The OP162 (single), OP262 (dual), OP462 (quad) rail-to-rail
15 MHz amplifiers feature the extra speed new designs require,
with the benefits of precision and low power operation. With
their incredibly low offset voltage of 45 µV (typ) and low noise,
they are perfectly suited for precision filter applications and
instrumentation. The low supply current of 500 µA (typ) is
critical for portable or densely packed designs. In addition, the
rail-to-rail output swing provides greater dynamic range and
control than standard video amplifiers provide.
These products operate from single supplies as low as +2.7 V to
dual supplies of ±6 V. The fast settling times and wide output
swings recommend them for buffers to sampling A/D converters.
The output drive of 30 mA (sink and source) is needed for
many audio and display applications; more output current can
be supplied for limited durations.
The OP162 family is specified over the extended industrial
temperature range (–40°C to +125°C). The single OP162
and dual OP262 are available in 8-lead PDIP, SOIC and
TSSOP packages. The quad OP462 is available in 14-lead
PDIP, narrow-body SOIC and TSSOP packages.
: 1 V/ⴗC typ
OS
Operational Amplifiers
OP162/OP262/OP462
PIN CONFIGURATIONS
8-Lead Narrow-Body SO 8-Lead Plastic DIP
(S Suffix) (P Suffix)
1
NULL
–IN A
OP162
+IN A
4
V–
NC = NO CONNECT
8-Lead Narrow-Body SO 8-Lead Plastic DIP
(S Suffix) (P Suffix)
1
OUT A
OP262
+IN A
4
V–
14-Lead Narrow-Body SO 14-Lead Plastic DIP
(S Suffix) (P Suffix)
NULL
8
V+
OUT A
NC
5
8-Lead TSSOP
(RU Suffix)
8
V+
OUT B–IN A
–IN B
+IN B
5
8-Lead TSSOP
(RU Suffix)
NULL
–IN A
+IN A
V–
OUT A
–IN A
+IN A
V–
1
OP162
2
3
4
NC = NO CONNECT
1
OP262
2
3
4
8
7
6
5
8
7
6
5
NULL
V+
OUT A
NC
V+
OUT B
–IN B
+IN B
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.
For supply voltages greater than 6 volts, the input voltage is limited to less than or
equal to the supply voltage.
2
For differential input voltages greater than 0.6 volts the input current should be
limited to less than 5 mA to prevent degradation or destruction of the input devices.
3
θJA is specified for the worst case conditions, i.e., θ
for P-DIP package; θ
TSSOP packages.
is specified for device soldered in circuit board for SOIC and
JA
is specified for device in socket
JA
ORDERING GUIDE
TemperaturePackagePackage
ModelRangeDescriptionOption
OP162GP–40°C to +125°C 8-Lead Plastic DIP N-8
OP162GS–40°C to +125°C 8-Lead SOICSO-8
OP162HRU –40°C to +125°C 8-Lead TSSOPRU-8
OP262DRU –40°C to +125°C 8-Lead TSSOPRU-8
OP262GP–40°C to +125°C 8-Lead Plastic DIP N-8
OP262GS–40°C to +125°C 8-Lead SOICSO-8
OP262HRU –40°C to +125°C 8-Lead TSSOPRU-8
OP462DRU –40°C to +125°C 14-Lead TSSOPRU-14
OP462DS–40°C to +125°C 14-Lead SOICSO-14
OP462GP–40°C to +125°C 14-Lead Plastic DIP N-14
OP462GS–40°C to +125°C 14-Lead SOICSO-14
OP462HRU –40°C to +125°C 14-Lead TSSOPRU-14
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 OP162/OP262/OP462 features proprietary ESD protection circuitry, permanent
damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper
ESD precautions are recommended to avoid performance degradation or loss of functionality.
WARNING!
