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PDF AD624 Data sheet ( Hoja de datos )
| Número de pieza | AD624 | |
| Descripción | Precision Instrumentation Amplifier | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AD624 (archivo pdf) en la parte inferior de esta página. Total 15 Páginas | ||
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FEATURES
Low Noise: 0.2 V p-p 0.1 Hz to 10 Hz
Low Gain TC: 5 ppm max (G = 1)
Low Nonlinearity: 0.001% max (G = 1 to 200)
High CMRR: 130 dB min (G = 500 to 1000)
Low Input Offset Voltage: 25 V, max
Low Input Offset Voltage Drift: 0.25 V/؇C max
Gain Bandwidth Product: 25 MHz
Pin Programmable Gains of 1, 100, 200, 500, 1000
No External Components Required
Internally Compensated
Precision
Instrumentation Amplifier
AD624
FUNCTIONAL BLOCK DIAGRAM
–INPUT
G = 100
G = 200
G = 500
RG1
RG2
+INPUT
50⍀
225.3⍀
4445.7⍀
124⍀
80.2⍀
50⍀
AD624
VB 10k⍀
20k⍀
20k⍀
10k⍀
10k⍀
10k⍀
SENSE
OUTPUT
REF
PRODUCT DESCRIPTION
The AD624 is a high precision, low noise, instrumentation
amplifier designed primarily for use with low level transducers,
including load cells, strain gauges and pressure transducers. An
outstanding combination of low noise, high gain accuracy, low
gain temperature coefficient and high linearity make the AD624
ideal for use in high resolution data acquisition systems.
The AD624C has an input offset voltage drift of less than
0.25 µV/°C, output offset voltage drift of less than 10 µV/°C,
CMRR above 80 dB at unity gain (130 dB at G = 500) and a
maximum nonlinearity of 0.001% at G = 1. In addition to these
outstanding dc specifications, the AD624 exhibits superior ac
performance as well. A 25 MHz gain bandwidth product, 5 V/µs
slew rate and 15 µs settling time permit the use of the AD624 in
high speed data acquisition applications.
The AD624 does not need any external components for pre-
trimmed gains of 1, 100, 200, 500 and 1000. Additional gains
such as 250 and 333 can be programmed within one percent
accuracy with external jumpers. A single external resistor can
also be used to set the 624’s gain to any value in the range of 1
to 10,000.
PRODUCT HIGHLIGHTS
1. The AD624 offers outstanding noise performance. Input
noise is typically less than 4 nV/√Hz at 1 kHz.
2. The AD624 is a functionally complete instrumentation am-
plifier. Pin programmable gains of 1, 100, 200, 500 and 1000
are provided on the chip. Other gains are achieved through
the use of a single external resistor.
3. The offset voltage, offset voltage drift, gain accuracy and gain
temperature coefficients are guaranteed for all pretrimmed
gains.
4. The AD624 provides totally independent input and output
offset nulling terminals for high precision applications.
This minimizes the effect of offset voltage in gain ranging
applications.
5. A sense terminal is provided to enable the user to minimize
the errors induced through long leads. A reference terminal is
also provided to permit level shifting at the output.
REV. C
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
which 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 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1999
1 page  
–140
G = 500
–120
G = 100
–100
G=1
–80
–60
–40
–20
01 10 100 1k 10k 100k 1M 10M
FREQUENCY – Hz
Figure 10. CMRR vs. Frequency RTI,
Zero to 1k Source Imbalance
30
20
G = 500
G = 1, 100
10
G = 1000
G = 100
-
BANDWIDTH LIMITED
0
1k
10k 100k
1M
FREQUENCY – Hz
Figure 11. Large Signal Frequency
Response
AD624
160
140 G = 500
120
–VS = –15V dc+
1V p-p SINEWAVE
100
80
G = 100
60
40
G=1
20
0
10 100 1k 10k 100k
FREQUENCY – Hz
Figure 12. Positive PSRR vs.
Frequency
160
140
G = 500
120
–VS = –15V dc+
1V p-p SINEWAVE
100
80
G = 100
60
40
G=1
20
0
10 100 1k 10k 100k
FREQUENCY – Hz
Figure 13. Negative PSRR vs.
