MMA3202D - Freescale Semiconductor / Motorola

MOTOROLA

SEMICONDUCTOR TECHNICAL DATA

REV 1

Order number: MMA3202 D

Rev 1, 1/2004

Surface Mount

Micromachined Ac celerometer

The MMA3200 series of dual axis (X and Y) silicon capacitive, micro-

machined accelerometers features signal conditioning, a 4-pole low

pass filter , temperature compensation and separate outputs for the two

axes. 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

• Sensitivity in two separate axes: 100g X-axis and 50g Y-axis

• 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

• Appliance Control

• Mechanical Bearing Monitoring

• Computer Hard Drive Protection

• Computer Mouse and Joysticks

• Virtual Reality Input Devices

• Sport Diagnostic Devices and Systems

ORDERING INFORMATION

Device Temper at ur e Ran ge Case No. Packa ge

MMA3202D – 40 to +125°C Case 475A-01 SOIC-20

MMA3202D: X-Y AXIS SENSITIVITY

MICROMACHINED

ACCELEROMETER

±100/50g

20 LEAD SOIC

CASE 475A-01

MMA3202D

N/C

XOUT

STATUS

VDD

GND

N/C

911

VSS

AVDD

N/C

YOUT

N/C

PIN ASSIGNMENT

Figure 1. Simplified Accelerometer Functional Block Diagram

G-CELL

SENSOR INTEGRATOR GAIN FILTER TEMP

COMP

SELF-TEST CONTROL LOGIC &

EPROM TRIM

CIRCUITS CLOCK GEN.

OSCILLATOR

VDD

XOUT

VSS

STATUS

AVDD

YOUT

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2 Surface Mount Micromachined Accelerometer MOTOROLA

MMA3202D

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 precau-

tions should be followed to avoid exposing the device to

discharges which may be detrimental to its performance.

Rating Symbol Value Unit

Powe red A c celeration (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 Surface Mount Micromachined Accelerometer 3

MMA3202D

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 ca pacitor to grou n d.

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

3. Within th e su pply r ang e o f 4. 75 a nd 5.25 volt s, the dev ice ope rates as a ful ly calib rat ed linear a c celero meter. Beyond t hese suppl y limits the dev ice may

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

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

increas e above VDD/2 and for nega tiv e 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 sourc e to prevent inad vertent self te st initiation due to external board level leakage s.

8. Time for the ou tput to reach 90% of i ts final value after a self-test is initiated.

9. Time for amplifiers to recover after an acceleratio n signal causing them to satura te.

10. Preserves pha se margin (60°) to guarantee ou tpu t amplifier stabilit y.

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-te st pin. The Status pin is high whenever

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

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

can be reset low if the self-te st 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 V oltag e (3)

Supply C urrent

Operating Temperature Range

Acceleration Range X-axis

Acceleration Range Y-axis

VDD

IDD

gFS

4.75

−40

—

5.00

—

112.5

56.3

5.25

+125

—

°C

Output Signal

Zero g (TA = 25°C, VDD = 5.0 V)(4)

Zero g

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

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

Sensitivity X-axis

Sensitivity Y-axis

Bandwidth Response

Nonlinearity

VOFF

VOFF,v

f–3dB

NLOUT

2.35

0.46VDD

3.72

7.44

360

−1.0

2.5

0.50 VDD

400

—

2.65

0.54 VDD

4.28

8.56

440

+1.0

mV/g

mV/g/V

% FSO

Noise

RMS (.01 Hz – 1 kHz)

Power S pect ral D ensit y

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

9.6

VSS

0.7 x VDD

−30

—

−100

2.0

14.4

0.3 x VDD

VDD

−300

—

µA

Status(12)(13)

Output Low (Iload = 100 µA)

Output High (Iload = 100 µA) VOL

VOH

—

VDD –0.8 —

—0.4

—V

Mini mum Supply Vo ltage (LVD Trip) VLVD 2.7 3.25 4.0 V

Clock Monitor Fail Detection Frequency fmin 50 —260 kHz

Output Stage Performance

Electrica l Satu rat ion 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 —

——

10 5.0

—% FSO

kHz

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4 Surface Mount Micromachined Accelerometer MOTOROLA

MMA3202D

PRINCIPLE OF OPERATION

The Motorola accelerometer is a surface-microma-

chined integrated-circuit accelerometer.

