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     Electronics Design Checklist

             This checklist is for electronic designers and technicians who would like to work with a detailed checklist to meet their specific
             needs. There are many details that go into making a first-run design a success.

             The following are the related subjects to be reviewed at a schematic level:
             1. The schematics drawing
             2. Component choice and pin out assignment
             3. Electronic design consideration
      How to use this checklist:

             1. Copy the file to your archive/templates
             2. Edit to include/exclude the elements that are important for you
             3. Once a failure occurs, update the checklist
             4. Share it with your colleagues.

      The Schematics drawing

              File name on each sheet
              Minimum number of characters in values
              Consistent character size for readability
              Schematics printed at a readable scale
              All components have reference designators
              Every component has a value
              Every component has a part name (except resistors, capacitors etc.)
              Every net has a name
              Special information for a component
              Polarized components connections checked
              Power and ground pins shown (preferred) or listed for each component
              Check hidden power and ground connections (they are the source for many troubles)
              Title block completed for each sheet
              All test points and jumpers are marked clearly and have reference designator
              Check that all required options appear clearly on the drawing
              Check connectors and on-board elements pin out
              Ensure socket pins are marked if in use

Component choice and pin out

Mating connectors on different assemblies checked for same pin out
              Oscillators checked for reliable startup
              Automotive powered devices must withstand 60 to 100 volt surges
              Check for voltage transients and high voltages on FET gates
              Ensure resistors are operating within their specified power range plus safety factor
              Resistor power ratings derates for elevated ambient temperatures
              Electrolytic/tantalum capacitor temperature/voltage derating sufficient for MTBF
              Low impedance sources driving tantalum caps can cause premature failure
              Check PLD pin outs each time a PLD is recompiled
              Recommended component reference designators (add/remove at your convenience):
                       • R              fixed resistor
                       • RN           resistor network
                       • RV            variable resistor
                       • RL            relays
                        C              capacitor (fixed or variable)
                       • L               inductor, choke
                       • Q              transistor, FET, SCR, TRIAC
                       • D, CR      diode, rectifier, Zener, varicap, LED
                       • VR, LM     voltage regulator
                       • U              integrated circuit
                        J              socket, jack (female) OR the half that is stationary
                       • P              plug (male) OR the half that is attached to a cable/wire
                       • JP            jumper (pins, trace, or wire)
                       • X              crystal
                       • S, SW     mechanical switch
                       • F              fuse
                        FL            filter
                       • T              transformer
                       • TP           test point
                       • KB           keyboard
                       • B, BT       battery

     Electronic design consideration

              Connect spare gates inputs or unused inputs to GND or Vcc
              Outside world I/O lines filtered for RFI
              All outside world I/O lines protected against electro static discharge
              Bypass capacitor(s) for each IC
              Voltage ratings of components checked
              Ensure 3.3 volt parts are 5 volt tolerant where they interface
              Verify power sequencing requirements on 5 volt and 3.3 volt rails
              Each IC has known or controlled power-up state
              Electrolytic and tantalum capacitors checked for no reverse voltage
              Ground makes first and breaks last for hot insertion
              Check for input voltages applied with power off and CMOS latch-up possibilities
              Reset circuit design tested with fast and slow power supply rise and fall time
              Check reset behavior in power cycles before the circuit is fully operational
              Check all resets for possible reset loops, especially for hot swap operations
              Enable halting watchdog timer for testing and diagnostics
              Sufficient capacitance on low dropout voltage regulators
              Capacitance and fan out limits checked for busses
              Check maximum power dissipation at worst-case operating temperatures
              Estimate total worst case power supply current
              Avoid reverse base-emitter current/voltage on bipolar transistors
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