Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF Download HTML

AD8553 Datasheet(PDF) 21 Page - Analog Devices

Part No. AD8553
Description  Wide Supply Range, Micropower,
Download  28 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  AD [Analog Devices]
Homepage  http://www.analog.com
Logo 

AD8553 Datasheet(HTML) 21 Page - Analog Devices

Zoom Inzoom in Zoom Outzoom out
 21 / 28 page
background image
Data Sheet
AD8420
Rev. 0 | Page 21 of 28
Reference
LAYOUT
The output voltage of the AD8420 is developed with respect to
the potential on the reference terminal. Take care to tie REF to the
appropriate local ground. The differential voltage at the inputs is
reproduced between the REF and FB pins; therefore, it is important
to set VREF so that the voltage at FB does not exceed the input range.
Common-Mode Rejection Ratio over Frequency
Poor layout can cause some of the common-mode signal to be
converted to a differential signal before reaching the in-amp. This
conversion can occur when the path to the positive input pin
has a different frequency response than the path to the negative
input pin. For best CMRR vs. frequency performance, the input
source impedance and capacitance of each path should be closely
matched. This includes connecting Pin 1 to −VS, which matches the
parasitic capacitance and the leakage between the inputs and
adjacent pins. Place additional source resistance in the input
path (for example, for input protection) close to the in-amp inputs
to minimize their interaction with the parasitic capacitance from
the printed circuit board (PCB) traces.
DRIVING THE REFERENCE PIN
Traditional instrumentation amplifier architectures require the
reference pin to be driven with a low impedance source. In these
architectures, impedance at the reference pin degrades both CMRR
and gain accuracy. With the AD8420 architecture, resistance at
the reference pin has no effect on CMRR.
AD8420
+IN
–IN
REF
FB
VOUT
G = 1 +
R2 + RREF
R1
VREF
R1
R2
RREF
Power Supplies
Use a stable dc voltage to power the instrumentation amplifier.
Noise on the supply pins can adversely affect performance. For
more information, see the PSRR performance curves in Figure 24
and Figure 25.
Place a 0.1 μF capacitor as close as possible to each supply pin.
As shown in Figure 62, a 10 μF tantalum capacitor can be used
farther away from the part. This capacitor, which is intended to
be effective at low frequencies, can usually be shared by other
precision integrated circuits. Keep the traces between these
integrated circuits short to minimize interaction of the trace
parasitic inductance with the shared capacitor.
Figure 63. Calculating Gain with Reference Resistance
Resistance at the reference pin does affect the gain of the AD8420,
but if this resistance is constant, the gain setting resistors can be
adjusted to compensate. For example, the AD8420 can be driven
with a voltage divider as shown in Figure 64.
R1
R2
AD8420
+VS
+IN
–IN
0.1µF
10µF
0.1µF
10µF
–VS
VOUT
AD8420
+IN
–IN
REF
FB
VOUT
G = 1 +
R2 + R3
||R4
R1
R1
R2
R3
R4
VS
Figure 64. Using Resistor Divider to Set Reference Voltage
Figure 62. Supply Decoupling, REF, and Output Referred to Local Ground


Html Pages

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28 


Datasheet Download




Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : 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  |   Vietnamese : Alldatasheet.vn