User Manual

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DE-ACCM3D Buffered ±3g Tri-axis Accelerometer

Features

Triple axis ±3g sense range

Up to 360mV/g sensitivity

500Hz bandwidth

Operating voltage 3.5V to 15V (onboard regulator)

Operating voltage 2.0V to 3.6V (without regulator)

3.3V regulator can power external microcontroller

Reverse voltage protection

Output short protected

Standard DIP-16 form factor

Integrated power supply decoupling

Draws 0.9mA

Can accurately drive 500

Ω

loads

Applications

Motion, tilt and slope measurement

Device positioning

Shock sensing

Vehicle acceleration logging

General Description

The DE-ACCM3D is a complete 3D ±3g

analog accelerometer solution. It features

integrated op amp buffers for direct connection

to a microcontroller’s analog inputs, or for

driving heavier loads.

The onboard 3.3V regulator and decoupling

capacitor give you great flexibility when

powering the device, and can also be

bypassed for operation down to 2.0V.

The DE-ACCM3D is designed to fit the DIP-16

form factor, making it suitable for

breadboarding, perfboarding, and insertion

into standard chip sockets.

It is based on the Analog Devices ADXL330

for superior sensitivity and tighter accuracy

tolerances

Summary of content (5 pages)

PAGE 1
DE-ACCM3D Buffered ±3g Tri-axis Accelerometer General Description The DE-ACCM3D is a complete 3D ±3g analog accelerometer solution. It features integrated op amp buffers for direct connection to a microcontroller’s analog inputs, or for driving heavier loads. The onboard 3.3V regulator and decoupling capacitor give you great flexibility when powering the device, and can also be bypassed for operation down to 2.0V.
PAGE 2
Measuring acceleration and tilt The voltage outputs on the DE-ACCM3D correspond to acceleration being experienced in the X, Y and Z directions. The output is ratiometric, so the output sensitivity (in mV/g) will depend on the supply voltage. Sensitivity and accuracy Here are some typical sensitivity values for common operating voltages: Operating voltage Sensitivity 3.6V 360 mV/g 3.33V 333 mV/g (default when using onboard regulator) 3.0V 300 mV/g 2.
PAGE 3
Example calculations Voltage to acceleration example: ”With the 3.3V supply, the X output reads 2.06V. What acceleration does this correspond to?” At 3.3V, the 0g point is approximately 1.66V 2.06V – 1.66V = +0.40V with respect to the 0g point At 3.3V, if sensitivity is 333mV/g, 0.40 / 0.333 = 1.20g Therefore the acceleration in the X direction is +1.20g Acceleration to voltage example: ”I am powering the DE-ACCM3D with 2.0V. What voltage will correspond to an acceleration of -0.
PAGE 4
Performance features Output buffers A bare accelerometer chip has an output impedance of 32kΩ, which is unsuitable for obtaining reliable measurements when connected to an analog to digital converter. On the DE-ACCM3D, a quad rail to rail operational amplifier buffers the outputs from the ADXL330, greatly reducing output impedance. The absolute maximum load beyond which accuracy begins to seriously suffer is 3.3mA, or 500Ω.
PAGE 5
Powering external devices It is possible to use the DE-ACCM3D’s voltage regulator to power external devices that require 3.3V, such as a low voltage microcontroller. These devices must be extremely low power so as to not overload the regulator! The maximum current that can be drawn in this way is 50mA, but ideally you should try keep things below 10mA. This diagram shows how to connect up an example microcontroller and all 3 axes.