ESD SENSITIVE DEVICE
REV. C
–5–
Page 6
OP162/OP262/OP462–Typical Characteristics
250
VS = 5V
T
= 25ⴗC
200
150
100
QUANTITY – Amplifiers
50
0
–200 –14016 0100–20 40–80
INPUT OFFSET VOLTAGE – V
A
COUNT =
720 OP AMPS
Figure 1. OP462 Input Offset Voltage
Distribution
125
V
100
75
50
25
INPUT OFFSET VOLTAGE –
0
–25 0 2575 100 12550
–75 –50150
TEMPERATURE – ⴗC
VS = 5V
Figure 4. OP462 Input Offset Voltage
vs. Temperature
Figure 5. OP462 Input Bias Current
vs. Temperature
420
VS = 5V
340
260
180
INPUT BIAS CURRENT – nA
100
0 0.5
1.0 1.5 2.0 2.5 3.0 3.5 4.0
COMMON-MODE VOLTAGE – Volts
Figure 3. OP462 Input Bias Current
vs. Common-Mode Voltage
15
VS = 5V
10
5
INPUT OFFSET CURRENT – nA
0
–25 0 2575 100 12550
–75 –50150
TEMPERATURE – ⴗC
Figure 6. OP462 Input Offset Current
vs. Temperature
5.12
VS = 5V
5.06
I
= 250A
5.00
4.94
4.88
OUTPUT HIGH VOLTAGE – Volts
4.82
–75 –50150
–25 0 2575 100 12550
OUT
I
= 5mA
OUT
TEMPERATURE – ⴗC
Figure 7. OP462 Output High Voltage
vs. Temperature
0.100
0.080
0.060
0.040
0.020
OUTPUT LOW VOLTAGE – mV
0.000
–25 0 2575 100 12550
–75 –50150
TEMPERATURE – ⴗC
I
I
OUT
OUT
VS = 5V
= 5mA
= 250A
Figure 8. OP462 Output Low Voltage
vs. Temperature
100
RL = 10k⍀
80
60
40
20
OPEN-LOOP GAIN – V/mV
0
–75 –50150
RL = 2k⍀
RL = 600⍀
–25 0 2575 100 12550
TEMPERATURE – ⴗC
VS = 5V
Figure 9. OP462 Open-Loop Gain
vs. Temperature
–6–
REV. C
Page 7
OP162/OP262/OP462
100
80
60
40
OUTPUT VOLTAGE – mV
20
0
VS = 10V
017
LOAD CURRENT – mA
VS = 3V
23456
Figure 10. Output Low Voltage to
Supply Rail vs. Load Current
50
40
30
20
10
GAIN – dB
0
–10
–20
–30
100k1M100M
GAIN
FREQUENCY – Hz
VS = 5V
= 25ⴗC
T
A
10M
PHASE
45
90
135
180
225
270
Figure 13. Open-Loop Gain and
Phase vs. Frequency (No Load)
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
SUPPLY CURRENT – mA
0.2
0.1
0
–75 –50150
VS = 5V
–25 0 2575 100 12550
TEMPERATURE – ⴗC
VS = 10V
VS = 3V
Figure 11. Supply Current/Amplifier
vs. Temperature
60
VS = 5V
T
= +25ⴗC
A
R
L
C
L
1M10M
PHASE SHIFT – dB
40
20
0
–20
CLOSED-LOOP GAIN – dB
–40
10k100k100M
FREQUENCY – Hz
Figure 14. Closed-Loop Gain vs.
Frequency
= 830⍀
5pF
0.7
0.6
0.5
SUPPLY CURRENT – mA
0.4
021246810
SUPPLY VOLTAGE – Volts
TA = 25ⴗC
Figure 12. OP462 Supply Current/
Amplifier vs. Supply Voltage
5
4
3
VS = 5V
2
A
= 1
VCL
R
= 10k⍀
L
C
= 15pF
L
1
= 25°C
T
A
MAXIMUM OUTPUT SWING – V p-p
DISTORTION < 1%
0
10k100k10M
FREQUENCY – Hz
1M
Figure 15. Maximum Output Swing
vs. Frequency
4
3
VS = 5V
2
= 25ⴗC
T
A
1
0
–1
STEP SIZE – Volts
–2
–3
–4
02001000
0.1% 0.01%
0.1% 0.01%
400600800
SETTLING TIME – ns
Figure 16. Settling Time vs. Step Size
60
50
VS = 5V
T
= 25ⴗC
A
40
V
= ⴞ50mV
IN
R
= 10k⍀
L
30
20
OVERSHOOT – %
10
0
101001000
+OS
–OS
CAPACITANCE – pF
Figure 17. Small-Signal Overshoot
vs. Capacitance
70
60
50
40
30
20
NOISE DENSITY – nV/ Hz
10
0
1101k100
FREQUENCY – Hz
VS = 5V
T
= 25ⴗC
A
Figure 18. Voltage Noise Density vs.
