User Manual

MPR/MIB User’s Manual
Wireless Sensor Networks
Doc. # 7430-0021-06 Rev. A Page 22
Table 6-3. Estimate of battery life operation for a Mote.
SYSTEM SPECIFICATIONS
Currents
Processor
Example Duty
Cycle
C
urrent (full operation)
8 mA 1
C
urrent sleep
8
µA
99
Radio
C
urrent in receive
8 mA 0.75
C
urrent transmit
12 mA 0.25
C
urrent sleep
2
µA
99
Logger Memory
W
rite
15 mA 0
R
ead
4 mA 0
Sl
eep
2
µA
100
Sensor Board
Current
(full operation)
5 mA 1
C
urrent sleep
5
µA
99
Computed mA-hr used each hour
Processor
0.0879
Radio
0.0920
Logger Memory
0.0020
Sensor Board
0.0550
Total current (mA-
hr) used
0.2369
Computed battery life vs. battery size
Battery Capacity (mA-
hr)
Battery Life
(months)
250
1.45
1000
5.78
3000
17.35
X NOTE: In most Mote applications, the processor and radio run for a brief period of time, followed by a
sleep cycle. During sleep, current consumption is in the micro-amps as opposed to milli-amps. This
results in very low-current draw the majority of the time, and short duration spikes while processing,
receiving, and transmitting data. This method extends battery life; however, due to the current surges, it
reduces specified battery capacity. Battery capacity is typically specified by the manufacturer for a
constant nominal current drawn.
6.2 External Power
The MICA2 and MICAz can be externally powered through either:
1. The 51-pin connector will supply power and ground to the unit. Refer to connector
description.
2. The 2-pin Molex connector. Molex part number 53261-0290, Digi-Key part number
WM1753-ND. (See Figure 6-4 below.)