21 Feb
2010
21 Feb
'10
7:12 p.m.
On 21 Feb 2010 at 18:28, Tony Duell wrote:
Any particular reason why? I wouldn't have thpught
it was much more
work to solder a pair of 14 pin DIPs (2 off '38) rather than a single
20 pin device (I asusme that's the pacakge of the '760). If you don't
need gating in the final bufffers, can't you use the '06 or '07, which
would give you 6 signal drviers in a 14 pin package?
It has to do with dedicating the real-estate to what amounts to 26
open-collector outputs (by ignoring some options, I could get it down
to 24). That's 7 7438's. I may go with using the 7407s, though. At
least they're commodity and easy to find if they need replacing. The
package count (5 vs. 4 for octal buffers) difference is negligible.
Since there's going to be only one controller per drive, I could also
revert to plain old totem-pole output buffers as well, as the
controller will probably be mounted right on the drive with only a
few inches of cable. That broadens the array of choices
considerably.
Looking at the specs, you're right--the termination is 220/330.
--Chuck