Schematic Review Criteria

Presented below is a list of things that I check prior to considering a schematic complete and correct. This list is by no means exhaustive, but I find that it catches the majority of problems in my designs as well as in designs that I am reviewing. This list assumes you are in the prototyping stage. If you are designing for high volume there are likely other considerations to factor in.

1. Make sure bypass capacitors are included for all ICs (that need them)
2. Power input capacitors supplied
3. Output capacitors from all regulators (if needed)
4. All selectable inputs to ICs understood and connected correctly (dividers for comparator setting, select lines for chip modes, resistors for DC-DC voltages etc)
5. All polarized components are appropriately marked (especially capacitors)
6. Document the usage/purpose of any 0 ohm and DNI resistors
7. Check IC voltage requirements vs input voltages. Look especially for 3.3V parts connected to 5V power.
8. Terminate all pins that require termination
9. Connector pinouts documented and match the system specification.
10. Check crystal capacitors match crystal selected.
11. Check that in circuit programming of programmable ICs will not damage nearby chips
12. Check voltage ratings on capacitors.
13. Check polarity/ type of all input lines (open collector etc).
14. Include ESD protection if needed
15. Check that fuses are properly sized for the circuit they are protecting
16. Identify connections where it would be desirable to be able to reconfigure using DNI/0 ohms (serial lines etc)
17. Identify and confirm special passive requirements (specific ESR etc)
18. Determine if isolation is required for any portions of the circuit
19. If isolation, check that isolation borders are not crossed
20. Check temperature ratings on components. For components which dissipate significant power make sure the temperature rise doesn't exceed the range at full ambient temperature range.
21. Check that all op amps have sufficient bandwidth
22. Sort out Analog and digital grounds
23. Check serial direction! If there is any doubt, include 0 ohms/ DNIs to correct
24. Check Max233 pinout vs package. This one is weird since it differs from dip to so.
25. Do all lines that need pullups/ pulldowns have them?
26. Do any config lines that might need to be changed have pads available to correct without rework.
27. Are all op amps used. Connect unused op amp sections to avoid noise and power problems.