Frequency
REV. C
–7–
Page 8
OP162/OP262/OP462–Typical Characteristics
7
6
5
4
3
2
NOISE DENSITY – pA/ Hz
1
0
110 1k
FREQUENCY – Hz
VS = 5V
T
100
= 25ⴗC
A
Figure 19. Current Noise Density vs.
Frequency
90
80
70
60
50
PSRR – dB
40
30
20
1k10k10M
FREQUENCY – Hz
VS = 5V
T
= 25ⴗC
A
–PSRR+PSRR
100k1M
Figure 22. PSRR vs. Frequency
300
250
200
150
A
= 10
VCL
100
OUTPUT IMPEDANCE – ⍀
50
0
100k1M10M
FREQUENCY – Hz
VS = 5V
T
= 25ⴗC
A
A
= 1
VCL
Figure 20. Output Impedance vs.
Frequency
20mV
100
90
10
0%
VS = 5V
= 100k⍀
A
V
= 0.5V p-p
e
n
2s
Figure 23. 0.1 Hz to 10 Hz Noise
90
80
70
60
50
CMRR – dB
40
30
20
1k10k10M
FREQUENCY – Hz
VS = 5V
T
= 25ⴗC
A
100k1M
Figure 21. CMRR vs. Frequency
2V
100
90
10
0%
2V
VIN = 12V p-p
= ⴞ5V
V
S
= 1
A
V
20s
Figure 24. No Phase Reversal; [VIN =
12 V p-p, V
= ±5 V, AV = 1]
S
100
90
10
0%
20mV
VS = 5V
= 1
A
V
= 25ⴗC
T
A
= 100pF
C
L
200ns
Figure 25. Small Signal Transient
Response
VS = 5V
= 1
A
V
100
90
= 25ⴗC
T
A
= 100pF
C
L
10
0%
500mV
100s
Figure 26. Large Signal Transient
Response
–8–
REV. C
Page 9
OP162/OP262/OP462
APPLICATIONS SECTION
Functional Description
The OPx62 family is fabricated using Analog Devices’ high
speed complementary bipolar process, also called XFCB. The
process includes trench isolating each transistor to lower parasitic capacitances thereby allowing high speed performance.
This high speed process has been implemented without trading
off the excellent transistor matching and overall dc performance
characteristic of Analog Devices’ complementary bipolar process. This makes the OPx62 family an excellent choice as an
extremely fast and accurate low voltage op amp.
Figure 27 shows a simplified equivalent schematic for the OP162.
A PNP differential pair is used at the input of the device. The
cross connecting of the emitters is used to lower the transconductance of the input stage, which improves the slew rate of the
device. Lowering the transconductance through cross connecting the emitters has another advantage in that it provides a
lower noise factor than if emitter degeneration resistors were
used. The input stage can function with the base voltages taken
all the way to the negative power supply, or up to within 1 V of
the positive power supply.
V
CC
+IN
V
–IN
V
EE
OUT
Figure 27. Simplified Schematic
Two complementary transistors in a common-emitter configuration are used for the output stage. This allows the output of the
device to swing to within 50 mV of either supply rail at load
currents less than 1 mA. As load current increases, the maximum voltage swing of the output will decrease. This is due to
the collector-to-emitter saturation voltages of the output transistors increasing. The gain of the output stage, and consequently
the open-loop gain of the amplifier, is dependent on the load
resistance connected at the output. And because the dominant
pole frequency is inversely proportional to the open-loop gain,
the unity-gain bandwidth of the device is not affected by the
load resistance. This is typically the case in rail-to-rail output
devices.
Offset Adjustment
Because the OP162/OP262/OP462 has such an exceptionally
low typical offset voltage, adjustment to correct offset voltage
may not be needed. However, the OP162 does have pinouts
where a nulling resistor can be attached. Figure 28 shows how
the OP162 offset voltage can be adjusted by connecting a potentiometer between Pins 1 and 8, and connecting the wiper to
VCC. It is important to avoid accidentally connecting the wiper
to V
, as this will damage the device. The recommended value
EE
for the potentiometer is 20 kΩ.
