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PDF AD704 Data sheet ( Hoja de datos )
| Número de pieza | AD704 | |
| Descripción | Picoampere Input Current Quad Bipolar Op Amp | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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Picoampere Input Current Quad
Bipolar Op Amp
AD704
FEATURES
High dc precision
150 µV maximum offset voltage
1.5 µV/°C maximum offset voltage drift
270 pA maximum input bias current
0.3 pA/°C typical IB drift
Low noise: 0.5 µV p-p
Typical noise: 0.1 Hz to 10 Hz
Low power: 600 µA maximum supply current per amplifier
Dual version: AD706
APPLICATIONS
Industrial/process controls
Weigh scales
ECG/EKG instrumentation
Low frequency active filters
GENERAL DESCRIPTION
The AD704 is a quad, low power bipolar op amp that has the
low input bias current of a BiFET amplifier and offers a signifi-
cantly lower IB drift over temperature. It uses superbeta bipolar
input transistors to achieve picoampere input bias current levels
(similar to FET input amplifiers at room temperature), while its
IB typically increases only by 5× at 125°C (unlike a BiFET amp,
for which IB doubles every 10°C, resulting in a 1000× increase at
125°C). In addition, the AD704 achieves 150 μV offset voltage and
the low noise characteristics of a precision bipolar input op amp.
Because it has only 1/20 the input bias current of an OP07, the
AD704 does not require the commonly used balancing resistor.
Furthermore, the current noise is 1/5 that of the OP07, which
makes the AD704 usable with much higher source impedances.
At 1/6 the supply current (per amplifier) of the OP07, the
AD704 is better suited for today’s higher density circuit boards
and battery-powered applications.
The AD704 is an excellent choice for use in low frequency active
filters in 12- and 14-bit data acquisition systems, in precision
instrumentation, and as a high quality integrator. The AD704 is
internally compensated for unity gain stability. The AD704J is
rated over the commercial temperature range of 0°C to 70°C.
The AD704A is rated over the industrial temperature of −40°C
to +85°C. The AD704S is rated over the military temperature
range of −55°C to +125°C, processed to MIL-STD-883B.
CONNECTION DIAGRAMS
OUTPUT 1
14 OUTPUT
–IN 2
+IN 3
+VS 4
+IN 5
14
AD704
TOP VIEW
13 –IN
12 +IN
11 –VS
10 +IN
–IN 6 2 3 9 –IN
OUTPUT 7
8 OUTPUT
(Not to Scale)
Figure 1. 14-Lead Plastic DIP (N)
OUTPUT 1
16 OUTPUT
–IN 2
+IN 3
+VS 4
+IN 5
14
AD704
TOP VIEW
15 –IN
14 +IN
13 –VS
12 +IN
–IN 6
2 3 11 –IN
OUTPUT 7
10 OUTPUT
NC 8 (Not to Scale) 9 NC
NC = NO CONNECT
Figure 2. 16-Lead SOIC (R) Package
+IN1 4
NC 5
+VS 6
NC 7
+IN2 8
100
3 2 1 20 19
14
AD704
TOP VIEW
(Not to Scale)
23
18 +IN4
17 NC
16 –VS
15 NC
14 +IN3
9 10 11 12 13
NC = NO CONNECT
Figure 3. 20-Terminal LCC
(E-20-1) Package
10
TYPICAL JFET AMP
1
0.1
AD704
0.01
–55
25
TEMPERATURE (°C)
125
Figure 4. Input Bias Current Over Temperature
Table 1. Low IB @ 125°C
Model 30V
16V
Single N/A
AD8663
Dual AD706 AD8667
Quad AD704 AD8669
1.3 to 5V
AD8603
AD8607
AD8609
Next Generation
N/A
AD8622
AD8624
Rev. E
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. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2001-2010 Analog Devices, Inc. All rights reserved.
1 page  
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter
Rating
Supply Voltage
±18 V
Internal Power Dissipation (25°C)1
Input Voltage
±VS
Differential Input Voltage2
±0.7 V
Output Short-Circuit Duration (Single Input) Indefinite
Storage Temperature Range
−65°C to +125°C
Operating Temperature Range
AD704J
0°C to 70°C
AD704A
−40°C to +85°C
Lead Temperature (Soldering, 10 sec)
300°C
1 Specification is for the device in free air:
14-lead plastic package: θJA = 150°C/W.
16-lead SOIC package: θJA = 100°C/W.
20-terminal LCC package: θJA = 150°C/W.
