Good schematic checklist

I'm looking for a good schematic capture checklist to use when reviewing schematics. This is for the usual issues such as check that you don't have similar but different nets (e.g. GND and GROUND) that are separate and style/readability issues (e.g. no 4-way ties). Either your list or a link to an external one would help.

For what it's worth, I'm using DX Designer, so if you have specific checks you run, let me know about that too.

Answer

A list I use for Multisim:

• Do all tantalum caps on rails have at least ~20% overhead? No 25V caps on 24V lines?


• Are there bypass caps on the power rails of every chip? Even the ones that don't look like chips, like regulators?


• Are there filters on every transistor gate/base? Even the ones in processors?


• Are there filters on A/D converter pins?



• Are there pullups or pulldowns on every pin where it could matter? Look especially for diodes driving processor inputs or transistor gates, or hanging off an input to the board. Also, outputs of comparators.


• Is there impedance on every pin feeding directly into a processor from off-board? A transistor? Something to eat noise and keep it from frying your chip?


• Do you have test points on all rails and signals of interest? Including at least one debug pin off any processor?


• Is there an LED to indicate power to the board? A second LED, processor controlled, for blink codes?


• Is there too much cap on any power rail? Switching regulators have a limit on how much cap they can pull up.


• Are all op-amps negative feedback, and all comparators positive feedback? (Obviously there are exceptions to this, I just find it a useful basic rule to check in my applications.)


• Are all op-amp and comparator power rails connected in the correct polarity?


• Are there any capacitors or zeners directly on the output of an op amp? Should be impedance between.


• Are all unused op-amps and comparators tied down properly? Tie op-amp outputs to the negative input, and tie the positive input to common. Tie to common all pins on an unused comparator.


• Do all optocouplers have resistors and caps in parallel with their diodes, for noise immunity?



• Make sure all user accessible power rails are short-circuit protected.