Dual 741 / 747 modern upgrade

[ancuk]

Can anyone suggest a surface mount, newer, better, faster replacement for my old UA747 designs? I really need the offset null pins, but in a dual package. Board space inhibits me from using single (741-type) chips. Thanks!

[audioguru]

An 8-pin package doesn't have enough pins for offset-nulling. Add your own offset-adjustment circuit to any dual opamp. Or buy a modern dual opamp that has laser-trimming for an extremely low offset voltage. Sorry, I don't know their numbers.

[ancuk]

Thanks for the quick reply! I know that an 8-pin design won't accommodate null ofset pins - I don't mind if it has 14,16 etc, so long as the package is smaller than my current UA747 design! I fear that adding external compensation circuitry will increase board usage. My design is used in a DAC analogue output board that has varying cable lengths attached to the output - hence the need for offset adjustment. I tried an 'auto-adjusting' circuit on earlier test boards, but wasn't happy with the results. Now back to square-one, and look desparingly at using 747s again, or a couple of SMT 741 upgrades like the AD711 - unless anyone can suggest different  !!  :-[

[MP]

The purpose of offset null is to compensate inconsistencies inside the op-amp that do not allow it to zero out when it should. It is not intended for the regulation of varying output loads. This is done through impedance and/or amplification methods. Perhaps I did not fully understand your post, but it does not sound like you are using the offset null correctly.

MP