2 The input pins of this amplifier are protected by back-to-back diodes. If the
differential voltage exceeds ±0.7 volts, external series protection resistors
should be added to limit the input current to less than 25 mA.
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
9kΩ
1kΩ
INPUT SIGNAL1
1kΩ
1/4
AD704
+VS
OUTPUT
0.1µF
COM
2.5kΩ
0.1µF
–VS
AD704
PIN 4
1µF
1µF AD704
PIN 11
NOTES
1. ALL FOUR AMPLIFIERS ARE CONNECTED AS SHOWN.
1THE SIGNAL INPUT (SUCH THAT THE AMPLIFIER’S OUTPUT IS AT MAXIMUM
AMPLITUDE WITHOUT CLIPPING OR SLEW LIMITING) IS APPLIED TO ONE
AMPLIFIER AT A TIME. THE OUTPUTS OF THE OTHER THREE AMPLIFIERS ARE
THEN MEASURED FOR CROSSTALK.
Figure 5. Crosstalk Test Circuit
AD704
–80
–100
–120
AMP4
AMP2
AMP3
–140
–160
10
100 1k 10k
FREQUENCY (Hz)
Figure 6. Crosstalk vs. Frequency
ESD CAUTION
100k
Rev. E | Page 5 of 16
5 Page 
AD704
THEORY OF OPERATION
OPTIONAL
AC CMRR TRIM
R5 R4
2.4kΩ 47.5kΩ
GAIN TRIM
(500kΩ POT)
RG
R3
6.34kΩ
R1
6.34kΩ
DC
CMRR
TRIM
(5kΩ POT)
–VIN
Ct
+VS
0.1µF
1/4
AD704
R2
49.9kΩ
1/4
AD704
0.1µF
R6
1MΩ
Q1 =
C1
4C2
ω= 1
R6 C1C2
R6 = R7
C1
R7
1MΩ
C2
1/4
AD704
Q2 =
C3
4C4
ω= 1
R8 C3C4
R8 = R9
C3
R8
1MΩ
R9
1MΩ
C4
1/4
AD704
OUTPUT
+VIN
–VS R10, 2MΩ
C5, 0.01µF
R11, 2MΩ
C6, 0.01µF
OPTIONAL BALANCE RESISTOR NETWORKS
CAN BE REPLACED WITH A SHORT.
NOTES
1. INSTRUMENTATION
AMPLIFIER
GAIN
=
1
+
R2
R1
+2RRG2
(FOR R1 = R3, R2 = R4 + R5).
2. CAPACITORS C2 AND C4 ARE SOUTHERN ELECTRONICS MPCC, POLYCARBONATE, ±5%, 50V.
3. ALL RESISTORS METAL FILM, 1%.
Figure 34. Gain-of-10 Instrumentation Amplifier with Post Filtering
The instrumentation amplifier with post filtering (see Figure 34)
combines two applications that benefit greatly from the AD704.
This circuit achieves low power and dc precision over temperature
with a minimum of components.
The instrumentation amplifier circuit offers many performance
benefits, including BiFET level input bias currents, low input
offset voltage drift, and only 1.2 mA quiescent current. It operates
for gains that are G ≥ 2 and, at lower gains, it benefits from no
output amplifier offset and no noise contribution as encountered
in a 3-op-amp design. Good low frequency CMRR is achieved
even without the optional ac CMRR trim (see Figure 35). Table 4
provides resistance values for three common circuit gains. For
other gains, use the following equations:
R2 = R4 + R5 = 49.9 kΩ
R1 = R3 = 49.9 kΩ
0.9 G − 1
160
GAIN = 10, 0.2V p-p COMMON-MODE INPUT
140
CIRCUIT TRIMMED
120 USING CAPACITOR Ct
100
80
TYPICAL MONOLITHIC IN AMP
60
40 WITHOUT CAPACITOR Ct
20
0
1 10 100 1k 10k
FREQUENCY (Hz)
Figure 35. Common-Mode Rejection vs. Frequency with and Without
Capacitor Ct
Max Value of
RG
=
99.8 kΩ
0.06 G
Ct
≈
2π
1
(R3) 5 × 105
Table 4. Resistance Values for Various Gains
Circuit
RG (Max Value of
Gain (G) R1 and R3 Trim Potentiometer)
10
6.34 kΩ
166 kΩ
100
526 Ω
16.6 kΩ
1000
56.2 Ω
1.66 kΩ
Bandwidth
(−3 dB), Hz
50 k
5k
0.5 k
Rev. E | Page 11 of 16
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet AD704.PDF ] | |
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