CMA3000-D0X Series
1
1.1
General Description
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.
C/V
Analog
calibration
&
ADC
DE-
MUX
1:3
Low-pass
Filter
Low-pass
Filter
Low-pass
Filter
SCK/SCL
SPI
&
I2C
i/f
MISO
MOSI/SDA
CSB
Oscillator
&
clock
Reference
Non-
Volatile
Memory
Motion
detector
Free fall
detector
Control
&
INT
INT
Figure 1. CMA3000-D0X block diagram with digital SPI and I
2
C interface
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
1.2.1
Functional Description
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
2
C interface.
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.
VTI Technologies Oy
www.vti.fi
Doc.Nr. 8281000.12
5/ 35
Rev. 0.12
VTI [ VTI TECHNOLOGIES ]