+5V
20k⍀
1
8
3
2
OP162
–5V
7
6
4
V
OS
Figure 28. Schematic Showing Offset Adjustment
Rail-to-Rail Output
The OP162/OP262/OP462 has a wide output voltage range that
extends to within 60 mV of each supply rail with a load current
of 5 mA. Decreasing the load current will extend the output
voltage range even closer to the supply rails. The commonmode input range extends from ground to within 1 V of the
positive supply. It is recommended that there be some minimal
amount of gain when a rail-to-rail output swing is desired. The
minimum gain required is based on the supply voltage and can
be found as:
V
=
VS–1
S
A
V,min
where VS is the positive supply voltage. With a single supply
voltage of +5 V, the minimum gain to achieve rail-to-rail output
should be 1.25.
Output Short-Circuit Protection
To achieve a wide bandwidth and high slew rate, the output of
the OP162/OP262/OP462 is not short-circuit protected. Shorting the output directly to ground or to a supply rail may destroy
the device. The typical maximum safe output current is ±30 mA.
Steps should be taken to ensure the output of the device will not
be forced to source or sink more than 30 mA.
In applications where some output current protection is needed,
but not at the expense of reduced output voltage headroom, a
low value resistor in series with the output can be used. This is
shown in Figure 29. The resistor is connected within the feedback loop of the amplifier so that if V
and V
swings up to +5 V, the output current will not exceed
IN
is shorted to ground
OUT
30 mA.
For single +5 V supply applications, resistors less than 169 Ω
are not recommended.
+5V
V
IN
OPx62
169⍀
V
OUT
Figure 29. Output Short-Circuit Protection
REV. C
–9–
Page 10
OP162/OP262/OP462
Input Overvoltage Protection
The input voltage should be limited to ±6 V or damage to the
device can occur. Electrostatic protection diodes placed in the
input stage of the device help protect the amplifier from static
discharge. Diodes are connected between each input as well as
from each input to both supply pins as shown in the simplified
equivalent circuit in Figure 27. If an input voltage exceeds
either supply voltage by more than 0.6 V, or if the differential
input voltage is greater than 0.6 V, these diodes begin to energize and overvoltage damage could occur. The input current
should be limited to less than 5 mA to prevent degradation or
destruction of the device.
This can be done by placing an external resistor in series with
the input that could be overdriven. The size of the resistor can
be calculated by dividing the maximum input voltage by 5 mA.
For example, if the differential input voltage could reach 5 V,
the external resistor should be 5 V/5 mA = 1 kΩ. In practice,
this resistance should be placed in series with both inputs to
balance any offset voltages created by the input bias current.
Output Phase Reversal
The OP162/OP262/OP462 is immune to phase reversal as long
as the input voltage is limited to ±6 V. Figure 24 shows a photo
of the output of the device with the input voltage driven beyond
the supply voltages. Although the device’s output will not
change phase, large currents due to input overvoltage could
result, damaging the device. In applications where the possibility
of an input voltage exceeding the supply voltage exists, overvoltage protection should be used, as described in the previous
section.
Power Dissipation
The maximum power that can be safely dissipated by the
OP162/OP262/OP462 is limited by the associated rise in junction temperature. The maximum safe junction temperature is
150°C, and should not be exceeded or device performance
could suffer. If this maximum is momentarily exceeded, proper
circuit operation will be restored as soon as the die temperature
is reduced. Leaving the device in an “overheated” condition for
an extended period can result in permanent damage to the device.
To calculate the internal junction temperature of the OPx62,
the following formula can be used:
T
= P
J
×θJA + T
DISS
A
where: TJ = OPx62 junction temperature;
P
= OPx62 power dissipation;
DISS
θ
= OPx62 package thermal resistance, junction-to-
JA
ambient; and
T
= Ambient temperature of the circuit.
A
The power dissipated by the device can be calculated as:
P
where:I
= I
DISS
is the OPx62 output load current;
LOAD
V
is the OPx62 supply voltage; and
S
V
is the OPx62 output voltage.
OUT
LOAD
× (VS – V
OUT
)
Figures 30 and 31 provide a convenient way to see if the device
is being overheated. The maximum safe power dissipation can
be found graphically, based on the package type and the ambient temperature around the package. By using the previous
equation, it is a simple matter to see if P
exceeds the device’s
DISS
power derating curve. To ensure proper operation, it is important to observe the recommended derating curves shown in
Figures 30 and 31.
