1. Battery & Power Supply Considerations by Prof. Bitar

2. Q1:What Customer Requirements often affect the choice of power supply? Stationary or PortableStationary or Portable Operation TimeOperation Time Temperature Range of OperationTemperature Range of Operation Size / Shape / Weight RequirementsSize / Shape / Weight Requirements

3. Q1:What System Requirements often affect the choice of power supply? Operating Voltage(s)Operating Voltage(s) Voltage Tolerances (+/- 5%, 10%, etc)Voltage Tolerances (+/- 5%, 10%, etc) Current RequirementsCurrent Requirements

4. Example: Proximity Alarm Goes off if someone is in your space! IR Sensor & LED Op-Amp Gain / Filter Power Transistor Vibration Motor Micro- Controller

5. Voltage and Current Requirements per Component ComponentVccIcc Sharp IS417F IR Sensor 4.5 to 16V 3.5mA (typical) 7.0mA (max) LED 1.7 to 4.5V (depends on color) 20mA per LED (typical) LM358 Op-Amp3 to 32 V 0.7 to 3mA (depending on Vcc) TI MSP430 Microcontroller 1.8 to 3.6V 1.2 to 370uA (depends on mode & clock freq.) Vibration Motor (Jameco) 1.3 to 3.0V (typical)50 to 100 mA Q:Bases on these specifications, what operating voltage should we choose? Hmm… Q:What current must be supplied?

6. What voltage do we operate at? Find a practical voltage that all components can function at.Find a practical voltage that all components can function at. Not always possible.Not always possible. May require choosing a voltage larger than the largest requirement and REGULATING down to the smaller values.May require choosing a voltage larger than the largest requirement and REGULATING down to the smaller values. May require finding different components.May require finding different components.

7. What current is required? How do you determine the amount of current that a power supply or battery needs to provide?

8. If batteries are required, what must be considered? Voltage Range (Full Charge to Discharge) Voltage Range (Full Charge to Discharge) Number of Cells Required Number of Cells Required Battery Life (ie. mA Hr Capacity) Battery Life (ie. mA Hr Capacity) Rechargeable vs. Non-Rechargeable Rechargeable vs. Non-Rechargeable Chemistry (Alkaline, Zinc, Lead Acid, NiCd, NiMH, etc…) Chemistry (Alkaline, Zinc, Lead Acid, NiCd, NiMH, etc…) Temperature Range Temperature Range Size / Weight / Cost Size / Weight / Cost

9. Battery Specifications

10. Battery Capacity

11. Battery Discharge (Under Constant Current Load)

12. If an AC to DC power supply is required, what must be considered? Input Voltage (120VAC, 60Hz …) Output Voltage (No Load and Full Load) Maximum Output Current Line & Load Regulation Voltage Ripple Size / Weight / Cost