User's Manual
Page 16 of 20 ANT C7 RF Transceiver Module
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While these current values include the contribution of the radio
and
the serial interface they do not include the
base (idle) current. To calculate the average current consumption of for a specific message rate please see the
sample calculation below.
AverageBurstCurrent
For practical purposes power consumption in burst mode is reported as an average current when bursting at a
specific bit rate and using a specific serial interface. Please note that the bit rate of the burst is a function of the
serial communication. The table below lists the continuous average current consumption while bursting.
Measured with T
A
= 25°C and V
CC
= 3 V. Output power set at 0dBm
Symbol Description
Average
Current
Units
I
burst_20kbps_byte
Continuous bursting at 20kbps in byte synch mode
9.0 mA
I
burst_7.5kbps_bit
Continuous bursting at 7.5kbps in bit synch mode
8.2 mA
I
burst_20kbps_57600_async
Continuous bursting at 20kbps in 57600 baud async
mode
8.7 mA
I
burst_20kbps_50000_async
Continuous bursting at 20kbps in 50000 baud async
mode
8.4 mA
I
burst_13.8kbps_38400_async
Continuous bursting at 13.8kbps in 38400 baud async
mode
7.9 mA
I
burst_8.4kbps_19200_async
Continuous bursting at 8.4kbps in 19200 baud async
mode
7.0 mA
3.6 Calculating the Average Current Consumption and Battery Life
The average current for a particular application will be a function of the message period, type and serial interface.
By using the values listed in the tables above, the average current can be calculated using the following formula:
I
AVE
= (I
MSG
X R
MSG
) + I
IDLE
where:
I
AVE
– Average current consumption.
I
MSG
– Current per message
I
IDLE
– Base or idle current
For example, given an ANT node that transmits broadcast data over a bi-directional channel at 0.5Hz using a byte
synchronous serial interface, the continuous average current can be calculated as follows:
I
AVE
= (49 X 0.5) + 0.91 = 25.41µA
To calculate the expected battery life of a system, the battery capacity and usage model must also be considered.
The following formula can be used (please note that this considers the current consumed by the ANT part of the
system only):
T
BAT
C
BAT
· T
Operation Cycle
T
Active
· I
Ave
T
Idle
·I
Idle