1. D.H.S. Digijock Home Security
ECE477 – Team 7:
Linda Stefanutti
Zach Smith
Stuart Pulliam
Will Granger

2. Summary: Reliability and safety analysis: Criticality
Components considered
Failure modes:
Causes
Effects
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3. Components considered
Microcontroller (MC9S12)
Voltage translator (74LVC8T245)
Voltage regulators
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4. Criticality High criticality: detecting smoke
Medium: inability to activate alarm
Low: user inconvenience
Microcontroller: high
Voltage regulators: 1 high, 1 medium
Voltage translators: medium
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5. Microcontroller Predicted number of failures (λp)
C1 (die complexity): 0.12 (16-bit MOS MCU)
πT (temp coeff.) : 0.49 (45 degrees Celsius)
C2 (const) : (hermetic SMT, < 60 pins)
πE (envir. const) : 2.0 (ground fixed)
πL (learning factor) : 1.0 (>2 years)
πQ (quality factor) : 10 (commercial grade)
λp = (C1xπT+C2xπe)xπqxπl = failures/106 hours
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6. Voltage translator Predicted number of failures (λp) :
C1 (die complexity): .01 (digtl MOS <100 gates)
πT (temp coeff.) : 0.49 (45 degrees Celsius)
C2 (const) : (hermetic SMT, 24 pins)
πE (envir. const) : 2.0 (ground fixed)
πL (learning factor) : 1.0 (>2 years)
πQ (quality factor) : 10 (commercial grade)
λp = (C1xπT+C2xπe)xπqxπl = failures/106 hours
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7. Voltage regulators Classification: low frequency diode
Predicted number of failures (λp)
Λb(base failure rate) : (voltage reg)
πT (temp coeff.) : 1.5 (45 degrees Celsius)
πS(electrical stress factor) : 1.0 (voltage reg)
πC (contact constr. factor) : 1.0 (metalurgically bonded)
πQ (quality factor) : 6.0 (plastic)
πE (envir. const) : 6.0 (ground fixed)
λp = λbπTπSπCπQπE = failures/106 hours
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8. Failure modes/ effects
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9. Questions?
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