LM13600 vs LM13700

Aaron Cram aaronc at ori.org
Tue Mar 7 22:45:36 CET 2000

danial stocks wrote:

> Yes, I actually use the LM13600 myself.. theyre much moreavailable here than
> the 13700.. does anyone know exactly what the difference is?

According to National Semiconductor's website, (http://www.national.com) the
13600 is "obsolete" and out of production.  They are still producing 13700s, so
I've decided to use these in my circuit designs.  I've found that both chips can
be hard to find.  (Digi-key has them both.)

Here's a quote from national's website:  "The output buffers of the LM13700
differ from those of the LM13600 in that their input bias currents (and hence
their output DC levels) are independent of Iabc."  I'm not sure what this means,
but after playing with a 13700 for awhile I noticed the buffer has an annoying
property of biasing the input a couple of volts toward negative.  Maybe a 13600
wouldn't do that, but I just use a JFET op-amp for a buffer in DC circuits, the
high impedence seems to affect the transconductance less anyway.  AFAIK, the OTA
parts of the 13600/13700 are identical.

Hope this helps!


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