Please suggest me a selection of operational amplifiers for DC experimentation - Page 1
Forum section: electronics / general

author: DC1MC
author_rank: Super Contributor
timestamp: February 01, 2019, 07:22:22 pm
content: Dear metrology masters, as my plans are slowly progressing but the information I've found about the best OP for buck are sometimes contradictory I kindly ask you to suggest me a selection of the "best bang for the buck" OP with or without AZ to use them for DC precision experiments (controlled U/I source, etc.).I want to place an order with Arrow, that tries to compete with the established giants like Digikey and offers for a short time an 120USD cupon (SAVEBIG) and free overnight shipping, no matter the order value. I did test the shipping with a small order, it was spread over two warehouses in US and one in Belgium and it still managed to reach Germany in two days, that is by itself a small wonder.Please try to argument your OP choice in a short sentence, like "Low price, low drift" or "High Supply voltage and output swing" and so on. Of course, personal experience is what I'm searching for, marketing it's showing itshead in the datasheets lately and had enough of these*after almost each parameter.Thanks and cheers,DC1MC

author: awallin
author_rank: Frequent Contributor
timestamp: February 01, 2019, 09:05:32 pm
content: did you read this thread?https://www.eevblog.com/forum/metrology/low-frequency-noise-of-zero-drift-amplifiers/

author: DC1MC
author_rank: Super Contributor
timestamp: February 01, 2019, 09:15:04 pm
content: Quote from: awallin on February 01, 2019, 09:05:32 pmActually yes, @chuckb is 'da man, but I would like to get a wider set of opinions and applications, in any case Chuck's list it's the base plan if nothing new/better comes in this thread during the WE.Cheers and thanks,DC1MC

author: TiN
author_rank: Super Contributor
timestamp: February 01, 2019, 10:18:56 pm
content: QuoteWrong approach. Define purpose of opamp in your circuit and work suitable opamp for THAT purpose.Example? You design low noise amp for low impedance source? Okay, LT1028 at 5$ prolly nice choice, but ADA4522 for 1$ not so good. Designing 10V amplifier for reference gain block? Well, LT1028 for 5$ would be rather useless for this. So which opamp is better for buck?

author: DC1MC
author_rank: Super Contributor
timestamp: February 01, 2019, 10:35:01 pm
content: Quote from: TiN on February 01, 2019, 10:18:56 pmWell, obviously one that fits the purpose and it's the most cost effective for a hobbyist (companies may have other criteria, like long/short term availability, facile automate placing placing and small package, and so on).Something like: for X purpose, from the data sheet pov A, B and C are identically suitable, but A it's in a 3x3mm package MSOP8, I've tested B and it's drifty and C it's in a DIP8/TO99 and reasonable cheap, but it may not be available in 1000s.Cheers,DC1MC

author: TiN
author_rank: Super Contributor
timestamp: February 01, 2019, 11:02:45 pm
content: Without having A B C D E specification requirements you are asking for people to guess and do parametric search for every opamp.Sorry, I see this listing rather pointless waste of everyone's time.If you want something like summary too see what exists, just get yourself AoE and read thru opamps section. Instead of just only listing datasheet parameters, they actually went thru trouble to test some interesting aspects of various purpose opamps.In the end if opamp cost 1$ or 10$ does not really matter even for cost effective hobbyist, as it's few pieces project, not a production design that need account for price in 1000's of units. Your time spent on designing circuit cost much more than opamp itself.

author: MasterT
author_rank: Frequent Contributor
timestamp: February 01, 2019, 11:03:51 pm
content: Visit microchip web-site, there are many options for OPA selection.Arguments :1. Many parts still available in DIP packages. Worst case scenario SOIC. Hobbyist friendly.2. Low offset (500 uV) MCP6021/2/3/4, low noise.3. Price usually 2 times less than similar parts from analog or TI. LT is from different planet on the price policy.4. AZ, PGA, instrumental etc, have bought a few myself to have around.My thoughts about AZ - don't accent on this species, IMHO, it's was developed in 80-90-th, in "no microCPU" time, and may still be applied in pure analog no-CPU circuits, but it's quite rare nowadays. Better to do same trick zeroing offset for complete DC path with a switches and ADC, calibrating all bunch of DC uncertainties in one loop.Declaimer: I'm not affiliated in any way with a Microchip company.

