Download The Design Process Abstraction & Synthesis

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 Alarm
Goes off if someone is in your space!
IR Sensor
& LED
Op-Amp
Gain / Filter
MicroController
Power
Transistor
Vibration
Motor
Voltage and Current
Requirements per Component
Component
Vcc
Icc
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-Amp
3 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?
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
Battery
Specifications
Battery Capacity
Battery Discharge
(Under Constant Current Load)
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