,000 so far. SOT23, decent amp, RRIO, 30 volts.
LTC has a few high-performance opamps that are worth the price. LT1028, LT1124.
LM8261 is cool: RRIO, 30 volts, 21 MHz, stable with any capacitive load.
I generally have to live within 5V (even that can be a problem) so they work great. There is also a MCP6H9x part with 12V rails, though higher noise and a few cents more expensive.
sounds as if it's pretty much what you want. I was impressed by it's high output current when I first came across it.
Farnell stock it in volume
but only in the SOIC package - it looks as if ON-Semiconductor has stopped making the DIP-packaged version.
It may be odd now that we have rail-rail op-amps, but it was fairly common terminology in data books from before my time up to at least a decade ago, if not to the present.
I think the LT version is a few dimes more. (In low volume.) There are some higher grade ones with lower offset voltage. (and an extended temperature range.) I like that it does 44 V on the supply. (I've run some from 48V with no problem... but not for sale, just testing/ prototype etc.)
George H.
That's the definition of single supply op amp - or at least the definition I know. Rail-to-rail op amps have a double input stage and switch from one to the other as the inputs get close to one rail or the other. Jim Thompson could probably tell us about it.
The outputs tend not to do as well close to the rail as the inputs do.
It's odd terminology even given RRIO opamps. I've used opamps that I couldn't get within 2V of a rail, with a single supply.
Looks OK!
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