Electronic – Are there conventions for representing hierarchical components on a schematic

designschematics

Say I'm designing a device with a lot of repeated elements, like an 8-channel audio mixer. Each channel will have functional units that are identical and repeated, for example, an amplifier.

To keep the top-level schematic readable, my schematic capture software allows schematics to be hierarchical, where the top schematic has symbols which represent subcircuits.

An example:

schematic

simulate this circuit – Schematic created using CircuitLab

What conventions are there for visually representing this? Are there conventions to give the reader of a schematic a hint that A1, A2, and A3 are not discrete components or ICs, but a circuit defined on another page?

What conventions exist for naming (for printing on the PCB) the discrete components that compose these sub-circuits? Would it make sense to concatenate the name of the symbol and the components, so in the example above I'd end up with A1R1, A1R2, A2R1, A2R2, …? Is there a conventional prefix for the names of the symbols, A1-A3 in the example, which hints at their nature? (As C1 suggests a capacitor, etc…)

Best Answer

Sadly there is no accepted standard. As with most schematics, whatever works to convey the information best for your group is all that matters.

Each tool is also going to implement hierarchical designs in different ways. Altium for example, allows you to add suffixes to reference designators. One way for you to do it would be to have R1_1, R1_2, R1_3 .. U1_1 U1_2 U1_3.

http://techdocs.altium.com/display/ADOH/Multi-Channel+Design+Concepts

It's a handy feature in theory but sacrifices the ability to set reference designators based on PCB placement which is much handier when you need to change out R1_2 but now have no idea where it is without searching your layout.

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