2.0
1.5
1.0
0.5
MAXIMUM POWER DISSIPATION – Watts
8-PIN DIP
PACKAGE
8-PIN SOIC
PACKAGE
8-PIN TSSOP
PACKAGE
0
–40120–20020406080100
AMBIENT TEMPERATURE – ⴗC
Figure 30. Maximum Power Dissipation vs. Temperature
for 8-Pin Package Types
2.0
14-PIN DIP
PACKAGE
1.5
14-PIN SOIC
PACKAGE
1.0
14-PIN TSSOP
PACKAGE
0.5
MAXIMUM POWER DISSIPATION – Watts
0
–40120–20020406080100
AMBIENT TEMPERATURE – ⴗC
Figure 31. Maximum Power Dissipation vs. Temperature
for 14-Pin Package Types
Unused Amplifiers
It is recommended that any unused amplifiers in a dual or a
quad package be configured as a unity gain follower with a 1 kΩ
feedback resistor connected from the inverting input to the
output and the noninverting input tied to the ground plane.
Power On Settling Time
The time it takes for the output of an op amp to settle after a
supply voltage is delivered can be an important consideration in
some power-up sensitive applications. An example of this
would be in an A/D converter where the time until valid data
can be produced after power-up is important.
The OPx62 family has a rapid settling time after power-up.
Figure 32 shows the OP462 output settling times for a single
supply voltage of V
= +5 V. The test circuit in Figure 33 was
S
used to find the power on settling times for the device.
–10–
REV. C
Page 11
OP162/OP262/OP462
2V
100
90
10
0%
50mV
Figure 32. Oscilloscope Photo of VS and V
+1
0 TO +5V
SQUARE
+
–
OP462
VS = 5V
A
= 1
V
= 10k⍀
R
L
500ns
10k⍀
OUT
V
OUT
Figure 33. Test Circuit for Power On Settling Time
Capacitive Load Drive
The OP162/OP262/OP462 is a high speed, extremely accurate
device and can tolerate some capacitive loading at its output.
As load capacitance increases, however, the unity-gain bandwidth of the device will decrease. There will also be an increase
in overshoot and settling time for the output. Figure 35 shows
an example of this with the device configured for unity gain and
driving a 10 kΩ resistor and 300 pF capacitor placed in parallel.
By connecting a series R-C network, commonly called a “snubber” network, from the output of the device to ground, this
ringing can be eliminated and overshoot can be significantly
reduced. Figure 34 shows how to set up the snubber network,
and Figure 36 shows the improvement in output response with
the network added.
+5V
OPx62
V
IN
R
X
C
X
V
OUT
C
L
Figure 34. Snubber Network Compensation for Capacitive
Loads
VS = 5V
A
= 1
1s
V
C
L
R
L
= 300pF
= 10k⍀
100
90
10
0%
50mV
Figure 35. A Photo of a Ringing Square Wave
VS = 5V
= 1
A
100
90
10
0%
50mV1s
V
= 300pF
C
L
= 10k⍀
R
L
WITH SNUBBER:
R
= 140⍀
X
= 10nF
C
X
Figure 36. A Photo of a Nice Square Wave at the Output
The network operates in parallel with the load capacitor, CL,
and provides compensation for the added phase lag. The actual
values of the network resistor and capacitor are determined
empirically to minimize overshoot while maximizing unity-gain
bandwidth. Table I shows a few sample snubber networks for
large load capacitors:
Table I. Snubber Networks for Large Capacitive Loads
Obviously, higher load capacitance will also reduce the unitygain bandwidth of the device. Figure 37 shows a plot of unitygain bandwidth versus capacitive load. The snubber network
will not provide any increase in bandwidth, but it will substantially reduce ringing and overshoot, as shown in the difference
between Figures 35 and 36.
10
9
8
7
6
5
4
BANDWIDTH – MHz
3
2
1
0
10pF10nF100pF1nF
Figure 37. Unity Gain Bandwidth vs. C
C
LOAD
LOAD
Total Harmonic Distortion and Crosstalk
The OPx62 device family offers low total harmonic distortion.
This makes it an excellent device choice for audio applications.
Figure 38 shows a graph of THD plus noise figures at 0.001%
for the OP462.
Figure 39 shows a graph of the worst case crosstalk between two
amplifiers in the OP462 device. A 1 V rms signal is applied to
one amplifier while measuring the output of an adjacent amplifier. Both amplifiers are configured for unity gain and supplied
with ±2.5 V.
