CN-0274 Datasheet, PDF (5/6 Pages) Analog Devices – Ultralow Power, 3-Axis, Motion Activated Switch

Circuit Note
CN-0274
Figure 3. Photo of EVAL-CN0274-SDPZ PCB
COMMON VARIATIONS
The maximum continuous operating current of the ADP195 is
fixed at 1.1 A. For applications requiring more downstream power,
a higher current rated switch can be used in place of the ADP195.
By sacrificing approximately 15 µA of quiescent current, the
ADP197 is capable of providing 3 A of current to downstream
circuitry. For applications requiring less downstream power, the
ADP190 can be used. It has a continuous current of 500 mA
and is available in a smaller WLCSP package than the ADP195.
A second variant of the provided solution is to create a free fall
detection system. This function can be implemented using the
inactivity interrupt. When an object is in true free-fall, acceleration
on all axes is 0 g. Thus, free-fall detection is achieved by looking
for acceleration on all axes to fall below a certain threshold (close to
0 g) for a certain amount of time.
The ADXL362 functions as a free-fall detector by setting the
inactivity threshold (300 mg to 600 mg) and inactivity time
(150 ms to 350 ms). The register setting for these values varies
based on the g-range setting of the device.
CIRCUIT EVALUATION AND TEST
This circuit uses the EVAL-SDP-CS1Z System Demonstration
Platform (SDP) evaluation board and the EVAL-CN0274-SDPZ
circuit board. The two boards have 120-pin mating connectors,
allowing for the quick setup and evaluation of the performance
of the circuit.
The EVAL-CN0274-SDPZ contains the circuit to be evaluated,
as described in this note, and the EVAL-SDP-CS1Z is used with
the CN0274 evaluation software to capture the data from the
EVAL-CN0274-SDPZ.
Because the ADXL362 requires a relatively small amount of
power in both the asleep and awake states, it is possible to
power the EVAL-CN0274-SDPZ from the digital data lines
coming out of the EVAL-SDP-CS1Z.
Equipment Needed
The following equipment is needed:
• A PC with a USB port and Windows® XP or Windows Vista®
(32-bit), or Windows® 7 (32-bit)
• The EVAL-CN0274-SDPZ evaluation board
• The EVAL-SDP-CS1Z evaluation board
• The CN0274 Evaluation Software
• A power supply: 3.0 V or 2 AAA batteries.
Getting Started
Load the evaluation software by placing the CN0274 evaluation
software CD into the PC. Using My Computer, locate the drive
that contains the evaluation software CD and open the Readme
file. Follow the instructions contained in the Readme file for
installing and using the evaluation software.
Rev. A | Page 5 of 6