On Sat, 06 Dec 2008 09:16:03 -0800, Peter Bennett
wrote:

On Sat, 06 Dec 2008 08:27:06 +0000, Eeyore
wrote:



Peter Bennett wrote:

"gore" wrote:

I work at an electronics contract manufacturimg facility. We do work for
several companies and I wonder why they use different labels on the
schematics and pcb's to refer to IC's. Some of them have a U1, an A1, and
X1, or an IC1. Why do they do this? Is there a standard used to label IC's
in a schematic? Just curious why this is.

The standard reference designator for integrated circuits is "U" -
anything else is wrong! ( IMHO :-) )

And what does U stand for ? Probably the stupidest choice ever aside from Q.

Graham

Perhaps U = Unit?

I think that was the origin. That's distinct from A, Assembly, which
has its own BOM. A Unit can not be disassembled.

Formal military systems often used nested designators: A3A6R41
uniquely located a resistor in a radar system. Some of the older HP
schematics used this convention, too.


John