Minimizing Power Consumption of iMEMS® Accelerometers - 解决方案

Basic Methods
There are three basic methods to reduce power
consumption:
• Lower the supply voltage
• Turn off the accelerometer when measurements are
not taking place
• Use clever software
All of the techniques outlined in this application note are

no more than extensions of these methods

• Lower the supply voltage
• Turn off the accelerometer when measurements are
not taking place
• Use clever software
All of the techniques outlined in this application note are
no more than extensions of these methods
In iMEMS accelerometers, the turn-on time is mainly a
function of the bandwidth. While higher bandwidths will
allow lower power operation (due to faster power
cycling rates), doing so generally results in more noise.
Many systems include an antialiasing filter between the
accelerometer and the A/D converter. The time constant
of this antialiasing filter must also be considered when
power cycling.
Table I shows the approximate turn-on time (including
the internal low-pass filter) for several accelerometers.
Faster turn-on times allow the user to very quickly turn
on the accelerometer, measure the acceleration, and
then turn off the accelerometer.
where CX is in F. The 0.3 s is the turn-on time of the
accelerometer itself, while the 160 CX (or CY) term is
the settling time of the bandwidth limiting filter. Using a
0.0022 F capacitor, the turn-on time to steady state is
approximately 650 s. The analog outputs and an A/D
converter will be used, so a conversion time of 25 s
must be added. So the total ontime is 675 s.

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