REV. C
–11–
Page 12
OP162/OP262/OP462
0.010
VS = ⴞ2.5V
A
= 1
V
= 1.0V rms
V
IN
= 10k⍀
R
L
BANDWIDTH:
<10Hz TO 22kHz
0.001
THD+N – %
0.0001
2010k1001k
FREQUENCY – Hz
20k
Figure 38. THD+N vs. Frequency Graph
–40
AV = 1
–50
= 1.0V rms
V
IN
(0dBV)
= 10k⍀
R
L
= ⴞ2.5V
V
S
2010k1001k
FREQUENCY – Hz
20k
–100
XTALK – dBV
–110
–120
–130
–140
–60
–70
–80
–90
Figure 39. Crosstalk vs. Frequency Graph
PCB Layout Considerations
Because the OP162/OP262/OP462 can provide gain at high
frequency, careful attention to board layout and component
selection is recommended. As with any high speed application,
a good ground plane is essential to achieve the optimum performance. This can significantly reduce the undesirable effects of
ground loops and I×R losses by providing a low impedance reference point. Best results are obtained with a multilayer board
design with one layer assigned to ground plane.
Chip capacitors should be used for supply bypassing, with one
end of the capacitor connected to the ground plane and the
other end connected within 1/8 inch of each power pin. An
additional large tantalum electrolytic capacitor (4.7 µF–10 µF)
should be connected in parallel. This capacitor does not need to
be placed as close to the supply pins, as it is to provide current
for fast large-signal changes at the device’s output.
APPLICATION CIRCUITS
Single Supply Stereo Headphone Driver
Figure 40 shows a stereo headphone output amplifier that can
be run from a single +5 V supply. The reference voltage is
derived by dividing the supply voltage down with two 100 kΩ
resistors. A 10 µF capacitor prevents power supply noise from
contaminating the audio signal and establishes an ac ground for
the volume control potentiometers.
The audio signal is ac coupled to each noninverting input
through a 10 µF capacitor. The gain of the amplifier is controlled by the feedback resistors and is: (R2/R1) + 1. For this
example, the gain is 6. By removing R1 altogether, the amplifier
would have unity gain. A 169 Ω resistor is placed at the output
in the feedback network to short-circuit protect the output of
the device. This would prevent any damage to the device from
occurring if the headphone output became shorted. A 270 µF
capacitor is used at the output to couple the amplifier to the
headphone. This value is much larger than that used for the
input because of the low impedance of headphones, which can
range from 32 Ω to 600 Ω or more.
LEFT IN
RIGHT IN
5V
10F
10k⍀
100k⍀
10k⍀
10F
R1 = 10k⍀
10F
L VOLUME
CONTROL
R VOLUME
CONTROL
R1 = 10k⍀
OP262-A
100k⍀
10F
OP262-B
10F
R2
= 50k⍀
5V
5V
R2 = 50k⍀
169⍀
169⍀
270F
47k⍀
270F
47k⍀
HEADPHONE
LEFT
HEADPHONE
RIGHT
Figure 40. Headphone Output Amplifier
Instrumentation Amplifier
Because of its high speed, low offset voltages and low noise
characteristics, the OP162/OP262/OP462 can be used in a wide
variety of high speed applications, including a precision instrumentation amplifier. Figure 41 shows an example of such an
application.
–V
IN
+V
IN
OP462-A
R
G
OP462-B
1k⍀
1k⍀
10k⍀
10k⍀
2k⍀
2k⍀
2k⍀
OP462-COP462-D
1.9k⍀
200⍀
10 TURN
(OPTIONAL)
OUTPUT
Figure 41. A High Speed Instrumentation Amplifier
–12–
REV. C
Page 13
OP162/OP262/OP462
The differential gain of the circuit is determined by RG, where:
= 1 +
2
R
G
A
DIFF
with the RG resistor value in kΩ. Removing RG will set the circuit gain to unity.
The fourth op amp, OP462-D, is optional and is used to improve CMRR by reducing any input capacitance to the amplifier. By shielding the input signal leads and driving the shield
with the common-mode voltage, input capacitance is eliminated
at common-mode voltages. This voltage is derived from the
midpoint of the outputs of OP462-A and OP462-B by using two
10 kΩ resistors followed by OP462-D as a unity gain buffer.