The device consists of a surface micromachined ca-

pacitive sensing cell (g-cell) and a CMOS signal condi-

tioning 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 semi-

condu cto r mater ial s (poly s il icon ) usi ng se mic on duc tor

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

a set of beams att ached to a movable central mass that

move between fixed beams. The movable beams can be

deflected from their rest position by subjecting the sys-

tem to an acceleration (Figure 2).

As the beams attached to the central mass move, the

distance from them to the fixed beams on one side will in-

crease by the same amount that the distance to the fixed

beams on the other side decreases. The change in dis-

tance is a measure of acceleration.

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

(Figure 2). As the central mass moves with acceleration,

the distance between the beams change and each ca-

pacitor's value will change, (C = NAε/D). Where A is the

area of the facing side of the beam, ε is the dielectric con-

stant, D is the distance between the beams, and N is the

number of beams. The X-Y device contains two struc-

tures at right angles to each other.

The CMOS ASIC uses switched capacitor techniques

to measure the g-cell capacitors and extract the acceler-

ation data from the difference between the two capaci -

tors. The ASIC also signal conditions and filters

(switched capacitor) the signal, providing a high level out-

put voltage that is ratiometric and proportional to acceler-

ation.

Figure 1. Simplified Transducer Physical Model

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. Be-

cause the filter is realized using switched capacitor tech-

niques, 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 ap-

plied 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 as-

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

sections of the accelerometer are functioning.

Ratiometricity

Ratiometricity simply means that the output offset volt-

age and sensitivity will scale linearly with applied supply

voltage. That is, as you increase supply voltage the sen-

sitivity and offset increase linearly; as supply voltage de-

creases, 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 cancella-

tion of supply induced errors in the analog to digital con-

version process.

Status

Motorola accelerometers include fault detection cir-

cuitry and a fault latch. The Status pin is an output from

the fault latch, OR'd with self-test, and is set high when-

ever one (or more) of the following events occur:

• Supply voltage falls below the Low Voltage Detect

(LVD) voltage threshold

Acceleration

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MOTOROLA Surface Mount Micromachined Accelerometer 5

MMA3202D

• 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 falling edge on the

self-test input pin, unless one (or more) of the fault con-

ditions continues to exist.

BASIC CONNECTIONS

Figure 3. SOIC Accelerometer with Recommended

Connec tion Diagr am

Figure 4. Recommended PCB Layout for Interfacing

Accelerometer to Microcontroller

NOTES:

• Use a 0.1

F 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 gro un d pla ne shou ld be atta ch ed to all of the o pen

ended terminals shown in Figure 4.

• Use an RC filter of 1 k

Ω

and 0.01

F on th e outpu t of the

acce lerometer to minimize clock noise (from the switched

capacitor filter circuit).

• PC B layou t of pow er and gr ound sh ould not couple p ower su pply

noise.

• Accel erometer and microcontroll er should not be a high

current path.

• A/D sampli ng rate and any extern al power supp ly switch ing

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 — Redundant VSS. Leave

unconnected.

4 — No internal connection. Leave

unconnected.

5 ST Logic input pin used to initiate self-

test.

OUT Output voltage of the accelerometer.

X Direction.

7 STATUS Logic output pin to indicate fault.

SS The power supply ground.

DD The power supply input.

10 AVDD The power supply input (Analog).

11 YOUT Output voltage of the accelerometer.

Y Direction.

12 thru 16 — Used for factory trim. Leave

unconnected.

17 thru 19 — No internal connection. Leave

unconnected.

20 — Ground

N/C

XOUT

STATUS

VDD

GND

N/C

911

VSS

AVDD

N/C

YOUT

N/C

Pinout Description

XOUT

YOUT

MMA3202D

VSS

X OUTPU T

SIGNAL

1 kΩ

0.01

LOGIC

INPUT

VDD

0.1 µF

Y OUTPU T

SIGNAL

0.01

1 kΩ

AVDD

STATUS

VDD

CB Layout

A/D IN

VRH

VSS

VDD

YOUT

VSS

VDD

0.01 µF

1 kΩ

0.1 µF

POWER SUPPLY

R0.1 µF

STATUS

A/D IN

XOUT R0.01 µF

1 kΩ

MICROCONTROLLER

ACCELEROMETER

C0.01 µF

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6 Surface Mount Micromachined Accelerometer MOTOROLA

MMA3202D

−X

N/C

XOUT

STATUS

VDD

GND

N/C

911

VSS

AVDD

N/C

YOUT

N/C

Direction of Earth’s gravity field.*

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

Front View Side View

Top View

Static Acceleration Sensing Direction

Dynamic Acceleration Sensing Direction

Acceleration of the

package in the +X and

+Y direction (center plates

move in the −X and −Y

direction) will result in an

increase X and Y outputs.

20-Pin SOIC Package

N/C pins are recommended to be left FLOATING

−Y

11 12 13 14 15 16 17 18 19 20

10987654321

Activation of Self test moves

the center plate in the −X

direction, resulting in an

increase in the output.

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MOTOROLA Surface Mount Micromachined Accelerometer 7

MMA3202D

PACKAGE DIMENSIONS

MINIMUM RECOMMENDED FOOTPRINT FOR SURFACE MOUNTED APPLICAT IONS

Surface mount board layout is a critical portion of the

total design. The footprint for the surface mount packag-

es must be the correct size to ensure proper solder con-

nection inter face 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.

DATE 02/10/98

CASE 475A-01

ISSUE O

-T-

SEATING

PLANE

110

20 11

-B-

-A-

10 PL

16 PL

0.13 (0.005) B

INCHESMILLIMETERS

1.27 BSC 0.050 BSC

DIM

MIN

12.67

7.40

3.30

0.35

0.76

0.25

0.10

0˚

10.16

0.25

MAX

12.96

7.60

3.55

0.49

1.14

0.32

0.25

7˚

10.67

0.75

MIN

0.499

0.292

0.130

0.014

0.030

0.010

0.004

0˚

0.400

0.010

MAX

0.510

0.299

0.140

0.019

0.045

0.012

0.009

7˚

0.420

0.029

X 45˚

NOTES:

DIMENSIONING AND TOLERANCING PER ANSI

Y14.5M, 1982.

CONTROLLING DIMENSION: MILLIMETER.

DEMENSIONS A AND B DO NOT INCLUDE MOLD

PROTRUSION.

MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER

SIDE.

DIMENSION D DOES NOT INCLUDE DAMBAR

PROTRUSION. ALLOWABLE DAMBAR

PROTRUSION SHALL BE 0.13 (0.005) TOTAL IN

EXCESS OF D DIMENSION AT MAXIMUM

MATERIAL CONDITION.

20 LEAD SOIC

Figure 5. Footprint SOIC-20 (Case 475A-01)

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 /LOCA TIO NS NO T LISTED: JAPAN: Motorola Japan Ltd.; SPS, Technica l 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

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 re serves the ri ght to make c hanges withou t further not ice to any pr oducts herein. Mo torola make s no warranty, repr esentation or gua rante e

regarding the suitability of its products for any particular purpose, nor does Motorola assu me any liability arising out of the ap pli cat io n or use of a ny pro du ct

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 tim e. A ll op erat in g

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 th e rig hts of others. Motoro la produ cts are not de signed, inten ded, or author ized for use as compo nen ts in systems inte nded fo r

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

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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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respective owners.

MMA3202D

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