MMA1213EGR2 - Freescale Semiconductor

MOTOROLA

SEMICONDUCTOR TECHNICAL DATA Order Number: MMA1213D

Rev. 0, 06/2004

REV 0

Surface Mount

Micromachined Accelerometer

The MMA series of silicon capacitive, micromachined accelerometers features

signal conditioning, a 4-pole low pass filter and temperature compensation. Zero-g

offset full scale span and filter cut-off are factory set and require no external devices.

A full system self-test capability verifies system functionality.

Features

• Integral Signal Conditioning

• Linear Output

• Ratiometric Performance

• 4th Order Bessel Filter Preserves Pulse Shape Integrity

• Calibrated Self-test

• Low Voltage Detect, Clock Monitor, and EPROM Parity Check Status

• Transducer Hermetically Sealed at Wafer Level for Superior Reliability

• Robust Design, High Shocks Survivability

Typical Applications

• Vibration Monitoring and Recording

• Impact Monitoring

ORDERING INFORMATION

Figure 1. Simplified Accelerometer Functional Block Diagram

Device Temperature

Range

Package

MMA1213D – 40 to +125°C SOIC-16

MMA1213DR2 – 40 to +125°C SOIC-16, Tape & Reel

MMA1213D

16 LEAD SOIC

CASE 475–01

PIN ASSIGNMENT

MMA1213D: Z AXIS SENSITIVITY

MICROMACHINED

ACCELEROMETER

±50g

N/C

VOUT

STATUS

VSS

VDD

N/C

G-Cell

Sensor Integrator Gain Filter Temp

Comp

Self-test

Control Logic &

EPROM

Trim Circuits

Clock

Gen.

Oscillator

VDD

VOUT

VSS

Status

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MMA1213D Motorola Sensor Device Data

Maximum Ratings

(Maximum ratings are the limits to which the device can be exposed without causing permanent damage.)

NOTES:

1. Dropped onto concrete surface from any axis.

ELECTRO STATIC DISCHARGE (ESD)

WARNING: This device is sensitive to electrostatic

discharge.

Although the Motorola accelerometers contain internal 2kV

ESD protection circuitry, extra precaution must be taken by the

user to protect the chip from ESD. A charge of over 2000 volts

can accumulate on the human body or associated test

equipment. A charge of this magnitude can alter the

performance or cause failure of the chip. When handling the

accelerometer, proper ESD precautions should be followed to

avoid exposing the device to discharges which may be

detrimental to its performance.

Rating Symbol Value Unit

Powered Acceleration (all axes) Gpd 1500 g

Unpowered Acceleration (all axes) Gupd 2000 g

Supply Voltage VDD –0.3 to +7.0 V

Drop Test (1) Ddrop 1.2 m

Storage Temperature Range Tstg –40 to +125 °C

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Motorola Sensor Device Data MMA1213D

Operating Characteristics

(Unless otherwise noted: –40°C ≤ TA ≤ +105°C, 4.75 ≤ VDD ≤ 5.25, Acceleration = 0g, Loaded output.(1))

NOTES:

1. For a loaded output the measurements are observed after an RC filter consisting of a 1 kΩ resistor and a 0.01 µF capacitor to ground.

2. These limits define the range of operation for which the part will meet specification.

3. Within the supply range of 4.75 and 5.25 volts, the device operates as a fully calibrated linear accelerometer. Beyond these supply limits the

device may operate as a linear device but is not guaranteed to be in calibration.

4. The device can measure both + and – acceleration. With no input acceleration the output is at midsupply. For positive acceleration the output

will increase above VDD/2 and for negative acceleration the output will decrease below VDD/2.

5. The device is calibrated at 20g.

6. At clock frequency ≅70 kHz.

7. The digital input pin has an internal pull-down current source to prevent inadvertent self test initiation due to external board level leakages.

8. Time for the output to reach 90% of its final value after a self-test is initiated.

9. Time for amplifiers to recover after an acceleration signal causing them to saturate.

10. Preserves phase margin (60°) to guarantee output amplifier stability.

11. A measure of the device's ability to reject an acceleration applied 90° from the true axis of sensitivity.

12. The Status pin output is not valid following power-up until at least one rising edge has been applied to the self-test pin. The Status pin is high

whenever the self-test input is high, as a means to check the connectivity of the self-test and Status pins in the application.

13. The Status pin output latches high if a Low Voltage Detection or Clock Frequency failure occurs, or the EPROM parity changes to odd. The

Status pin can be reset low if the self-test pin is pulsed with a high input for at least 100 µs, unless a fault condition continues to exist.

