[x] mating connectors on different assemblies checked for same pinout
[x] all outside world I/O lines filtered for RFI
[x] all outside world I/O lines protected against static discharge
[x] bypass cap for each IC
[x] voltage ratings of components checked — as was not done in the on-board computer in my 1990 Geo Tracker, apparently manufactured by Mitsubishi, where capacitor C4 was rated at 47uf/50V across an automotive rail which can easily see larger spikes. Other owners reported such problems in vehicles from 1990 to 1995, with the capacitor spewing electrolyte onto the conformally coated PCB, corroding conductors in the vicinity. Hats off to Mitsubishi for ignoring a simple checklist item for five years and who knows how many hundred thousand vehicle shipments, and who knows how many in-service failures.
[x] each IC has predictable or controlled power-up state
[x] file name on each sheet
[x] dot on each connection
[x] minimum number of characters in values
[x] consistent character size for readability
[x] schematics printed at a readable scale
[x] all components have reference designators and values
[x] special PCB or parts list information entered for each component, if required
[x] polarized components checked
[x] electrolytic and tantalum capacitors checked for no reverse voltage
[x] power and ground pins listed for each component with hidden power pins
[x] check hidden power and ground connections
[x] title block completed for each sheet
[x] ground made first and breaks last for hot pluggability
[x] pullups on all open collector outputs
[x] sufficient power rails for analog circuits
[x] LM324 and LM358 outputs loaded to prevent crossover distortion
[x] amplifiers checked for stability
[x] oscillators checked for reliable startup
[x] consider signal rate-of-rise and fall for noise radiation
[x] check for input voltages applied with power off and CMOS latchup possibilities
[x] reset circuit design reliable, both glitch-free and consistent; tested with slow power supply fall time
[x] separate analog signals from noisy or digital signals
[x] ability to disable watchdog timer for testing and diagnostics and emulation
[x] sufficient capacitance on low dropout voltage regulators
[x] setup, hold, access times for data and address busses
[x] check the data sheet fine print and apnotes for weird IC behaviors
[x] determine effect of losing each of multiple grounds on a connector
[x] automotive powered devices must withstand 60 to 100 volt surges
[x] check maximum power dissipation at worst-case operating temperatures
[x] check time delays and slew rates of opamps used as comparators
[x] check opamp input over-drive response for unintended output inversion
[x] check common mode input voltages on opamps
[x] check for voltage transients and high voltages on FET gates
[x] check failure modes and effects of failed power semiconductors
[x] estimate total worst case power supply current
[x] check pin numbers of all custom-generated parts
[x] for buses, ensure bus order matches device order
[x] ensure resistors are operating within their specified power range plus safety factor
[x] resistor power ratings derated for elevated ambient temperatures
[x] electrolytic/tantalum capacitor temperature/voltage derating sufficient for MTBF
[x] check for low impedance sources driving tantalum caps which can cause premature failure
[x] avoid reverse base-emitter current/voltage on bipolar transistors
[x] use of baud rate friendly clock source for devices that have serial ports
[x] ~IOR and ~IOW strobes on UARTs are typically incompatible with timings of signals readily available on many processors
[x] ROHS compliance requirement review
[x] part obsolescence review
[x] replacement part compatibility with software requirements: “top-boot vs. bottom boot FLASH”, UART compatibility, SPI memory timing and addressing for different sized parts
[x] all PCB signal changes noted to the software geeks
[x] all no-connect pins on IC’s should be labelled NC
[x] text should not overlap wire or symbol graphics on schematics
[x] busses with off-page destinations present with title at page margin
[x] card edge connectors identify mating part
[x] page title present and consistent on all pages if not in title block
[x] under-utilization of gates on multi-gate parts checked
[x] off board connectors identify all signals even if not used on this design
[x] unpopulated parts annotated and enclosed by dashed-line box on schematics
[x] wires exist between all connected pins/ports (no direct pin/pin connections) if capture package does not like such connections
[x] symbols identify open collector/drain pins and internal pulled up/down pins
[x] clock lines with series termination and parallel termination component locations present even if not populated; zero ohm resistor for series, unpopulated parts for parallel termination
[x] avoid direct connect of mode pins or no-connect bus lines to GND or VCC so PCB rework options are maximal
[x] diagnostic resources by design (leds, serial ports, etc.) even if unpopulated by default
[x] pin names and attributes on symbols with multi-function pins should match actual design usage (I/O/Bi, Name)
[x] connect DIP switches and other grouped I/O to ports in a logical way, LS bit to LS bit, MS bit to MS bit
[x] piezo elements generate voltages (when shocked) that can destroy their drivers — check for susceptibility
[ ] miscellaneous parts on bill of materials and assembly notes for same: hardware, heat sinks, heat sink compound or composite insulators, IC sockets, consumables
[ ] assembly notes for all special operations
[ ] conformal coating
[ ] special static handling precautions required during assembly and test
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