On 30 Jan 2009 11:42:30 -0500, (Samuel M.
Goldwasser) put finger to keyboard and composed:

I have a PCB with a part marked:

H721A
F749AMD

It's an 8 pin SOIC, with power (+5 VDC) at pin 8 and GND at pin 4.
Could be an op-amp or TTL based on expected function.

I'm assuming Harris - the "H" is a bit bolder than the rest.

Only a few years old, not ancient.

Google seems to have no clue except that the H721A has been asked about
on a sci* group in the past, apparently without a solution.

It really shouldn't be anything unusual or custom,

Some of it's pins are connected to the outside world via 100 ohm series
resistors. Part of an interlock on a laser.

Any info appreciated.

Thanks!

FWIW, I found this tiny snippet of info on a part that may be related
to the H721A:
http://www.partminer.com/spdetail/H723A

H723A
IC,ESD/OVERVOLT PROTECT,S

H723A
SOP-8P INTERSIL

Another clue may be this post:
http://www.sxlist.com/techref/postbo...C 071335a.txt

The author writes:

"I'm trying to find the manufacturer of a IC in the PicStart board,
it's a SO8 dual SPST switch and it's marked H721A.

I've found the analog device ADG721, but I'd like to know others
manufacturers."

Microchip's PicStart manual states that the "PICSTART Plus development
programmer features ... special circuit design techniques to enhance
ESD protection."

Here is the datasheet for the ADG721/722/723:
http://www.datasheetarchive.com/pdf-.../DSA-70382.pdf

It states that "the ADG721/ADG722/ADG723 features proprietary ESD
protection circuitry". The part is described as a "CMOS Low Voltage 4V
Dual SPST Switch".

I suspect that the H721A is in fact compatible with the ADG721.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.