Specifications
Data sheet
BMA220
Page 35
BST-BMA220-DS003-08 | Revision 1.15 | August 2011 Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
6.3 Low-power mode and suspend mode
The BMA220 is optimized for low power consumption. Note: Simply switching-off of the power
supplies (V
DDD
and/or V
DDA
) is not a defined low-power mode.
The deactivation of V
DDD
while V
DDA
is active (or vice versa) is not recommended for permanent
operation. With respect to the application it might be useful to switch-off V
DDIO
while V
DDD
and
V
DDA
are active. This condition is supported and will lead to a reduction of current consumption.
The sensor register map will be reset.
To reduce current consumption in a defined way, the BMA220 supports two energy saving
modes: a suspend mode and a low-power mode.
During normal mode operation, all analog modules are held powered-up and the clock for all
digital modules is active. During low-power mode, the analog modules in the rate channel are
held powered down and the clock of the digital rate, filter and trimming modules is gated. The
average typical current consumption during sleep phase (i
low_power_mode
) can be estimated by the
following equation:
First approximation: i
sleep
= i
suspend
Ø typ.
awakesleep
activeactivesuspendsleep
epowerlow
tt
itit
i
mod__
For sleep phase time setting (t
sleep
) refer to chapter 4.1.2 table 3.
For approximate awake phase time (t
awake
) refer to chapter 4.1.3 table 4.
For current consumption in normal mode (i
active
) refer to chapter 1.
For current consumption in suspend mode (i
suspend
) refer to chapter 1.
Example: Bandwidth (BW) = 1kHz, nominal supplies
resulting awake phase for 1
st
data sample (t
awake
) = 1190μs = 1.190ms
resulting sleep time (t
sleep
) = 50 ms
Ø typ.
µA
msms
µAmsµAms
tt
itit
i
awakesleep
activeactivesuspendsleep
epowerlow
8,6
190,150
250190,1150
mod__