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RRIO OpAmp Recommendation?

I need a rail-to-rail I/O OpAmp, 5V Vcc is fine, slow speed setting a current mirror.

What would you guys in the discrete world recommend as being well-behaved, no peculiarities, etc? (And readily available ;-)

Thanks! ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

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| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Reply to
Jim Thompson
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I'm a fan of the AD8605. It has fast local feedback wrapped round the output stage, so that its output impedance doesn't climb nearly as fast as most RROs.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Thanks, Phil! That's how I design them on-chip... local feedback cures that transconductance nastiness. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

I use a lot of LM7301s, but they are 32 volt parts and cost more than lower voltage stuff.

LMV931 is OK.

AD8565 isn't cheap, but it's a remarkable part. 16 volts RRIO, 250 mA peak out, comes off the rails clean in a microsecond, c-load stable.

--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

TLV237x

Tim

-- Seven Transistor Labs Electrical Engineering Consultation Website:

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"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...

Reply to
Tim Williams

Thanks for all the tips.

I sent the client (in Taiwan) a solution using the AD8605 that Phil suggested (and I could find a model for).

I'll provide him also with all the alternates... this is a slow loop so I think any will do.

Thanks again. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

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| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Reply to
Jim Thompson

What specs?

I've been using the MicroChip MCP6294, mainly because they're cheap but the specs matter.

Reply to
krw

That looks OK for non-critical stuff. The single MCP6291 in SOT23 is around 40 cents in quantity. (I like singles, usually.) Somewhere there ought to be a really cheap workhorse opamp, ten cents maybe.

--

John Larkin         Highland Technology, Inc 

jlarkin att highlandtechnology dott com 
http://www.highlandtechnology.com
Reply to
John Larkin

Already exists. LM358, $0.09 in quantity 1 from Newark. And it's a dual! ;)

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16013415

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

But not RRIO. ...Jim Thompson

--
| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    | 
| San Tan Valley, AZ 85142     Skype: skypeanalog  |             | 
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  | 
| E-mail Icon at http://www.analog-innovations.com |    1962     | 
              
I love to cook with wine.     Sometimes I even put it in the food.
Reply to
Jim Thompson

I'm paying less than that for the quad. Less than half for the single (though I haven't used any). Yeah, it's a general purpose opamp with nothing special going for it except its cost. It is R-R I/O, which command a premium over others. I can get non R-R opamps from NJR for well under $.10 but they're pretty old-school bipolars. I'm trying to keep my analog rail under 5V, which kinda dictates R-R.

Reply to
krw

Picky, picky.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

Speaking of, I've been looking for "single supply" (includes ground) or RRIO chips with higher supply voltage (12V minimum, >16 preferred for reliability). Catch is: needs more GBW than an LM358.

Closest I've seen is CA3130, but it seems rather obscure (almost everything CA- is utterly obsolete, though Intersil still seems to be supporting a few).

There was one or two from TI or LT that meet or exceed (particularly in offset), but they're no cheaper.

Decomp or current feedback would be fine (it's for gain ~ 50, GBW >=

25MHz), but both are like hens' teeth, or have way too much GBW (video amps, etc.).

Tim

--
Seven Transistor Labs 
Electrical Engineering Consultation 
Website: http://seventransistorlabs.com
Reply to
Tim Williams

I remember those. The CA3140 was more or less the same part, but with a bipolar totem-pole output stage.

The CA3100 was magic back in about 1980--it was the only amp we could find that could handle multiple channel PSK data in a 3-MHz bandwidth with acceptable intermod.

TI makes a bunch of quite reasonable higher-voltage op amps, e.g. the OPA188/2188/4188 chopamps.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

But the LM358 doesn't use any bias, and so there is crossover distortion at the mid point if used in a linear application such as audio. Maybe that's not an issue for other applications?

-Bill

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Reply to
Bill Bowden

For nine cents in onesies, he expects perfection. An arrant varlet, forsooth. ;)

LM358s and 324s are occasionally useful, but usually in unipolar applications, true. A figure of merit for a given design is how crappy an amplifier you can use and have it still work well.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

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