author: David Hess
author_rank: Super Contributor
timestamp: February 01, 2019, 11:46:42 pm
content: I'm going to ignore zero drift parts.Most economical precision operational amplifiers due to multiple sources:OP-07 - Single, bipolar, dual supply, 44 volt - $0.75.LT1013 - Dual, bipolar, single supply, 44 volt - $1.91 - Improved replacement for the 358 - LT1006 is the much more expensive single - LT1014 is the quad but costs more than two LT1013s.Lowest input bias current precision operational amplifiers:LT1008 - Single, bipolar dual supply, 40 volt, externally compensated - $5.65 - Improved replacement for the 308.LT1012 - Single, bipolar dual supply, 40 volt, external overcompensation - $3.29 - Buy this because ...LT1097 - Single, bipolar dual supply, 40 volt, external overcompensation - $3.59 - Low cost version of LT1012 which costs more!The single LT6010, dual LT6011, and quad LT6012 are newer less expensive replacements for the above but I have not used them.Low noise precision operational amplifiers start with the OP-27/LT1007 series however I am not aware of any specific low cost versions of these to recommend. The LT1012 above is an exception to this rule because it is almost unique and there are lots of OP-27/LT1007 equivalents.Quote from: DC1MC on February 01, 2019, 10:35:01 pmYou have to be a little careful about packaging. The best precision parts have dies which are too large to fit in the smallest packages. This is why the LT1013 in the SO-8 package has a nonstandard pinout; the die had to be rotated 90 degrees. Later parts like the LT6010/LT6011/LT6012 mentioned above were redesigned to fix this but the highest performance parts will not be found in the smallest packages.

author: razvan784
author_rank: Regular Contributor
timestamp: February 02, 2019, 02:14:23 pm
content: Here is my short list. I've excluded 5V parts, high voltage only.Precision non-chopped:OPA277P (without the A suffix) - probably the lowest offset TC you can find without resorting to choppers - 0.15uV/K max; also quite low noise, but not very low input currentOPA140 - JFET input, but with DC specs typical of bipolar precision parts; also very low noise. The ADA4625 is a little better but more expensiveAD706 - bipolar input, but with ~100pA bias currentLT1013 - very low input current noise for a bipolar opamp, low offset current TC around room temperature; supposedly perfect for LTZ1000 references; highish Avol; other parameters less than spectacularChoppers:OPA189 - low noise chopper, for source impedances up to a few kohmsLTC2057 - lowish noise chopper, for source impedances from a few k to 10kLTC1150 - chopper for source impedances up to 100k

author: Echo88
author_rank: Frequent Contributor
timestamp: February 02, 2019, 04:27:41 pm
content: If youre really serious about designing electronics (particularly accurate stuff) i strongly suggest gettinghttps://www.amazon.de/Art-Electronics-Paul-Horowitz/dp/0521809266/ref=sr_1_1?ie=UTF8&qid=1549124075&sr=8-1&keywords=art+of+electronicsIts costly, but its THE reference when it comes to good circuit design and contains a chapter detailing all OP-basics and most of the advanced stuff, which needs to be understood to build your intended circuits. It will aid you in understanding which OP to pick for which application while avoiding most pitfalls.It also contains the comparison-lists you look for: sorted by jellybean-parts/input architecture/AZ...A few OP-Amps can be found in this list, which i made as i intended to build a KVD-buffer:https://www.eevblog.com/forum/projects/very-low-bias-current-op-amp-to-buffer-a-kelvin-varley-divider/msg1302325/#msg1302325but the list misses for example very good OPA-parts.

author: Kleinstein
author_rank: Super Contributor
timestamp: February 02, 2019, 05:29:13 pm
content: The best OP for a circuit really depends on application.A good one not yet mentioned before is the ADA4077.Instead of OP27 / LT1007 the ADA4075 or AD8675 more modern alternatives, if it needs to be fast and accurate.There are plenty of 5 V supply AZ OPs that may be interesting if 5 V are enough.

author: not1xor1
author_rank: Frequent Contributor
timestamp: February 04, 2019, 09:04:06 am
content: Quote from: Kleinstein on February 02, 2019, 05:29:13 pmA few days ago I ordered a 4.5-55V supply opamp just to test a 50V PSU circuit (not floating), without immediately realizing that its specs are fairly good, likely better than that of ADA4077:https://www.analog.com/media/en/technical-documentation/data-sheets/ada4522-1_4522-2_4522-4.pdf55 V, EMI Enhanced, Zero Drift, Ultralow Noise, Rail-to-Rail Output Operational Amplifiersmax offset 5µV, max drift 15nV/K, 5.8nV/√Hz noise, 117nV p-p from 0.1Hz to 10HzI just wonder why they do not consider it a precision opamp... might that depend on long term drift?

author: tszaboo
author_rank: Super Contributor
timestamp: February 04, 2019, 09:33:54 am
content: OPA2227, OPA350, LTC2057HV is something I use sometimesINA141 is also nice.