Zakładka z wyszukiwarką danych komponentów
Selected language     Polish  ▼
Nazwa części
         Szczegóły


ADXL202AE Datasheet(Arkusz danych) 9 Page - Analog Devices

Numer części ADXL202AE
Szczegółowy opis  Low-Cost -2 g Dual-Axis Accelerometer with Duty Cycle Output
Pobierz  12 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Producent  AD [Analog Devices]
Strona internetowa  http://www.analog.com
Logo 

 
 9 page
background image
REV. A
ADXL202E
–9–
Setting the Bandwidth Using CX and CY
The ADXL202E has provisions for bandlimiting the XFILT and
YFILT pins. Capacitors must be added at these pins to implement
low-pass filtering for antialiasing and noise reduction. The equa-
tion for the 3 dB bandwidth is:
F–3 dB
=
1
2
π (32 kΩ) × C(x, y)
()
or, more simply, F–3 dB =
5
µF
C(X,Y )
The tolerance of the internal resistor (RFILT), can vary typically as
much as
±15% of its nominal value of 32 kΩ; so the bandwidth
will vary accordingly. A minimum capacitance of 1000 pF for
C(X, Y) is required in all cases.
Table I. Filter Capacitor Selection, CX and CY
Capacitor
Bandwidth
Value
10 Hz
0.47
µF
50 Hz
0.10
µF
100 Hz
0.05
µF
200 Hz
0.027
µF
500 Hz
0.01
µF
5 kHz
0.001
µF
Setting the DCM Period with RSET
The period of the DCM output is set for both channels by a single
resistor from RSET to ground. The equation for the period is:
T 2
=
RSET (
Ω)
125 M
A 125 k
Ω resistor will set the duty cycle repetition rate to approxi-
mately 1 kHz, or 1 ms. The device is designed to operate at duty
cycle periods between 0.5 ms and 10 ms.
Table II. Resistor Values to Set T2
T2
RSET
1 ms
125 k
2 ms
250 k
5 ms
625 k
10 ms
1.25 M
Note that the RSET should always be included, even if only an
analog output is desired. Use an RSET value between 500 k
and 2 M
Ω when taking the output from X
FILT or YFILT. The RSET
resistor should be place close to the T2 Pin to minimize parasitic
capacitance at this node.
Selecting the Right Accelerometer
For most tilt sensing applications the ADXL202E is the most
appropriate accelerometer. Its higher sensitivity (12.5%/g) allows
the user to use a lower speed counter for PWM decoding while
maintaining high resolution. The ADXL210 should be used in
applications where accelerations of greater than
±2 g are expected.
DESIGN PROCEDURE FOR THE ADXL202E
The design procedure for using the ADXL202E with a duty cycle
output involves selecting a duty cycle period and a filter capacitor.
A proper design will take into account the application requirements
for bandwidth, signal resolution and acquisition time, as discussed
in the following sections.
Decoupling Capacitor CDC
A 0.1
µF capacitor is recommended from V
DD to COM for power
supply decoupling.
ST
The ST pin controls the self-test feature. When this pin is set to
VDD, an electrostatic force is exerted on the beam of the accelerom-
eter. The resulting movement of the beam allows the user to test if
the accelerometer is functional. The typical change in output will
be 10% at the duty cycle outputs (corresponding to 800 mg).
This pin may be left open circuit or connected to common in
normal use.
Duty Cycle Decoding
The ADXL202E’s digital output is a duty cycle modulator.
Acceleration is proportional to the ratio T1/T2. The nominal
output of the ADXL202E is:
0 g = 50% Duty Cycle
Scale factor is 12.5% Duty Cycle Change per g
These nominal values are affected by the initial tolerance of the
device including zero g offset error and sensitivity error.
T2 does not have to be measured for every measurement cycle.
It need only be updated to account for changes due to tempera-
ture, (a relatively slow process). Since the T2 time period is shared
by both X and Y channels, it is necessary only to measure it on
one channel of the ADXL202E. Decoding algorithms for various
microcontrollers have been developed. Consult the appropriate
Application Note.
ANALOG
TO
DUTY
CYCLE
(ADC)
C
O
U
N
T
E
R
P
XOUT
YOUT
DEMOD
DEMOD
RFILT
32k
RFILT
32k
ADXL202E
RSET
T2
CY
YFILT
SELF-TEST
XFILT
CX
OSCILLATOR
COM
Y SENSOR
X SENSOR
3V TO 5.25V
VDD
CDC
T1
T2
A(g) = (T1/T2 – 0.5)/12.5%
0g = 50% DUTY CYCLE
T2 = RSET/125M
Figure 3. Block Diagram




Html Pages

1  2  3  4  5  6  7  8  9  10  11  12 


Datasheet Download



Powiązane numery części

Numer częściSzczegółowy opis komponentówHtml ViewProducent
ADXL210ELow-Cost 10 g Dual-Axis Accelerometer with Duty Cycle 1 2 3 4 5 MoreAnalog Devices
ADXL202Low Cost +-2 g/+-10 g Dual Axis iMEMS Accelerometers with Digital Output 1 2 3 4 5 MoreAnalog Devices
ADXL190Low Cost +-100 gSingle Axis Accelerometer with Analog Output 1 2 3 4 5 Analog Devices
MAX4372TLow-Cost SOT23 Micropower High-Side Current-Sense Amplifier with Voltage Output 1 2 3 4 5 MoreMaxim Integrated Products
ADIS16003Dual-Axis ±1.7 g Accelerometer with SPI Interface 1 2 3 4 5 MoreAnalog Devices
ADIS16006Dual-Axis +-5 Accelerometer with SPI Interface 1 2 3 4 5 MoreAnalog Devices
UCC28220INTERLEAVED DUAL PWM CONTROLLER WITH PROGRAMMABLE MAX DUTY CYCLE 1 2 3 4 5 MoreTI store
U6081BPWM Power Control with Low Duty Cycle Switch Off 1 2 3 4 5 MoreTEMIC Semiconductors
U6084BPWM Power Control with Automatic Duty Cycle Reduction 1 2 3 4 5 MoreTEMIC Semiconductors
CS2844Current Mode PWM Control Circuit with 50% Max Duty Cycle 1 2 3 4 5 MoreCherry Semiconductor Corporation

Link URL

Czy Alldatasheet okazała się pomocna?  [ DONATE ]  

O Alldatasheet   |   Reklama   |   Kontakt   |   Polityka prywatności   |   Dodaj do ulubionych   |   Linki   |   Lista producentów
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  , Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp  |   Russian : Alldatasheetru.com
Korean : Alldatasheet.co.kr   |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com  |   Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl