Q
Many digital-output accelerometers have built-in activity detection. What makes
the XL362 a better motion switch than others?
A
The activity (and inactivity) detection on other accelerometers is reported as
an interrupt to a host processor: that is, an interrupt line pulses high and
must be responded to by a microcontroller before the next detection can occur.
This means that while the accelerometer is polling for activity and inactivity,
a microcontroller must be alert (read: consuming power) to identify and clear
interrupts.
In addition to its ultralow power consumption, the ADXL362 has two new features
that make it an ideal motion switch. First, it is capable of clearing its own
interrupts without processor intervenion. Second,it can be configured to report
its motion status via a pin state: the pin is
high if in motion and low if not (or vice versa).
The combination of these features enables the ADXL362 to directly drive a
switch, such as the ADP195 or a simple FET, and thereby manage power to
downstream circuitry – completely autonomously, and all while consuming only a
few uA (or less).