SOLAR TELEMATICS SYSTEM Reliability and Safety Analysis Craig

SOLAR TELEMATICS SYSTEM Reliability and Safety Analysis Craig Lechlitner Brian Kelley Clayton Dickemann Dan Ehrman

Block Diagram

PSSCs 1. An ability to track vehicle location using GPS. 2. An ability to receive and send CAN messages from and to other systems in the car. 3. An ability to display graphics on the LCD display. 4. An ability to respond to user input from a touchscreen. 5. An ability to store and load data to and from nonvolatile memory.

Components Chosen for Analysis • Graphics Controller (PIC 24 FJ 256 DA 210) • Communications Microcontroller (PIC 32 MX 795 F 512 H) • SRAM (IS 61 WV 102416 BLL) • 3. 3 v Switch Mode Regulator (LM 3407)

PIC 24 graphics microcontroller • High complexity (100 pin, 16 bit) • Controls LCD, touch input, audio, SRAM, SD card. Interfaces with PIC 32 λp = 3. 76 failures per 106 hours MTTF = 266, 000 hours = 30. 4 years Parameter Description Value Comments C 1 Die complexity 0. 28 16 bit microprocessor πT Temperature coefficient 0. 60 70 C Die Temperature (estimate) C 2 Pin count 0. 052 100 pin, Nonhermetic SMT πE Environmental constant 4. 0 Ground Mobile πQ Learning factor 1. 0 In production for >2 years πL Quality factor 10. 0 Commercial Product

PIC 32 communications microcontroller • High complexity (64 pin, 32 bit) • Communicates with other systems on CAN bus, GPS, sends telemetry data. λp = 4. 64 failures per 106 hours MTTF = 216, 000 hours = 25 years Parameter Description Value Comments C 1 Die complexity 0. 56 32 bit microprocessor πT Temperature coefficient 0. 60 70 C Die Temperature (estimate) C 2 Pin count 0. 032 64 pin, Nonhermetic SMT πE Environmental constant 4. 0 Ground Mobile πQ Learning factor 1. 0 In production for >2 years πL Quality factor 10. 0 Commercial Product

SRAM • 16 MBit • Holds frame buffers for LCD. • Interfaces with PIC 24. • λp = 15. 84 failures per 106 hours • MTTF = 63, 000 hours = 7. 2 years Parameter Description Value Comments C 1 Die complexity 2. 48 16 MBit, Estimate (table only goes to 1 MBit) πT Temperature coefficient 0. 60 70 C Die Temperature (estimate) C 2 Pin count 0. 024 48 pin, Nonhermetic SMT πE Environmental constant 4. 0 Ground Mobile λ Cycling induced Failure Rate 0. 0 NOT Flotex or Textured-Poly EEPROM πQ Learning factor 1. 0 In production for >2 years πL Quality factor 10. 0 Commercial Product cyc

LM 2673 Switch mode regulator • • Possible high temperature Powers everything except backlight and audio amplifier 12 -15 v unregulated input 3. 3 v, 3 Amax regulated output • λp = 0. 376 failures per 106 hours • MTTF = 2, 660, 000 hours = 304 years Parameter Description Value Comments C 1 Die complexity . 04 Estimate 101 to 1000 MOS transistors (Linear model πT Temperature coefficient 0. 60 70 C Die Temperature (estimate) C 2 Pin count 0. 0034 8 pin, Nonhermetic SMT πE Environmental constant 4. 0 Ground Mobile πQ Learning factor 1. 0 In production for >2 years πL Quality factor 10. 0 Commercial Product

Definition of Criticality levels • High - Possibility of injury to user • Medium - Renders device useless, major repairs needed • Low – Majority of device still works, easily repairable

FMCEA chart Failure mode Possible causes Effect Detection method Criticality Power supply becomes unregulated (Vout > 3. 3 v) Failure of U 5 Possible damage to most ICs, excessive heat build up, smoke and fire Observation (smell of burning electronics), probe 3. 3 v line High Only backlight works, possible heat build up, smoke and fire Observation (visual, smell High of burning electronics), probe 3. 3 v line 3. 3 v Power supply becomes Failure of U 5, D 5, C 19, shorted etc Device fails to power up Pin on either PIC 24 or PIC 32 becomes constant 1 or 0 Blown fuse due to Nothing works temporary short circuit or reverse polarity on VIN Software, poor soldering, Specific function stops failure of peripheral. working Failure to communicate Failure of U 10 (PIC 32), with other systems on CAN or U 13 (MAX 3051), bus. software in this or another system. Data in SRAM becomes Failure of U 3 (SRAM), corrupted/unreadable U 1 (PIC 24) Observation (visual) Low Observation Low - Medium Cannot control headlights, Self check wiper, vehicle direction. Cannot display battery or solar array stats, etc. Erratic data sent to LCD Observation (visual), use logic analyzer Low, can still display vehicle speed/position, vehicle will still drive. Low - Medium

Questions?