|
|
PDF ADXL210E Data sheet ( Hoja de datos )
| Número de pieza | ADXL210E | |
| Descripción | Low-Cost 10 g Dual-Axis Accelerometer | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de ADXL210E (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
|
No Preview Available !
a
FEATURES
2-Axis Acceleration Sensor on a Single IC Chip
5 mm ؋ 5 mm ؋ 2 mm Ultrasmall Chip Scale Package
2 mg Resolution at 60 Hz
Low Power < 0.6 mA
Direct Interface to Low-Cost Microcontrollers via
Duty Cycle Output
BW Adjustment with a Single Capacitor
www.DataSheet4U3.cVomto 5.25 V Single-Supply Operation
1000 g Shock Survival
APPLICATIONS
2-Axis Tilt Sensing with Faster Response than
Electrolytic, Mercury, or Thermal Sensors
Computer Peripherals
Information Appliances
Alarms and Motion Detectors
Disk Drives
Vehicle Security
Low-Cost ؎10 g Dual-Axis
Accelerometer with Duty Cycle
ADXL210E
FUNCTIONAL BLOCK DIAGRAM
3V TO 5.25V
VDD
CX
XFILT
SELF-TEST
X SENSOR
DEMOD
RFILT
32k⍀
ANALOG
XOUT
C
O
CDC
OSCILLATOR
ADXL210E
TO
DUTY
U
N P
CYCLE
T
DEMOD
Y SENSOR
RFILT
32k⍀
(ADC)
YOUT
E
R
COM
YFILT
T2
CY RSET
T2
T1
A(g) = (T1/T2 – 0.5)/4%
0g = 50% DUTY CYCLE
T2 = RSET/125M⍀
GENERAL DESCRIPTION
The ADXL210E is a low-cost, low-power, complete 2-axis acceler-
ometer with a digital output, all on a single monolithic IC. It is an
improved version of the ADXL210AQC/JQC. The ADXL210E
will measure accelerations with a full-scale range of ± 10 g. The
ADXL210E can measure both dynamic acceleration (e.g., vibra-
tion) and static acceleration (e.g., gravity).
The outputs are analog voltage or digital signals whose duty cycles
(ratio of pulsewidth to period) are proportional to acceleration.
The duty cycle outputs can be directly measured by a micro-
processor counter without an A/D converter or glue logic. The
duty cycle period is adjustable from 0.5 ms to 10 ms via a single
resistor (RSET).
The typical noise floor is 200 g√Hz, allowing signals below
2 mg (at 60 Hz bandwidth) to be resolved.
The bandwidth of the accelerometer is set with capacitors CX and
CY at the XFILT and YFILT pins. An analog output can be recon-
structed by filtering the duty cycle output.
The ADXL210E is available in a 5 mm ϫ 5 mm ϫ 2 mm 8-lead
hermetic LCC package.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2002
1 page  
VDD = 3 V
35
30
25
20
15
10
www.DataSheet4U.com
5
0
52.5 53.3 54.2 55.0 55.8 56.7 57.5 58.3 59.2 60.0
mV/g
TPC 7. Y-Axis Sensitivity Distribution at YFILT, VDD = 3 V
ADXL210E
VDD = 3 V
70
60
50
40
30
20
10
0
95.0
97.5 100.0 103.0 105.0 108.0 110.0 113.0
mV/g
TPC 10. Y-Axis Sensitivity Distribution at YFILT, VDD = 5 V
70
60
50
40
30
20
10
0
3.5
3.6 3.7 3.8 3.9 4.0
PERCENT DUTY CYCLE PER g
4.1
TPC 8. X-Axis Sensitivity Distribution at XOUT, VDD = 3 V
70
60
50
40
30
20
10
0
3.9
4.0 4.1 4.2 4.3
PERCENT DUTY CYCLE PER g
4.4
TPC 11. X-Axis Sensitivity Distribution at XOUT, VDD = 5 V
70
60
50
40
30
20
10
0
3.4
3.5 3.6 3.7 3.8 3.9 4.0
PERCENT DUTY CYCLE PER g
4.1
TPC 9. Y-Axis Sensitivity Distribution at YOUT, VDD = 3 V
70
60
50
40
30
20
10
0
3.8
3.9 4.0 4.1 4.2 4.3
PERCENT DUTY CYCLE PER g
4.4
TPC 12. Y-Axis Sensitivity Distribution at YOUT, VDD = 5 V
REV. 0
–5–
5 Page 
ADXL210E
Table V. Trade-Offs Between Microcontroller Counter Rate,
T2 Period, and Resolution of Duty Cycle Modulator
Counter-
ADXL210E Clock Counts
RSET Sample
T2 (ms) (k⍀) Rate
Rate per T2
(MHz) Cycle
Counts Resolution
per g (mg)
1.0 124 1000
1.0 124 1000
1.0 124 1000
5.0 625 200
5.0 625 200
5.0 625 200
10.0 1250 100
www.DataShee1t40U.0.com 1250 100
10.0 1250 100
2.0
2000 80
12.50
1.0
1000 40
25.00
0.5 500 20 50.00
2.0 10000 400 2.50
1.0 5000 200 5.00
0.5 2500 100 10.00
2.0 20000 800 1.25
1.0 10000 400 2.50
0.5 5000 200 5.00
USING THE ANALOG OUTPUT
The ADXL210E was specifically designed for use with its digital
outputs, but has provisions to provide analog outputs as well.