Characteristic Symbol Min Typ Max Unit

Operating Range (2)

Supply Voltage (3)

Supply Current

Operating Temperature Range

Acceleration Range

VDD

IDD

gFS

4.75

3.0

–40

—

5.00

—

56.3

5.25

6.0

+125

—

°C

Output Signal

Zero g (TA = 25°C, VDD = 5.0 V)(4)

Zero g

Sensitivity (TA = 25°C, VDD = 5.0 V)(5)

Sensitivity

Bandwidth Response

Nonlinearity

VOFF

VOFF,V

f–3dB

NLOUT

2.35

0.46 VDD

7.44

360

–1.0

2.5

0.50 VDD

400

—

2.65

0.54 VDD

8.56

440

1.0

mV/g

mV/g/V

% FSO

Noise

RMS (0.1-1 kHz)

Power Spectral Density

Clock Noise (without RC load on output)(6)

nRMS

nPSD

nCLK

—

110

2.0

2.8

—

mVrms

µV/(Hz1/2)

mVpk

Self-Test

Output Response

Input Low

Input High

Input Loading(7)

Response Time(8)

gST

VIL

VIH

IIN

tST

VSS

0.7 × VDD

–30

—

–100

2.0

0.3 × VDD

VDD

–260

µA

Status(12)(13)

Output Low (Iload = 100 µA)

Output High (Iload = 100 µA)

VOL

VOH

—

VDD –.8

—

0.4

—

Minimum Supply Voltage (LVD Trip) VLVD 2.7 3.25 4.0 V

Clock Monitor Fail Detection Frequency fmin 50 —260 kHz

Output Stage Performance

Electrical Saturation Recovery Time(9)

Full Scale Output Range (IOUT = 200 µA)

Capacitive Load Drive(10)

Output Impedence

tDELAY

VFSO

—

–0.25

—

0.2

—

300

—

VDD –0.25

100

—

Ω

Mechanical Characteristics

Transverse Sensitivity(11)

Package Resonance

VXZ,YZ

fPKG

—

5.0

—

% FSO

kHz

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MMA1213D Motorola Sensor Device Data

PRINCIPLE OF OPERATION

The Motorola accelerometer is a surface-micromachined

integrated-circuit accelerometer.

The device consists of a surface micromachined capacitive

sensing cell (g-cell) and a CMOS signal conditioning ASIC

contained in a single integrated circuit package. The sensing

element is sealed hermetically at the wafer level using a bulk

micromachined “cap'' wafer.

The g-cell is a mechanical structure formed from

semiconductor materials (polysilicon) using semiconductor

processes (masking and etching). It can be modeled as two

stationary plates with a moveable plate in-between. The center

plate can be deflected from its rest position by subjecting the

system to an acceleration (Figure 2).

When the center plate deflects, the distance from it to one

fixed plate will increase by the same amount that the distance

to the other plate decreases. The change in distance is a

measure of acceleration.

The g-cell plates form two back-to-back capacitors

(Figure 3). As the center plate moves with acceleration, the

distance between the plates changes and each capacitor's

value will change, (C = Aε/D). Where A is the area of the plate,

ε is the dielectric constant, and D is the distance between the

plates.

The CMOS ASIC uses switched capacitor techniques to

measure the g-cell capacitors and extract the acceleration data

from the difference between the two capacitors. The ASIC also

signal conditions and filters (switched capacitor) the signal,

providing a high level output voltage that is ratiometric and

proportional to acceleration.

SPECIAL FEATURES

Filtering

The Motorola accelerometers contain an onboard 4-pole

switched capacitor filter. A Bessel implementation is used

because it provides a maximally flat delay response (linear

phase) thus preserving pulse shape integrity. Because the filter

is realized using switched capacitor techniques, there is no

requirement for external passive components (resistors and

capacitors) to set the cut-off frequency.

Self-Test

The sensor provides a self-test feature that allows the

verification of the mechanical and electrical integrity of the

accelerometer at any time before or after installation. This

feature is critical in applications such as automotive airbag

systems where system integrity must be ensured over the life of

the vehicle. A fourth “plate'' is used in the g-cell as a self-test

plate. When the user applies a logic high input to the self-test

pin, a calibrated potential is applied across the self-test plate

and the moveable plate. The resulting electrostatic force

(Fe = 1/2AV2/d2) causes the center plate to deflect. The

resultant deflection is measured by the accelerometer's control

ASIC and a proportional output voltage results. This procedure

assures that both the mechanical (g-cell) and electronic

sections of the accelerometer are functioning.

Ratiometricity

Ratiometricity simply means that the output offset voltage

and sensitivity will scale linearly with applied supply voltage.

That is, as you increase supply voltage the sensitivity and offset

increase linearly; as supply voltage decreases, offset and

sensitivity decrease linearly. This is a key feature when

interfacing to a microcontroller or an A/D converter because it

provides system level cancellation of supply induced errors in

the analog to digital conversion process.

Status

Motorola accelerometers include fault detection circuitry and

a fault latch. The Status pin is an output from the fault latch,

OR'd with self-test, and is set high whenever one (or more) of

the following events occur:

• Supply voltage falls below the Low Voltage Detect (LVD)

voltage threshold

• Clock oscillator falls below the clock monitor

minimum frequency

• Parity of the EPROM bits becomes odd in

number.

The fault latch can be reset by a rising edge on the self-test

input pin, unless one (or more) of the fault conditions continues

to exist.

Acceleration

Figure 2. Transducer

Physical Model

Figure 3. Equivalent

Circuit Model

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Motorola Sensor Device Data MMA1213D

BASIC CONNECTIONS

Pinout Description

Figure 4. Accelerometer with Recommended

Connection Diagram

Figure 5. Recommended PCB Layout for Interfacing

Accelerometer to Microcontroller

NOTES:

• Use a 0.1 µF capacitor on VDD to decouple the power

source.

• Physical coupling distance of the accelerometer to the

microcontroller should be minimal.

• Place a ground plane beneath the accelerometer to reduce

noise, the ground plane should be attached to all of the open

ended terminals shown in Figure 5.

• Use an RC filter of 1 kΩ and 0.01 µF on the output of the

accelerometer to minimize clock noise (from the switched

capacitor filter circuit).

• PCB layout of power and ground should not couple power

supply noise.

• Accelerometer and microcontroller should not be a high

current path.

• A/D sampling rate and any external power supply switching

frequency should be selected such that they do not interfere

with the internal accelerometer sampling frequency. This

will prevent aliasing errors.

Pin No. Pin Name Description

1 thru 3 — Leave unconnected.

4ST

Logic input pin used to initiate

self-test.

OUT

Output voltage of the

accelerometer.

6STATUS

Logic output pin to indicate

fault.

SS The power supply ground.

DD The power supply input.

9 thru 13 Trim pins Used for factory trim. Leave

unconnected.

14 thru 16 — No internal connection. Leave

unconnected.

N/C

VOUT

STATUS

VSS

VDD

N/C

MMA1213D

VOUT Output

Signal

1 kΩ

0.01 µF

Logic

Input

VDD

0.1 µF

Status

8VDD

VSS

A/D In

VRH

VSS

VDD

VOUT

VSS

VDD

0.01 µF1 kΩ

0.1 µF

Power Supply

0.1 µF

P1Status

Micorocontroller

Accelerometer

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MMA1213D Motorola Sensor Device Data

Acceleration of the package in the

+Z direction (center plate moves

in the −Z direction) will result in an

increase in the output.

* When positioned as shown, the Earth's gravity will result in a positive 1g output.

Dynamic Acceleration Sensing Direction

Direction of Earth's gravity field.*

−Z

Side View

Static Acceleration Sensing Direction

Activation of Self test moves

the center plate in the −Z

direction, resulting in an

increase in the output.

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Motorola Sensor Device Data MMA1213D

PACKAGE DIMENSIONS

MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICATIONS

Surface mount board layout is a critical portion of the total

design. The footprint for the surface mount packages must be

the correct size to ensure proper solder connection interface

between the board and the package. With the correct footprint,

the packages will self-align when subjected to a solder reflow

process. It is always recommended to design boards with a

solder mask layer to avoid bridging and shorting between solder

pads.

Figure 6. Footprint SOIC-16 (Case 475-01)

SEATING

PLANE

0.1

CASE 475-01

ISSUE B

16 9

2 PLACES, 16 TIPS

16X

A0.15 BT

0.13 BT

G/2

NOTES:

1. ALL DIMENSIONS ARE IN MILLIMETERS.

2. INTERPRET DIMENSIONS AND TOLERANCES

PER ASME Y14.5M, 1994.

3. DIMENSIONS "A" AND "B" DO NOT INCLUDE

MOLD FLASH OR PROTRUSIONS. MOLD FLASH

OR PROTRUSIONS SHALL NOT EXCEED 0.15

PER SIDE.

4. DIMENSION "D" DOES NOT INCLUDE DAMBAR

PROTRUSION. PROTRUSIONS SHALL NOT

CAUSE THE LEAD WIDTH TO EXCEED 0.75

DIM MIN MAX

MILLIMETERS

A10.15 10.45

B7.40 7.60

C3.30 3.55

D0.35 0.49

F0.76 1.14

G1.27 BSC

J0.25 0.32

K0.10 0.25

M0˚ 7˚

P10.16 10.67

R0.25 0.75

RX 45˚

CASE 475-01

ISSUE B

16 LEAD SOIC

0.380 in.

9.65 mm

0.050 in.

1.27 mm

0.024 in.

0.610 mm

0.080 in.

2.03 mm

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HOW TO REACH US:

USA/EUROPE/LOCATIONS NOT LISTED:JAPAN: Motorola Japan Ltd.; SPS, Technical Information Center

Motorola Literature Distribution 3-20-1 Minami-Azabu. Minato-ku, Tokyo 106-8573, Japan

P.O. Box 5405, Denver, Colorado 80217 81-3-3440-3569

1-800-521-6274 or 480-768-2130

ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; Silicon Harbour Centre

2 Dai King Street, Tai Po Industrial Estate, Tai Po, N.T., Hong Kong

852-26668334

HOME PAGE: http://motorola.com/semiconductors

MMA1213D

Information in this document is provided solely to enable system and software implementers to use Motorola products. There are no express or implied

copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document.

Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee

regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product

or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be

provided in Motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating

parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. Motorola does not convey any license

under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for

surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product

could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or

unauthorized application, Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all

claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated

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MOTOROLA and the Stylized M Logo are registered in the US Patent and Trademark Office. All other product or service names are the property of their

respective owners.

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