CMA3000-D0X Series

VTI Technologies Oy

5/ 35

www.vti.fi

Doc.Nr. 8281000.12

Rev. 0.12

1

General Description

1.1

Introduction

CMA3000-D0X is a three axis accelerometer family targeted for high volume products requiring

small size, low price and low power consumption. It consists of a 3D-MEMS sensing element and a

signal conditioning ASIC in a wafer level package.

Block diagram of CMA3000-D0X is shown in Figure 1 below.

DE-

MUX

1:3

Oscillator

&

clock

Motion

detector

Free fall

detector

Reference

CSB

Control

&

INT

C/V

Analog

calibration

&

ADC

Non-

Volatile

Memory

Low-pass

Filter

Low-pass

Filter

Low-pass

Filter

SCK/SCL

MISO

MOSI/SDA

SPI

&

I2C

i/f

INT

Figure 1. CMA3000-D0X block diagram with digital SPI and I

This document, no. 8281000, describes the product specification (e.g. operation modes, user

accessible registers, electrical properties and application information) for the CMA3000-D0X family.

The specification for an individual sensor is available in the corresponding data sheet.

1.2

Functional Description

1.2.1

Sensing element

The sensing element is manufactured using proprietary bulk 3D-MEMS process, which enables

robust, stable and low noise & power capacitive sensors.

The sensing element consists of three acceleration sensitive masses. Acceleration will cause a

capacitance change that will be then converted into a voltage change in the signal conditioning

ASIC.

1.2.2

Interface IC

CMA3000 includes an internal oscillator, reference and non-volatile memory that enable the

sensor's autonomous operation within a system.

The sensing element is interfaced via a capacitance-to-voltage (CV) converter. Following

calibration in the analog domain, the signal is A/D-converted and then digitally filtered. Sensor

output is user selectable digital SPI or I

In measurement mode acceleration data can be read via the serial bus and in power down mode

the device is in-active. Other supported features are motion and free-fall detection. In these modes,

the sensor will generate an interrupt when a pre-defined condition has been met. Measurement

range can be selected by register command.

1.2.3

Factory calibration

Sensors are factory calibrated. Trimmed parameters are gain, offset, internal current reference and

frequency of the internal oscillator. Calibration parameters will be read automatically from the

internal non-volatile memory during sensor startup.