ANALOG DEVICES ADXL212 Service Manual

Precision ±2 g Dual Axis,

V

C

FEATURES

Dual axis accelerometer on a single IC chip
5 mm × 5 mm × 2 mm LCC package
5 mg resolution at 60 Hz
Low power: 700 μA at V
High zero g bias stability
High sensitivity accuracy
Pulse width modulated digital outputs
X- and Y-axis aligned to within 0.1° (typical)
Bandwidth adjustment with a single capacitor
Single-supply operation
3500 g shock survival

APPLICATIONS

Automotive tilt alarms
Vehicle dynamic control (VDC)/electronic stability program

(ESP) systems
Electronic chassis control
Electronic braking
Data projectors
Navigation
Platform stabilization/leveling
Alarms and motion detectors
High accuracy, 2-axis tilt sensing

= 5 V (typical)

S

PWM Output Accelerometer

ADXL212

GENERAL DESCRIPTION

The ADXL212 is a high precision, low power, complete dual
axis accelerometer with signal conditioned, duty cycle modulated
outputs, all on a single monolithic IC. The ADXL212 measures
acceleration with a full-scale range of ±2 g (typical). The ADXL212
measures both dynamic acceleration (such as vibration) and
static acceleration (such as gravity).

The outputs are digital signals whose duty cycles (ratio of pulse
width to period) are proportional to acceleration (12.5%/g) in
each of the two sensitive axes. The duty cycle outputs can be
directly measured by a microcontroller without an analog-to­digital converter (ADC) or glue logic. The output period is
adjustable from 0.5 ms to 10 ms via a single resistor (R

The typical noise floor is 500 µg/√Hz, allowing signals below
5 mg (0.3° of inclination) to be resolved in tilt sensing applica­tions using narrow bandwidths (<60 Hz).

The user selects the bandwidth of the accelerometer using
Capacitors C

and CY at the X

X

FILT

and Y

pins. Bandwidths

FILT

of 0.5 Hz to 500 Hz can be selected to suit the application.
The ADXL212 is available in a 5 mm × 5 mm × 2 mm, 8-lead

hermetic LCC package.

SET

).

FUNCTIONAL BLOCK DIAGRAM

+

S

V

S

ADXL212

DC

SENSOR

COM ST X

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.

AC

AMP

DEMOD

Figure 1.

C

Y

Y

FILT

32kΩ

OUTPUT

AMP

OUTPUT

AMP

32kΩ

PWM OUTPUT WAVEFORM SAMPLE

t1

A(g) = (t1/ t2 – 0.5)/12.5%
0g = 50% DUTY CYCLE
t2(sec) = R

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: [phone] www.analog.com
Fax: [phone] ©2011 Analog Devices, Inc. All rights reserved.

FILT

C

DCM

X

t2

/125MΩ

SET

Y

OUT

X

OUT

T2

R

SET

09804-001

ADXL212

TABLE OF CONTENTS

Features.............................................................................................. 1

Applications....................................................................................... 1

General Description......................................................................... 1

Functional Block Diagram ..............................................................1

Revision History ...............................................................................2

Specifications..................................................................................... 3

Absolute Maximum Ratings............................................................ 4

Thermal Resistance...................................................................... 4

ESD Caution.................................................................................. 4

Pin Configuration and Function Descriptions............................. 5

Typical Performance Characteristics............................................. 6

Theory of Operation ........................................................................ 9

Performance.................................................................................. 9

REVISION HISTORY

5/11—Revision 0: Initial Version

Applications Information.............................................................. 10

Power Supply Decoupling......................................................... 10

Setting the Bandwidth Using CX and CY................................. 10

Self Test........................................................................................ 10

Design Trade-Offs for Selecting Filter Characteristics: Noise

vs. Bandwidth ............................................................................. 10

Using the ADXL212 with Operating Voltages Other Than 5 V

....................................................................................................... 11

Using the ADXL212 as a Dual Axis Tilt Sensor..................... 11

Outline Dimensions....................................................................... 12

Ordering Guide .......................................................................... 12

Rev. 0 | Page 2 of 12

ADXL212

SPECIFICATIONS

TA = –40°C to +85°C, VS = 5 V, CX = CY = 0.1 F, acceleration = 0 g, unless otherwise noted. All minimum and maximum specifications
are guaranteed. Typical specifications are not guaranteed.

Table 1.

Parameter Test Conditions/Comments Min Typ Max Unit

SENSOR INPUT Each axis

Measurement Range1 ±1.5 ±2
Nonlinearity Best fit straight line ±0.2 % of FS
Package Alignment Error ±1 Degrees
Alignment Error X sensor to Y sensor ±0.01 Degrees
Cross Axis Sensitivity ±2 %

SENSITIVITY (RATIOMETRIC)2 Each axis

Sensitivity at X
Sensitivity Change Due to Temperature3 V

, Y

V

OUT

OUT

= 5 V 10 12.5 15 %/g

S

= 5 V ±0.5 %

S

ZERO g BIAS LEVEL (RATIOMETRIC) Each axis

0 g Duty Cycle at X

, Y

25 50 75 %

OUT

OUT

Initial 0 g Output Deviation from Ideal TA = 25°C ±2 %
0 g Duty Cycle vs. Supply 1.0 4.0 %/V
0 g Offset vs. Temperature ±2 mg/°C

NOISE PERFORMANCE

Noise Density TA = 25°C 500 1000 μg/√Hz rms

FREQUENCY RESPONSE4

3 dB Bandwidth5 500 Hz
CX, CY Range5 0.002 4.7 μF
Sensor Resonant Frequency 5.5 kHz

SELF TEST6

Duty Cycle Change Self test (ST) pin: pulled low (0) to high (1) 10 %

DUTY CYCLE OUTPUT STAGE

7

f

R

SET

7

f

Tol erance R

SET

= 125 kΩ 1 kHz

SET

= 125 kΩ 0.7 1.3 kHz

SET

Voltage Levels

High I = 25 μA VS − 0.2 V

Low I = 25 μA 200 mV
t2 Drift vs. Temperature ±35 ppm/°C
Rise/Fall Time 200 ns

POWER SUPPLY

Operating Voltage Range 3.0 5.25 V
Specified Performance 4.75 5.25 V
Quiescent Supply Current 0.7 1.1 mA
Turn-On Time8 19 ms

TEMPERATURE RANGE

Specified Performance −40 +85 °C

1

Guaranteed by measurement of initial offset and sensitivity.

2

Sensitivity varies with VS. At VS = 3 V, sensitivity is typically 7.5%/g.

3

Defined as the output change from ambient-to-maximum temperature or ambient-to-minimum temperature.

4

Actual frequency response is controlled by a user supplied external capacitor (CX, CY).

5

Bandwidth = 1/(2 × π × 32 kΩ × C). For CX, CY = 0.002 μF, bandwidth = 2500 Hz. For CX, CY = 4.7 μF, bandwidth = 1 Hz. Minimum/maximum values are not tested.

6

Self test response changes with VS. At VS = 3 V, self test output is typically 6%.

7

The value of f

f

SET

8

Larger values of CX, CY increase turn-on time. Turn-on time is approximately 160 × CX or CY + 3, where CX, CY are in μF, and the resulting turn-on time is in ms.

is defined by the following equation:

SET

1

=

t2

g

Rev. 0 | Page 3 of 12

ADXL212

A

A

ABSOLUTE MAXIMUM RATINGS

Table 2.

Parameter Rating

Acceleration (Any Axis, Unpowered) 1000 g
Acceleration (Any Axis, Powered) 1000 g
VS −0.3 V to +7.0 V
Output Short-Circuit Duration

Indefinite

(Any Pin to Common)
Operating Temperature Range −55°C to +125°C
Storage Temperature Range −65°C to +150°C

Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.

T

T

TURE

TEMPER

P

L

T

SMAX

T

SMIN

PREHEAT

RAMP-UP

t

S

THERMAL RESISTANCE

θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.

Table 3. Thermal Resistance

Package Type θJA θ

8-Lead Ceramic LCC 120°C/W 20°C/W <1.0 g

ESD CAUTION

t

P

t

L

RAMP-DOWN

CRITIC

T

L

TO T

LZONE

P

Device Weight

JC

t

25°C TO PEAK

Figure 2. Recommended Soldering Profile

TIME

09804-002

Table 4. Soldering Profile

Condition

Profile Feature

Sn63/Pb37 Pb Free

Average Ramp Rate (TL to TP) 3°C/sec maximum
Preheat

Minimum Temperature (T

Minimum Temperature (T

Time (T
T

to TL

SMAX

SMIN

to T

) (tS) 60 sec to 120 sec 60 sec to 150 sec

SMAX

) 100°C 150°C

SMIN

) 150°C 200°C

SMAX

Ramp-Up Rate 3°C/sec maximum

Time (tL) Maintained Above Liquidous (TL)

Liquidous Temperature (TL) 183°C 217°C

Time (tL) 60 sec to 150 sec 60 sec to 150 sec
Peak Temperature (TP) 240°C +0°C/–5°C 260°C +0°C/–5°C
Time Within 5°C of Actual Peak Temperature (tP) 10 sec to 30 sec 20 sec to 40 sec
Ramp-Down Rate 6°C/sec maximum
Time 25°C to Peak Temperature 6 minutes maximum 8 minutes maximum

Rev. 0 | Page 4 of 12