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PDF OP227 Data sheet ( Hoja de datos )
| Número de pieza | OP227 | |
| Descripción | Dual / Low Noise / Low Offset Instrumentation Operational Amplifier | |
| Fabricantes | Analog Devices | |
| Logotipo |  |
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a
Dual, Low Noise, Low Offset
Instrumentation Operational Amplifier
OP227
FEATURES
Excellent Individual Amplifier Parameters
Low VOS, 80 V Max
Offset Voltage Match, 80 V Max
Offset Voltage Match vs. Temperature, 1 V/؇C Max
Stable VOS vs. Time, 1 V/MO Max
Low Voltage Noise, 3.9 nV/÷Hz Max
Fast, 2.8 V/s Typ
High Gain, 1.8 Million Typ
High Channel Separation, 154 dB Typ
PIN CONNECTIONS
NULL (A) 1
14 V+ (A)
NULL (A) 2
13 OUT (A)
–IN (A) 3
+IN (A) 4
V– (B) 5
A
12 V– (A)
11 +IN (B)
B
10 –IN (B)
OUT (B) 6
9 NULL (B)
V+ (B) 7
8 NULL (B)
NOTE
1. DEVICE MAY BE OPERATED EVEN IF INSERTION
IS REVERSED; THIS IS DUE TO INHERENT SYMMETRY
OF PIN LOCATIONS OF AMPLIFIERS A AND B
2. V–(A) AND V–(B) ARE INTERNALLY CONNECTED VIA
SUBSTRATE RESISTANCE
GENERAL DESCRIPTION
The OP227 is the first dual amplifier to offer a combination of
low offset, low noise, high speed, and guaranteed amplifier matching
characteristics in one device. The OP227, with a VOS match of
25 mV typical, a TCVOS match of 0.3 mV/∞C typical and a 1/f corner
of only 2.7 Hz is an excellent choice for precision low noise designs.
These dc characteristics, coupled with a slew rate of 2.8 V/ms
typical and a small-signal bandwidth of 8 MHz typical, allow the
designer to achieve ac performance previously unattainable with
op amp based instrumentation designs.
When used in a three op amp instrumentation configuration, the
OP227 can achieve a CMRR in excess of 100 dB at 10 kHz. In
addition, this device has an open-loop gain of 1.5 M typical with
a 1 kW load. The OP227 also features an IB of ± 10 nA typical,
an IOS of 7 nA typical, and guaranteed matching of input currents
between amplifiers. These outstanding input current specifications
are realized through the use of a unique input current cancellation
circuit which typically holds IB and IOS to ± 20 nA and 15 nA
respectively over the full military temperature range.
Other sources of input referred errors, such as PSRR and CMRR,
are reduced by factors in excess of 120 dB for the individual
amplifiers. DC stability is assured by a long-term drift application
of 1.0 mV/month.
Matching between channels is provided on all critical param-
eters including offset voltage, tracking of offset voltage versus
temperature, noninverting bias current, CMRR, and power
supply rejection ratio. This unique dual amplifier allows the
elimination of external components for offset nulling and
frequency compensation.
SIMPLIFIED SCHEMATIC
R3 R4
Q6
NULL
R1* R2*
NON
INVERTING
INPUT (+)
INVERTING
INPUT (–)
Q1A Q1B Q2B Q2A
Q3
Q21
Q11 Q12
C2
R23
Q23
Q22
C1
R24
Q24 R9
R12
Q20 Q19
R5 C3 R11 C4
Q26
V+
Q46
OUTPUT
Q45
Q27 Q28
*R1 AND R2 ARE PREMATURELY ADJUSTED AT WAFER TEST FOR MINIMUM OFFSET VOLTAGE.
V-
REV. A
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. 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
www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2002
1 page  
OP227
ABSOLUTE MAXIMUM RATINGS
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 22 V
Input Voltage1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 22 V
Output Short-Circuit Duration . . . . . . . . . . . . . . . . . Indefinite
Differential Input Voltage2 . . . . . . . . . . . . . . . . . . . . . . . ± 0.7 V
Differential Input Current2 . . . . . . . . . . . . . . . . . . . . . ± 25 mA
Storage Temperature Range . . . . . . . . . . . . . –65∞C to +150∞C
Operating Temperature Range
OP227E, OP227G . . . . . . . . . . . . . . . . . . . . –25∞C to +85∞C
Lead Temperature (Soldering 60 sec) . . . . . . . . . . . . . . 300∞C
NOTES
1For supply voltages less than ± 22 V, the absolute maximum input voltage is equal
to the supply voltage.
2The OP227 inputs are protected by back-to-back diodes. Current limiting resistors
are not used in order to achieve low noise. If differential input voltage exceeds ± 0.7
V, the input current should be limited to 25 mA.
3JA is specified for worst-case mounting conditions, i.e., JA is specified for device
in socket for CERDIP package.
THERMAL CHARACTERISTICS
Thermal Resistance
14-Lead CERDIP
JA3 = 106∞C/W
JC = 16∞C/W
ORDERING GUIDE
TA = 25؇C
VOS MAX (V)
80
180
Hermetic
DIP 14-Lead
OP227EY
OP227GY
Operating
Temperature Range
IND
IND
For military processed devices, please refer to the Standard
Microcircuit Drawing (SMD) available at
www.dscc.dla.mil/programs/milspec/default.asp.