Frequency
1000
100 G = 1
G = 10
10
G = 100, 1000
G = 1000
1
0.1
1
10 100 1k 10k
FREQUENCY – Hz
100k
Figure 14. RTI Noise Spectral
Density vs. Gain
100k
10k
1000
100
10
0.1
1 10 100 10k
FREQUENCY – Hz
100k
Figure 15. Input Current Noise
Figure 16. Low Frequency Voltage
Noise, G = 1 (System Gain = 1000)
Figure 17. Low Frequency Voltage
Noise, G = 1000 (System Gain =
100,000)
–12 TO 12
–8 TO 8
–4 TO 4
OUTPUT
STEP –V
4 TO –4
8 TO –8
12 TO –12
1%
0.1%
0.01%
1%
0.1%
0.01%
0 5 10 15 20
SETTLING TIME – s
Figure 18. Settling Time, Gain = 1
REV. C
–5–
5 Page 
AD624
50⍀
–IN 1
50⍀
+IN 2
3
INPUT
OFFSET
TRIM
4
20k⍀
VB
R1 5
10k⍀
10k⍀
6
10k⍀
–VS
+VS
1F C1
35V
ANALOG
COMMON
7
AD624
8
C2
K1 – K3 =
THERMOSEN DM2C
4.5V COIL
D1 – D3 = IN4148
GAIN TABLE
A B GAIN
00
01
10
11
100
500
200
1
16
80.2⍀
15
4445.7⍀ 14
20k⍀
10k⍀
225.3⍀
124⍀
10k⍀
13
12
11
10
9
OUTPUT
OFFSET
TRIM
R2
10k⍀
G = 100 G = 200 G = 500
K1 K2 K3
NC
RELAY
SHIELDS
OUT
K1 K2 K3
D1 D2 D3
INPUTS A
GAIN
RANGE B
74LS138
DECODER
+5V
Y0
Y1
Y2
7407N
BUFFER
DRIVER
+5V
10F
LOGIC
COMMON
Figure 38. Gain Programmable Amplifier
By establishing a reference at the “low” side of a current setting
resistor, an output current may be defined as a function of input
voltage, gain and the value of that resistor. Since only a small
current is demanded at the input of the buffer amplifier A2, the
forced current IL will largely flow through the load. Offset and
drift specifications of A2 must be added to the output offset and
drift specifications of the IA.
PROGRAMMABLE GAIN
Figure 38 shows the AD624 being used as a software program-
mable gain amplifier. Gain switching can be accomplished with
mechanical switches such as DIP switches or reed relays. It
should be noted that the “on” resistance of the switch in series
with the internal gain resistor becomes part of the gain equation
and will have an effect on gain accuracy.
A significant advantage in using the internal gain resistors in a
programmable gain configuration is the minimization of thermo-
couple signals which are often present in multiplexed data
acquisition systems.
If the full performance of the AD624 is to be achieved, the user
must be extremely careful in designing and laying out his circuit
to minimize the remaining thermocouple signals.
The AD624 can also be connected for gain in the output stage.
Figure 39 shows an AD547 used as an active attenuator in the
output amplifier’s feedback loop. The active attenuation pre-
sents a very low impedance to the feedback resistors therefore
minimizing the common-mode rejection ratio degradation.
Another method for developing the switching scheme is to use a
DAC. The AD7528 dual DAC which acts essentially as a pair of
switched resistive attenuators having high analog linearity and
symmetrical bipolar transmission is ideal in this application. The
multiplying DAC’s advantage is that it can handle inputs of
either polarity or zero without affecting the programmed gain.
The circuit shown uses an AD7528 to set the gain (DAC A) and
to perform a fine adjustment (DAC B).
(+INPUT)
–IN
(–INPUT)
+IN
INPUT
OFFSET
NULL
10k⍀
–VS
+VS
1F
35V
50⍀
1
50⍀
2
3
4 20k⍀
VB
5
10k⍀
6
10k⍀
7
AD624
8
16
80.2⍀
15
14
4445.7⍀
20k⍀
10k⍀
225.3⍀
124⍀
13
12
11
10k⍀
10
OUTPUT
OFFSET
NULL
TO –V
10k⍀
9 VOUT
10pF
+VS
VSS VDD GND
AD711
–VS
AD7590
39.2k⍀
28.7k⍀
316k⍀
1k⍀
1k⍀
1k⍀
A1 A2 A3 A4 WR
Figure 39. Programmable Output Gain
REV. C
–11–
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet AD624.PDF ] | |
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