RCD Laser SystemCorey Lane, Ryan Scott, Danny Barjum

MicrocontrollerParameter Description Value CommentsC1 Die Complexity .14 8-bit CMOS

πT Temperature Coefficent

1.5 Assumed based on average microcontroller conditions

C2 Package Failure Rate

.013 28-pin nonhermetic

πE Environmental Constant

2 Fixed Ground

πQ Quality Factor 10 Commercial Product

πL Learning Factor 1 Over 2 years old

λp = (C1πT + C2πT) πQ πL = 2.36 failures/10^6 hoursMTTF = 1/ λ p = .4237e6 hours to failure

Bluetooth ModemParameter Description Value CommentsC1 Die Complexity .16 Assuming 10k-30k

transistors

πT Temperature Coefficent

1.5 Assumed based on average IC conditions

C2 Package Failure Rate

.0025 6-pin nonhermetic

πE Environmental Constant

2 Fixed Ground

πQ Quality Factor 10 Commercial Product

πL Learning Factor 1 Over 2 years old

λ p = (C1πT + C2πT) πQ πL = 2.45 failures/10^6 hoursMTTF = 1/ λ p = .4082e6 hours to failure

RF RecieverParameter Description Value CommentsC1 Die Complexity .08 Assuming 3k – 10k

transistors

πT Temperature Coefficent

1.5 Assumed based on average IC conditions

C2 Package Failure Rate

.0013 3-pin nonhermetic

πE Environmental Constant

2 Fixed Ground

πQ Quality Factor 10 Commercial Product

πL Learning Factor 1 Over 2 years old

λ p = (C1πT + C2πT) πQ πL = 1.226 failures/10^6 hoursMTTF = 1/ λ p = .8157e6 hours to failure

Voltage RegulatorParameter Description Value Commentsλ d Base Failure

Probability.002 Voltage Regulator

πT Temperature Coefficent

3.9 Assumed maximum operating temperature of 70˚C

πS Stress Coefficent 1 Voltage Regulator

πC Contact Construction Factor

1 Metallurgically bonded contact

πQ Quality Factor 8 Plastic casing

πE Environmental Constant

6 Fixed Ground

λ p = λ p πTπSπCπQπE = .3744 failures/10^6 hoursMTTF = 1/ λ p = 2.6709e6 hours to failure

Failure Modes – μC Subsystem

Failure Mode Possible Causes

Failure Effects Method of Detection

Criticality

Microcontroller doesn’t receive a signal from the RF receiver

RF Transmitter, RF receiver, uC pin

Inability to draw or select options

Observation Low

Microcontroller doesn’t receive a signal from the camera

Pixart camera, uC pin

Software will not receive new coordinates

Observation Low

Bluetooth transmitter is not transmitting data.

Battery Subsystem, microcontroller, shorted bypass capacitor, Bluetooth transmitter

Software will not receive any input

Observation Low

Failure Modes – Battery Subsystem

Failure Mode Possible Causes

Failure Effects Method of Detection

Criticality

Battery overcharge

Fuel gauge, charger , sense resistor

Heat, possible battery expansion, leakage or explosion

Observe system failure, burning

High

Battery doesn’t charge

Power supply, fuel gauge, charger , sense resistor

System doesn’t operate after battery dies

Observation, gauge LEDs

Low

Voltage regulator outputs greater than 3.3V

Voltage regulator

Damage to all logic circuits, instability

Observation Low

Voltage regulator outputs less than 3.3V

Voltage regulator

Instability or no system response

Observation Low

Criticality Definitions Low Criticality – Inconvenience to the user or failure of system.

λp = 10^6 failures/hours High Criticality – Potential to harm user.

λp = 10^9 failures/hour

Potential Improvements Independent monitoring of the battery voltage as a fail safe for

the charger. Robust battery enclosure to reduce critically of battery

overcharging. Monitor voltage regulator and shutdown system if out of range. Monitor charging power supply voltage and current. If RF data connection fails, always draw instead of never draw.