SMD Part Number
ADI Equivalent
5962-8688701CA*
OP227AYMDA
*Not recommended for new design, obsolete April 2002.
CAUTION
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily
accumulate on the human body and test equipment and can discharge without detection. Although
the OP227 features propriety ESD protection circuitry, permanent damage may occur on devices
subjected to high energy electrostatic discharges. Therefor, proper ESD precautions are
recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
REV. A
–5–
5 Page 
OP227
Dynamic range is limited by A1 as well as A2. The output of A1
is:
V1
=
–ÊËÁ1 +
RN
RO
ˆ
¯˜
V
d
+ 2 VCM
If the instrumentation amplifier was designed for a gain of 10
and maximum Vd of ± 1 V, then RN/RO would need to be four
and VO would be a maximum of ± 10 V. Amplifier A1 would have
a maximum output of ± 5 V plus 2 VCM, thus a limit of ± 10 V
on the output of A1 would imply a limit of ± 2.5 V on VCM. A
nominal value of 10 kW for RN is suitable for most applications.
A range of 20 W to 2.5 kW for RO will then provide a gain range
of 10 to 1000. The current through RO is Vd/RO, so the amplifiers
must supply ± 10 mV/20 W (or ± 0.5 mA) when the gain is at the
maximum value of 1000 and Vd is at ± 10 mV.
For Ad/A01 < 1, this simplifies to (2Ad/A01) 3 VCM. If the op amp
gain is 700 V/mV, VCM is 2.5 V, and Ad is set to 700, then the
error at the output due to this effect will be approximately 5 mV.
A compete instrumentation amplifier designed for a gain of 100
is shown in Figure 3. It has provision for trimming of input
offset voltage, CMR, and gain. Performance is excellent due to
the high gain, high CMR, and low noise of the individual ampli-
fiers combined with the tight matching characteristics of the
OP227 dual.
CMR
10k⍀
0.1%
50⍀
OFFSET
V+
10k⍀
ADJUST
2 1 14
Rejecting common-mode inputs is important in accurately
amplifying low level differential signals. Two factors determine
the CMR in this instrumentation amplifier configuration (assuming
infinite gain):
∑ CMR of the op amps
∑ Matching of the resistor network ratios (R3/R4 = R2/R1)
VCM – 1/2Vd
GAIN
9.95k⍀
3
4
2.5k⍀
13
12 V–
In this instrumentation amplifier configuration error due to CMR
effect is directly proportional to the CMR match of the op amps.
For the OP227, this DCMR is a minimum of 97 dB for the “G”
and 110 dB for the “E” grades. A DCMR value of 100 dB and a
common-mode input range of ± 2.5 V indicates a peak input-
referred error of only ± 25 mV. Resistor matching is the other
factor affecting CMR. Defining Ad as the differential gain of the
instrumentation amplifier and assuming that R1, R2, R3, and R4
are approximately equal (RN will be the nominal value), then CMR
for this instrumentation amplifier configuration will be approxi-
mately Ad divided by 4⌬R/RN. CMR at differential gain of 100
would be 88 dB with resistor matching of 0.01%. Trimming R1
to make the ratio R3/R4 equal to R2/R1 will raise the CMR
until limited by linearity and resistor stability considerations.
191⍀
10
VCM – 1/2Vd
11
OP227
7 V+
6 VO = 100Vd
5 V–
10k⍀, 0.1%
10k⍀, 0.1%
Figure 3. Two Op Amp Instrumentation Amplifier Using
OP227 Dual
The high open-loop gain of the OP227 is very important to
achieving high accuracy in the two op amp instrumentation
amplifier configuration. Gain error can be approximated by:
Gain Error ف 1
1+
Ad
AO2
, Ad
2 AO1 AO1
<1
where Ad is the instrumentation amplifier differential gain and
AO2 is the open loop gain of op amp A2. This analysis assumes
equal values of R1, R2, R3, and R4. For example, consider an
OP227 with AO2 of 700 V/mV. Id the differential gain Ad were
set to 700, then the gain error would be 1/1.001, which is
approximately 0.1%.
Another effect of finite op amp gain is undesired feedthrough of
A three op amp instrumentation amplifier configuration using
the OP227 and OP27 is recommended for applications requir-
ing high accuracy over a wide gain range. This circuit provides
excellent CMR over a wide frequency range. As with the two op
amp instrumentation amplifier circuits, the tight matching of the
two op amps within the OP227 package provides a real boost in
performance. Also, the low noise, low offset, and high gain of
the individual op amps minimize errors.
A simplified schematic is shown in Figure 4. The input stage
(A1 and A2) serves to amplify the differential input Vd without
amplifying the common-mode voltage VCM. The output stage
then rejects the common-mode input. With ideal op amps and
no resistor matching errors, the outputs of each amplifier will
be:
common-mode input. Defining AO1 as the open-loop gain of op
amp A1, then the common-mode error (CME) at the output
due to this effect would be approximately:
V1
=
–ÊËÁ1 +
2RRO1ˆ¯˜
Vd
2
+ VCM
CME ف 2Ad
1+
Ad
AO2
,
1
AO1
VCM
V2
=
–ÊËÁ1 +
2RRO1ˆ¯˜
Vd
2
+ VCM
VO = V2 – V1 = ÊËÁ1 + 2RRO1ˆ¯˜ Vd
REV. A
–11–
VO = Ad Vd
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet OP227.PDF ] | |
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