Battery & Power Supply Considerations by Prof. Bitar
Q1: What Customer Requirements often affect the choice of power supply? • Stationary or Portable • Operation Time • Temperature Range of Operation • Size / Shape / Weight Requirements
Q1: What System Requirements often affect the choice of power supply? • Operating Voltage(s) • Voltage Tolerances (+/- 5%, 10%, etc) • Current Requirements
Example: Proximity AlarmGoes off if someone is in your space! IR Sensor & LED Op-Amp Gain / Filter Micro- Controller Power Transistor Vibration Motor
Voltage and Current Requirements per Component Q: Bases on these specifications, what operating voltage should we choose? Hmm… Q: What current must be supplied?
What voltage do we operate at? • Find a practical voltage that all components can function at. • Not always possible. • May require choosing a voltage larger than the largest requirement and REGULATING down to the smaller values. • May require finding different components.
What current is required? • How do you determine the amount of current that a power supply or battery needs to provide?
If batteries are required, what must be considered? • Voltage Range (Full Charge to Discharge) • Number of Cells Required • Battery Life (ie. mA Hr Capacity) • Rechargeable vs. Non-Rechargeable • Chemistry (Alkaline, Zinc, Lead Acid, NiCd, NiMH, etc…) • Temperature Range • Size / Weight / Cost
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