Analog Devices: CN0274 Reference Design for Ultralow Power Standalone Motion Switch

Kit Overview

The Analog Devices EVAL-CN0274-SDPZEVAL-CN0274-SDPZ Evaluation Board Circuit provides an ultralow power, 3-axis, motion activated power switch solution capable of controlling up to 1.1 A of load current. The circuit is ideal for applications where extended battery life is critical. When the switch is off, the battery current is less than 300 nA, and when the switch is on, it draws less than 3 μA. The circuit provides an industry leading, low power motion sensing solution suitable for wireless sensors, metering devices, home healthcare, and other portable applications.

The ADXL362ADXL362 is an ultralow power, 3-axis accelerometer that consumes less than 100 nA in wake-up mode. Unlike accelerometers that use power duty cycling to achieve low power consumption, the ADXL362 does not alias input signals by under sampling; it samples continuously at all data rates. There is also an on-chip, 12-bit temperature sensor accurate to ±0.5°.

The ADXL362ADXL362 provides 12-bit output resolution and has three operating ranges, ±2 g, ±4 g, and ±8 g. It is specified over a minimum temperature range of −40°C to +85°C. For applications where a noise level less than 480 μg/√Hz is desired, either of its two lower noise modes (down to 120 μg/√Hz) can be selected at a minimal increase in supply current.

The ADP195 is a high-side load switch designed for operation between 1.1 V and 3.6 V and is protected against reverse current flow from output to input. The device contains a low on-resistance, P-channel MOSFET that supports over 1.1 A of continuous load current and minimizes power losses.

This circuit uses the EVAL-SDP-CS1ZEVAL-SDP-CS1Z (should be purchased seperately) System Demonstration Platform (SDP-S) evaluation board and the EVAL-CN0274-SDPZEVAL-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-SDPZEVAL-CN0274-SDPZ contains the circuit to be evaluated and the EVAL-SDP-CS1ZEVAL-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-CS1ZEVAL-SDP-CS1Z.

Key Applications: Access Control, Asset Tracking, Home Healthcare, Patient Monitoring