a question about LM224

Oliver Ou

Other Parts Discussed in Thread: LM224

Hi ,

Our customer compared the datasheets of LM224 between TI and ST, and found a strange behavior about the CMRR as below picture.

Can you help check and give some comments why we have so large different?

Thanks a lot.

Oliver Ou

over 9 years ago

0 Clemens Ladisch over 9 years ago

Guru 318050 points

ST's schematic diagram is identical with TI's function block diagram, so in theory, there should be not much of a difference.
(And both datasheets specify the same guaranteed value.)

ST's CMRR does not degrade with frequency, which is either magic really advanced technology, or, more likely, just a wrong curve.

0 Oliver Ou over 9 years ago in reply to Clemens Ladisch

TI__Intellectual 2845 points

Hi Clemens,
Thanks a lot for your comments.

Oliver Ou

0 Ron Michallick over 9 years ago

TI__Guru**** 166636 points

Oliver,

The TI curve is the actual Differential gain divided by Common mode gain.
The ST curve is probably 60dB divided by common mode gain.

I assure you that a 1 MHz device won't have 60dB gain beyond 1kHz.
So blindly using a constant is big time cheating or at best, ignorance.

Logic

Logic forum

a question about LM224