Replacement for 741

My usual gumdrop is OPA197. Works from 4.5 to 36 volts and has great DC and AC performance.

Is that 3 volts rail-to-rail or +/- 3 volts? The 741 isn't a single-supply op-amp, the common-mode range doesn't include ground so it's not going to work with 3 volts on the + supply and ground on the -, it needs at least +/- 4.5 volts.

The LT1014 is a quad that's sort of like a much better-specced LM324, it's a drop in for that and can run down to 5 volts with a single supply and the common-mode includes ground, and from +/- 22 down to +/- 2.5 in dual supply so should be able to do anything an LM741 can do also. Unfortunately it's not that cheap.

I tend to think of "drop-in replacement" as meaning a device that has similar slew rate, GBW, supply voltage ratings, etc. such that you can just drop it in to an existing circuit or design with some guarantee it will work the same, as some circuits depend on those things being similar. one thing the LM741 has is a higher max supply voltage than you usually see these days on gum drops.

But then it sounds like he's talking about something else.

A true drop-in replacement has to tolerate +/- 22V power supplies, and would need similar offset-adjust pinout, which seems unlikely to be available.

The ten-lead flatpack (weldable) package of the original uA741 is definitely unavailable. Both the TO-8 and DIP-14 case styles are... pretty much unavailable in a modern device, DIP-8 (not the original uA741 package, but available in later years of production) is possible.

The TI 741 data sheet recommends min supplies +-10, so he's not literally looking for a drop-in replacement.

Low supply voltages benefit from using RRIO amps. They are common nowadays, so may as well.

I tend to run opamps from 5 to 24 volts, so something like OPA197 is handy.

For low power/low voltage my favorite quad is the OPA4322:

Last I checked AD doesn't have anything nearly as nice for the price. TI doesn't beat AD on price/performance all the time, but when they do they kinda smoke them silly

Nice, but 5v max.

I like singles. I can place them anywhere and don't agonize over unused sections.

t all the faults of the 741. Found a page that describes several replacemen ts, but I am looking for a chip that will operate at 3 volts or below. Or i s that asking too much ?

with a supply voltage of 1.8 - 6v ? Has anyone of you ever used this chip o r have another suggestion ? I like the low end of the voltage range but the high end could be higher.

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My apologies, I should not have used the phrase "Drop in Replacement". I am just looking for a comparator to detect a threshold, in school we were t aught to use 741(s), but that has been many years, and now comparators are available that output a digital signal. Searching I found the MAX931 w/Su pply of 2.5v - 11v and MCP6562 w/Supply of 1.8 - 5.5v. Both would probably work for a battery operated circuit. I am looking for something in a 8 pin package or smaller. [Dual or single] . Any help is appreciated. Thank you.

Which faults of the 741 do you have in mind?

If it has to operate at 3V or below then I'm not sure I understand why it has to be a drop in replacement for a 741. Can you clarify what you're trying to achieve?

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** I won't have it, the 741 has no faults, just a few limitations.

Like the DC3 aeroplane, the only true replacement is another one.

** Has some serious flaws. Eg; polartity reversal when inputs overdriven.

...... Phil

741s are nasty as comparators. The best comparator is a real comparator, and they are cheap. We use MCP6567, 1.8 to 5.5 volts, nice little open-drain dual part, but my gumdrop OPA197 opamp makes a nice comparator too.

I need to window-compare a mess of power supplies, and the MCP6567 is excellent for that. I'd use a little uP but programming is a nuisance.

Unlike parts that I could name, MCP6567 doesn't go ape if you poke a little current into its ESD diodes.

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hout all the faults of the 741. Found a page that describes several replace ments, but I am looking for a chip that will operate at 3 volts or below. O r is that asking too much ?

ks with a supply voltage of 1.8 - 6v ? Has anyone of you ever used this chi p or have another suggestion ? I like the low end of the voltage range but the high end could be higher.

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am just looking for a comparator to detect a threshold, in school we were taught to use 741(s), but that has been many years, and now comparators are available that output a digital signal. Searching I found the MAX931 w/Sup ply of 2.5v - 11v and MCP6562 w/Supply of 1.8 - 5.5v.

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I looked at the specs of the 'MCP656X', but none of the members of that fam ily are available in DIP package. From the MCP website, the 'MCP654X' is available in a PDIP package. Would that make a good substitution ? Thank You.

Those parts look very similar, but less power and slower than the '656 parts. Should be OK. Get some and try!

I haven't used a DIP part in years! Lots of years.

--

John Larkin      Highland Technology, Inc 

The best designs are necessarily accidental.

Why use a slow op-amp with internally compensated for unity gain stability as a comparator ? IIRC, in those days, the 748 (741 without internal compensation capacitor) was recommended as comparator.

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** The 748 was an all round better part than its relative. Much greater GBW and slew rate.

Second cousin to the LM301A, which was my pick at that time. Years before special low noise types like the NE5534 appeared and wiped the board in 1976. Still top of the list for line level audio, along with the dual version, NE5532.

..... Phil

====

he board in 1976.

NE5532.

Still searching I found the following comparators on Newark.com. Both are manufactured by TEXAS INSTRUMENTS and inexpensive. I tried to find the definitions for difference between 'Differential' vs 'P recision', but all I found was that all comparators are 'Differential'

LM393P Comparator Type: Differential No. of Comparators: 2 Comparators Response Time: 300ns Supply Voltage Range: 2V to 36V Comparator Case Style: DIP No. of Pins: 8 Pins

LM393N/NOPB Comparator Type: Precision No. of Comparators: 2 Comparators

Comparator Case Style: DIP No. of Pins: 8 Pins

Both pages show a link to an upgraded version: LM393B (specs below) ========================= ===========

LM393B Number of channels (#) 2 Output type Open-collector

Vs (Max) (V) 36 Vs (Min) (V) 2 Vos (offset voltage @ 25 C) (Max) (mV) 2 Iq per channel (Typ) (mA) 0.2 Input bias current (+/-) (Max) (nA) 25 Rail-to-rail No Operating temperature range (C) -40 to 85 Features Standard comparator VICR (Max) (V) 34 VICR (Min) (V) 0

I like both singles and duals, can't remember when I last used a quad though. Agonizing with the unused half can be light or bad, depending on which opamp it is....

Dimiter

------------------------------------------------------ Dimiter Popoff, TGI

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If you need a comparator just 741 fast and 15V max V- to V+ is OK just go for the LMC6482 as I would :-). Has been a workhorse for us for many years, still available, not sure about DIP but SO8 most certainly. Brings some advantages compared to the 741 - RRIO, fA range input current. And some more noise which in a comparator application would go unnoticed.

Dimiter

------------------------------------------------------ Dimiter Popoff, TGI

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The original PNP-front-end family (LM324, 393, 2901, those guys) did horrible things to all sections if one pin was pulled slightly below ground. The opamps had horrible channel crosstalk of any railed, so were useless as dual or more comparators.

Maybe the B versions are fixed. The TI data sheets suggest not. As usual, the hazard is hidden in a tiny footnote, whan it should be in bold type six places.