U - any unrepairable subassembly (or complex component that would not have been integrated 50 years ago) 8-)
I've also seen an x as a prefix for socketed parts e.g., xU14.
I hate *IC* as much as I hate *CR*
--just takes up more real estate on the schematic & silkscreen.
Tim's points at the proper solution: Set up a playbook within your organization and make sure everybody sticks to it. Even if it is a foolish standard, it is THE standard. 8-)
Currently some friends and I discussing what kind of reference designators should be choosen for international designs. (circuit diagrams that are common for people from US, Europe and Asia)
From this document:
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I read for example: U - integrated circuit X - subcircuit
but in several english journals often "IC" is used for a integrated circuit and "X" for connectors. (and here in Germany we use different designators and also symbols).
What is the right (best) way? Not only for that two, for all commonly used components.
B RF beads C Capacitors D Diodes J Connectors JP Other connectors (Usually config Jumpers etc) K Relays L Inductor M Other elctro-dynamic P P1 mates to J1 if the schematic covers 2 PCBs Q Transisors R Resistors S Switches T Transformers U ICs W Mystery components X Mounting holes (When needed for making grounds) Z Other impedance devices.
Everyone knows what an IC is, roughly, so the technician will know what to look for. Transistors? TR of course, same reason. Relay- RL. You've got to think about Fred with his head in the box, the works hot and pounding around him, and the production manager screaming at him to fix it. Of course, it's never MY designs they are fixing ;) But anyway, they are mostly plugging the board, not fixing it.
Space on the PCB is largely irrelevant these days- I no longer put component designations on the PCB as there simply isn't room, 0603s and all that. Much better a big paper printout with the designations bang on each resistor, cap etc.
Of course, if you have more than 26 kinds of component, you will need multiple letters anyway...
You get 27 symbols that you can choose from. As a result I have to say "nonsense you can have all the way up to 27 kinds of components".
Or:
You could use the location in mils from the fid as the reference like this for a resistor: X10752Y21623 if it is (10.752,21623) from the lower right corner of the PCB.
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