BMA253
Data sheet
Page 16
tACTIVE
State
Active phase
Sleep phase
tSLEEP
tSLEEP
t
Figure 3: Timing Diagram for low-power mode 1/2, EDT
When (0x12) sleeptimer_mode is set to ‘1’, the equidistant-sampling mode (EST) is selected.
The use of the EST mode is recommended when the FIFO is used since it ensures that
equidistant samples are sampled into the FIFO regardless of whether the active phase is
extended by active interrupt engines or interface activity. In EST mode the sleep time tSLEEP is
defined as shown in Figure 4. The FIFO sampling time tSAMPLE is the sum of the sleep time tSLEEP
and the sensor data sampling time tSSMP. Since interrupt engines can extend the active phase to
exceed the sleep time tSLEEP, equidistant sampling is only guaranteed if the bandwidth has been
chosen such that 1/(2 * bw) = n * tSLEEP where n is an integer. If this condition is infringed,
equidistant sampling is not possible. Once the sleep time has elapsed the device will store the
next available sample in the FIFO. This set-up condition is not recommended as it may result in
timing jitter.
Sampled into FIFO
State
Active phase
Sleep phase
tSLEEP
tSAMPLE
tSLEEP
tSAMPLE
tSLEEP
tSSMP
tSAMPLE
t
Figure 4: Timing Diagram for low-power mode 1/2, EST
BST-BMA253-DS000-01 | Revision 1.0 | August 2015
Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
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