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


ADXL190 Datasheet(Arkusz danych) 4 Page - Analog Devices

Numer części ADXL190
Szczegółowy opis  Low Cost -100 gSingle Axis Accelerometer with Analog Output
Pobierz  5 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Producent  AD [Analog Devices]
Strona internetowa  http://www.analog.com
Logo 

   
 4 page
background image
REV. 0
ADXL190
–4–
APPLICATIONS
All the circuitry needed to drive the sensor and convert the
capacitance change to voltage is incorporated on-chip requiring
no external components except for standard power supply de-
coupling. Both sensitivity and the zero-g value are ratiometric to
the supply voltage, so that ratiometric devices following the
accelerometer (such as an ADC, etc.) will track the accelerom-
eter if the supply voltage changes. The output voltage (VOUT) is
a function of both the acceleration input (a) and the power
supply voltage (VS) as follows:
VOUT = VS/2 – (Sensitivity × VS/5 V × a)
Adjusting the 0 g Bias Level
In some cases the user may have an asymmetrical input or may
want to fine adjust the zero-g output level to obtain maximum
dynamic range. The zero-g level is adjusted by supplying a
voltage to the zero-g adjustment pin (see Figure 2).
+VS
2
25k
5k
ADXL190
ZERO
g ADJUST
FILTER
VOUT
GAIN = 3
ACCELERATION
SIGNAL
+VS
200k
C2
0.1 F
Figure 2. Optional Zero-g Adjust Circuit Detail
Any voltage difference between the zero-g adjustment pin and
VS/2 is reduced by a factor of 6 by the internal resistor divider.
This is then gained by the factor of 3 in the output stage for a
total gain of 0.5 for the zero-g adjustment. (Note: The ratio of
the resistors in the divider is consistent from part-to-part; how-
ever, the absolute values can have a
± 30% tolerance). The
zero-g adjustment voltage can be set up by a variety of methods
including a potentiometer (as shown in Figure 2), a PWM sig-
nal, or with a simple three-state output.
The simplest way is by adding a resistor between the ZERO g
ADJUST pin and VS or ground. The output will be offset by:
Offset (V) = (7.5
× V
S)/(30 + R)
where R is in k
Ω and connected to V
S.
Offset (V) = (–7.5
× V
S)/(30 + R)
where R is in k
Ω and connected to ground.
Resistors may also be connected to microcontroller I/O pins as
shown in Figure 3. Using two I/Os that may be set to VS, ground,
or three-state, there are seven possibilities as shown in Table I
(one cannot set one I/O pin to VS and the other to ground).
Using such a system, any ADXL190 may be user trimmed to
output 2.5 V
± 35 mV at zero g.
Table I. Offsets Produced Using the Circuit in Figure 3 for VS
= 5 V
Offset Voltage
P1
P0
Produced
Offset in g
Three-State
Three-State
0 mV
0
Three-State
0
–71 mV
–4
0
Three-State
–134 mV
–7.4
0
0
–191 mV
–10.6
Three-State
1
71 mV
4
1
Three-State
134 mV
7.4
1
1
191 mV
10.6
Another way to adjust the zero g offset is to supply a voltage to
the ZERO g ADJUST pin. The difference between VS/2 and
the voltage at the ZERO g ADJUST pin is reduced by a factor
of 6 (as a result of the internal 5 k
Ω and 25 kΩ voltage divider)
and then multiplied by a factor of 3 in the output stage of the
ADXL190 resulting in a total gain of 0.5. Offset is thus de-
scribed by the following equation:
Offset (V) = (Voltage at the ZERO g ADJUST Pin – VS/2)/2
This voltage may be produced by a variety of methods includ-
ing a PWM signal from a microcontroller. Care must be taken
that the output impedance of this voltage source is less than
5 k
Ω and that there is very little ripple (noise). Any noise at the
ZERO g ADJUST pin will cause output errors.
If an asymmetric range of acceleration is required (e.g., +75 g
to –125 g) a resistor may be connected between the ZERO g
ADJUST and ground or VS as described above. For example:
For a range of +75 g to –125 g the offset required is –25 g.
–25 g at 18 mV/g = 450 mV of offset is required.
Rearranging the offset equations above:
R = [(7.5
× V
S)/offset] –30 = 53.3 k
Ω connected to ground.
For asymmetric operation the g range midpoint may be shifted
up to
±80 g typically.
500k
250k
ZERO
g
ADJUST
ADXL190
MICROCONTROLLER
P1
P0
Figure 3. An Offset Adjustment Scheme




Html Pages

1  2  3  4  5 


Datasheet Download



Powiązane numery części

Numer częściSzczegółowy opis komponentówHtml ViewProducent
MX210QLow Cost 10g Dual Axis Accelerometer with Analog Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers
MXA6500GLow Cost Low Noise ±1 g Dual Axis Accelerometer with Absolute Analog Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers
MXR7202GLow Cost Low Noise ±2 g Dual Axis Accelerometer with Ratiometric Analog Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers
MX205QLow Cost 5.0g Dual Axis Accelerometer with Analog Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers
MXA2312ALow Cost +2 -2 g Dual Axis Accelerometer with Analog Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers
MXR7210GLow Cost Low Noise ±10 g Dual Axis Accelerometer with Ratiometric Analog Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers
MXR7311GLLow Cost Low Noise ±2 g Dual Axis Accelerometer with Ratiometric Analog Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers
ADXL202Low Cost +-2 g/+-10 g Dual Axis iMEMS Accelerometers with Digital Output 1 2 3 4 5 MoreAnalog Devices
MXA2500JUltra Low Cost ±1.0 g Dual Axis Accelerometer with Absolute Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers
MXA2500UUltra Low Noise 1g Dual Axis Accelerometer with Analog Outputs 1 2 3 4 5 MoreList of Unclassifed Manufacturers

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