Duty Cycle Filtering
An analog output can be reconstructed by filtering the duty cycle
output. This technique requires only passive components. The
duty cycle period (T2) should be set to <1 ms. An RC filter with a
3 dB point at least a factor of >10 less than the duty cycle fre-
quency is connected to the duty cycle output. The filter resistor
should be no less than 100 kΩ to prevent loading of the output
stage. The analog output signal will be ratiometric to the supply
voltage. The advantage of this method is an output scale factor of
approximately double the analog output. Its disadvantage is that
the frequency response will be lower than when using the XFILT,
YFILT output.
XFILT, YFILT Output
The second method is to use the analog output present at the
XFILT and YFILT pin. Unfortunately, these pins have a 32 kΩ
output impedance and are not designed to drive a load directly.
An op amp follower may be required to buffer this pin. The
advantage of this method is that the full 5 kHz bandwidth of the
accelerometer is available to the user. A capacitor still must be
added at this point for filtering. The duty cycle converter should
be kept running by using RSET <10 MΩ. Note that the acceler-
ometer offset and sensitivity are ratiometric to the supply voltage.
The offset and sensitivity are nominally:
0 g Offset = VDD/2
ADXL210E Sensitivity = (20 mV ϫ VS)/g
USING THE ADXL210E IN VERY LOW POWER
APPLICATIONS
An application note outlining low power strategies for the
ADXL210E is available. Some key points are presented here.
It is possible to reduce the ADXL210E’s average current from
0.6 mA to less than 20 µA by using the following techniques:
1. Power cycle the accelerometer.
2. Run the accelerometer at a lower voltage (down to 3 V).
Power Cycling with an External A/D
Depending on the value of the XFILT capacitor, the ADXL210E
is capable of turning on and giving a good reading in 1.6 ms.
Most microcontroller-based A/Ds can acquire a reading in
another 25 µs. Thus it is possible to turn on the ADXL210E
and take a reading in <2 ms. If we assume that a 20 Hz sample
rate is sufficient, the total current required to take 20 samples is:
2 ms ϫ 20 Samples/s ϫ 0.6 mA = 24 µA
Running the part at 3 V will reduce the supply current from
0.6 mA to 0.4 mA, bringing the average current down to 16 µA.
The A/D should read the analog output of the ADXL210E at
the XFILT and YFILT pins. A buffer amplifier is recommended, and
may be required in any case to amplify the analog output to give
enough resolution with an 8-bit to 10-bit converter.
Power Cycling When Using the Digital Output
An alternative is to run the microcontroller at a higher clock rate
and put it into shutdown between readings, allowing the use of the
digital output. In this approach the ADXL210E should be set at
its fastest sample rate (T2 = 0.5 ms), with a 500 Hz filter at XFILT
and YFILT. The concept is to acquire a reading as quickly as
possible and then shut down the ADXL210E and the microcon-
troller until the next sample is needed.
In either of the above approaches, the ADXL210E can be turned
on and off directly using a digital port pin on the microcontroller to
power the accelerometer without additional components.
CALIBRATING THE ADXL210E
The initial value of the offset and scale factor for the ADXL210E will
require calibration for applications such as tilt measurement. The
ADXL210E architecture has been designed so that these calibra-
tions take place in the software of the microcontroller used to decode
the duty cycle signal. Calibration factors can be stored in EEPROM
or determined at turn-on and saved in dynamic memory.
For low g applications, the force of gravity is the most stable,
accurate and convenient acceleration reference available. A reading
of the 0 g point can be determined by orientating the device
parallel to the earth’s surface and then reading the output.
A more accurate calibration method is to make measurements at
+1 g and –1 g. The sensitivity can be determined by the two
measurements.
To calibrate, the accelerometer’s measurement axis is pointed
directly at the earth. The 1 g reading is saved and the sensor is
turned 180° to measure –1 g. Using the two readings, the sensi-
tivity is:
Let A = Accelerometer output with axis oriented to +1 g
Let B = Accelerometer output with axis oriented to –1 g then:
Sensitivity = [A – B]/2 g
For example, if the +1 g reading (A) is 55% duty cycle and the
–1 g reading (B) is 47% duty cycle, then:
Sensitivity = [55% – 47%]/2 g = 4%/g
These equations apply whether the output is analog or duty cycle.
Application notes outlining algorithms for calculating accelera-
tion from duty cycle and automated calibration routines are
available from the factory.
REV. 0
–11–
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet ADXL210E.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| ADXL210 | Low Cost +-2 g/+-10 g Dual Axis iMEMS Accelerometers with Digital Output | Analog Devices |
| ADXL210E | Low-Cost 10 g Dual-Axis Accelerometer | Analog Devices |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |