Schematics nomenclature

DaveC

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Jul 4, 2016, 11:27:01 AM7/4/16

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http://imgur.com/KWFIN1H

Pins 12 and 13 have a little triangle next to the pin; pins 1, 2, 15, 16 have
what looks like an “n”; 3 and 14 have an “x”.

What’s the meaning of these marks?

Thanks.

DaveC

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Jul 4, 2016, 11:28:07 AM7/4/16

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From service manual for HP 34401A DMM.

-=-=-=-

Tom Del Rosso

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Jul 4, 2016, 12:49:23 PM7/4/16

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That's the IEEE standard schematic notation touted by TI in the 80's.
The downward sloping triangle means logical inversion, or active-low. I
don't remember the others.

N_Cook

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Jul 4, 2016, 1:49:16 PM7/4/16

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In that case "x" means don't care

Tauno Voipio

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Jul 4, 2016, 2:11:25 PM7/4/16

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The 'n' pins are non-logic signals. The 'x' pins are power supply pins,
see the chip data sheet.

--

-TV

Don Y

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Jul 4, 2016, 2:22:01 PM7/4/16

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The little triangle (sort of like half an arrowhead?) denotes active low
(what used to be indicated by a "bubble"). The tip of the arrow indicates
the direction of signal flow. Can appear on a gazinta or a cumzouta.

A (real!) triangle inside the device outline denotes a dynamic/clock input
(edge)

The "n" (actually, more like an upside down U) denotes an analog signal
(look at the device and you can see why this is so!) when encountered on
a digital signal; a '#' indicates a digital signal when encountered on
an analog signal.

The 'x' indicates a "non-logic" signal (in yor case, the reference gnd)

There are other markings that indicate postponed outputs, tristate outputs,
open-collector, open-emitter, hysteresis, etc.

DaveC

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Jul 4, 2016, 3:44:53 PM7/4/16

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On 4 Jul 2016, gfre...@aol.com wrote:

> It looks like they are saying these pins go to the AC ground bus.

As denoted by the huge triangle (left of the junction) and “ACGND”...

Why would the designers put those small triangles there if the connection and
label already make this obvious?

DaveC

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Jul 4, 2016, 3:45:30 PM7/4/16

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On 4 Jul 2016, Don Y wrote:

> The "n" (actually, more like an upside down U) denotes an analog signal
> (look at the device and you can see why this is so!) when encountered on
> a digital signal; a '#' indicates a digital signal when encountered on
> an analog signal.

??

"when encountered on”? So both of these pins are mixed-signal? “n” is
mostly-digital and # is mostly-analog? (c;

DaveC

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Jul 4, 2016, 4:04:13 PM7/4/16

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Datasheet:
http://www.analog.com/media/en/technical-documentation/data-sheets/AD7524.pdf

Pins 12, 13 are latch enables that aren’t used so tied to ground. The tiny
“triangles” are probably enable-low indicators.

Still not sure about “n”, “#”, “x”...

-=-=-=-

k...@attt.bizz

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Jul 4, 2016, 4:40:14 PM7/4/16

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Which triangles are you talking about? The triangles on the power
pins simply denote a global (power) connection. That's all.

The wedges where the pins connect to the body denote an inverted pin,
or a "logic low active" signal. The fact that these are grounded
simply means that these signals are tied "active".

DaveC

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Jul 4, 2016, 5:11:46 PM7/4/16

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On 4 Jul 2016, k...@attt.bizz wrote:

> The wedges where the pins connect to the body denote an inverted pin,
> or a "logic low active" signal. The fact that these are grounded
> simply means that these signals are tied "active".

Yeah, those.

Thanks.