It is important to use 1% or better tolerance components for the
2 kΩ resistors, as the common-mode rejection is dependent on
their ratios being exact. A potentiometer should also be connected in series with the OP462-C noninverting input resistor to
ground to optimize common-mode rejection.
The circuit in Figure 41 was implemented to test its settling
time. The instrumentation amp was powered with ±5 V, so the
input step voltage went from –5 V to +4 V to keep the OP462
within its input range. Therefore, the 0.05% settling range is
when the output is within 4.5 mV. Figure 42 shows the positive
slope settling time to be 1.8 µs, and Figure 43 shows a settling
time of 3.9 µs for the negative slope.
5mV
100
90
10
0%
2V
1s
Figure 42. Positive Slope Settling Time
5mV
5mV
100
100
90
90
2V
Direct Access Arrangement
Figure 44 shows a schematic for a +5 V single supply transmit/
receive telephone line interface for 600 Ω transmission systems.
It allows full duplex transmission of signals on a transformer
coupled 600 Ω line. Amplifier A1 provides gain that can be
adjusted to meet the modem output drive requirements. Both
A1 and A2 are configured so as to apply the largest possible
differential signal to the transformer. The largest signal available
on a single +5 V supply is approximately 4.0 V p-p into a 600 Ω
transmission system. Amplifier A3 is configured as a difference
amplifier to extract the receive information from the transmission line for amplification by A4. A3 also prevents the transmit
signal from interfering with the receive signal. The gain of A4
can be adjusted in the same manner as A1’s to meet the modem’s
input signal requirements. Standard resistor values permit the
use of SIP (Single In-line Package) format resistor arrays. Couple
this with the OP462 14-lead SOIC or TSSOP package and this
circuit can offer a compact solution.
P1
TX GAIN
TO TELEPHONE
LINE
1:1
Z
O
600⍀
T1
MIDCOM
671-8005
A1, A2 = 1/2 AD8532
A3, A4 = 1/2 AD8532
6.2V
6.2V
10k⍀
R11
R3
360⍀
R9
10k⍀
R12
10k⍀
2
3
ADJUST
R5
10k⍀
R6
10k⍀
R10
10k⍀
A3
2k⍀
1
7
1
9.09k⍀
A1
A2
R13
10k⍀
R2
2
3
6
5
10k⍀
R14
14.3k⍀
6
A4
5
R1
C1
0.1F
5V DC
10F
P2
RX GAIN
ADJUST
2k⍀
7
C2
0.1F
TRANSMIT
R7
10k⍀
R8
10k⍀
RECEIVE
TXA
RXA
Figure 44. A Single-Supply Direct Access Arrangement for
Modems
REV. C
10
10
0%
0%
1µs
1s
Figure 43. Negative Slope Settling Time
–13–
Page 14
OP162/OP262/OP462
Spice Macro-Model
* OP162/OP262/OP462 SPICE Macro-model
* 7/96, Ver. 1
* Troy Murphy / ADSC
*
* Copyright 1996 by Analog Devices
*
* Refer to “README.DOC” file for License Statement. Use of this model
* indicates your acceptance of the terms and provisions in the License
* Statement
*
* Node Assignments
*noninverting input
*|inverting input
*|| positive supply
*|| | negative supply
*|| | | output
*|| | | |
*|| | | |
.SUBCKT OP162 12995045
*
*INPUT STAGE
*
Q1573PIX 5
Q2624PIX 5
Ios121.25E-9
I19915 85E-6
EOS 71POLY(1) (14, 20)45E-6 1
RC1 550 3.035E+3
RC2 650 3.035E+3
RE1 315 607
RE2 415 607
C156600E-15
D138DX
D249DX
V1998DC 1
V2999DC 1
*
* 1st GAIN STAGE
*
EREF 98 0(20, 0) 1
G198 10 (5, 6)10.5
R110 98 1
C210 98 3.3E-9
*
* COMMON-MODE STAGE WITH ZERO AT 4kHz
*
ECM 13 98 POLY (2)(1, 98) (2, 98) 00.5 0.5
R213 14 1E+6
R314 98 70
C313 14 80E-12
*
* POLE AT 1.5MHz, ZERO AT 3MHz
*
G2 21 98 (10, 98).588E-6
R421 98 1.7E6
R521 22 1.7E6
C422 98 31.21E-15
*
* POLE AT 6MHz, ZERO AT 3MHz
*