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Reference designators in circuit diagrams

Discussion in 'Electronic Design' started by Matthias Weingart, Jan 31, 2005.

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  1. 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:
    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.

  2. Tim Shoppa

    Tim Shoppa Guest

    My engineering organization, after extensive meetings and discussions,
    reached this compromise:

    Use "U" for integrated circuits on the right side of the schematic.

    Use "IC" for integrated circuits on the left side of the schematic.

    Use "X" for IC's that interface to a balkanized sub-organization. Use
    "X" for connectors in the rest of the circuit.

  3. Ken Smith

    Ken Smith Guest

    I suggest:

    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.
  4. JeffM

    JeffM Guest

    discussing what kind of reference designators
    U - any unrepairable subassembly
    (or complex component that would not have been integrated 50 years
    ago) :cool:

    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. :cool:
  5. Rich Grise

    Rich Grise Guest

    A Assembly
    B Blower/motor
    C Capacitor
    D Diode
    E Tie point/test point
    F Fuse
    G Galvanometer/other
    H - ?
    I Indicator
    J Jack
    K Relay
    L Inductor
    M Motor
    O - ?
    P Plug
    Q Transistor
    R Resistor
    S Switch
    T Transformer
    U IC
    V Valve (electron tube)
    W Cable
    X Crystal/Resonator/Subcircuit
    Y Crystal
    Z - Any network that presents an impedance.

    Have Fun!
  6. Fred Bartoli

    Fred Bartoli Guest

    Any complex unrepairable subassembly is refrenced as Uhh...
  7. Paul Burke

    Paul Burke Guest

    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...

    Paul Burke
  8. Ken Smith

    Ken Smith Guest

    If you count only the clear shape differences:


    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".


    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.
  9. Thanks to all. It seems that everybody is doing his own stuff.

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