AD OP295 Dual/quad rail-to-rail operational amplifier Datasheet

Dual/Quad Rail-to-Rail
Operational Amplifiers
OP295/OP495
Battery-operated instrumentation
Servo amplifiers
Actuator drives
Sensor conditioners
Power supply control
GENERAL DESCRIPTION
Rail-to-rail output swing combined with dc accuracy are the
key features of the OP495 quad and OP295 dual CBCMOS
operational amplifiers. By using a bipolar front end, lower noise
and higher accuracy than those of CMOS designs have been
achieved. Both input and output ranges include the negative
supply, providing the user with zero-in/zero-out capability. For
users of 3.3 V systems such as lithium batteries, the OP295/OP495
are specified for 3 V operation.
Maximum offset voltage is specified at 300 μV for 5 V operation,
and the open-loop gain is a minimum of 1000 V/mV. This yields
performance that can be used to implement high accuracy systems,
even in single-supply designs.
The ability to swing rail-to-rail and supply 15 mA to the load
makes the OP295/OP495 ideal drivers for power transistors and
H bridges. This allows designs to achieve higher efficiencies and
to transfer more power to the load than previously possible
without the use of discrete components.
For applications such as transformers that require driving
inductive loads, increases in efficiency are also possible.
Stability while driving capacitive loads is another benefit of this
design over CMOS rail-to-rail amplifiers. This is useful for
driving coax cable or large FET transistors. The OP295/OP495
are stable with loads in excess of 300 pF.
2
+IN A
3
V–
4
OP295
TOP VIEW
(Not to Scale)
8
V+
7
OUT B
6
–IN B
5
+IN B
00331-001
1
–IN A
Figure 1. 8-Lead Narrow-Body SOIC_N
(S Suffix)
OUT A
1
8
V+
–IN A
2
7
OUT B
+IN A
3
6
–IN B
V–
4
5
+IN B
OP295
00331-002
APPLICATIONS
OUT A
Figure 2. 8-Lead PDIP
(P Suffix)
OUT A
1
14
OUT D
–IN A
2
13
–IN D
+IN A
3
12
+IN D
V+
4
11
V–
+IN B
5
10
+IN C
–IN B
6
9
–IN C
OUT B
7
8
OUT C
OP495
00331-003
Rail-to-rail output swing
Single-supply operation: 3 V to 36 V
Low offset voltage: 300 μV
Gain bandwidth product: 75 kHz
High open-loop gain: 1000 V/mV
Unity-gain stable
Low supply current/per amplifier: 150 μA maximum
PIN CONFIGURATIONS
Figure 3. 14-Lead PDIP
(P Suffix)
OUT A
1
16
OUT D
–IN A
2
15
–IN D
+IN A
3
14
+IN D
V+
4
13
V–
+IN B
5
12
+IN C
–IN B
6
11
–IN C
OUT B
7
10
OUT C
NC
8
9
NC
OP495
TOP VIEW
(Not to Scale)
NC = NO CONNECT
00331-004
FEATURES
Figure 4. 16-Lead SOIC_W
(S Suffix)
The OP295 and OP495 are specified over the extended industrial (−40°C to +125°C) temperature range. The OP295 is
available in 8-lead PDIP and 8-lead SOIC_N surface-mount
packages. The OP495 is available in 14-lead PDIP and 16-lead
SOIC_W surface-mount packages.
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.
Trademarks and registered trademarks are the property of their respective owners.
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
©2006 Analog Devices, Inc. All rights reserved.
OP295/OP495
TABLE OF CONTENTS
Features .............................................................................................. 1
Driving Heavy Loads ................................................................. 10
Applications....................................................................................... 1
Direct Access Arrangement ...................................................... 10
General Description ......................................................................... 1
Single-Supply Instrumentation Amplifier .............................. 10
Pin Configurations ........................................................................... 1
Single-Supply RTD Thermometer Amplifier ......................... 11
Revision History ............................................................................... 2
Cold Junction Compensated, Battery-Powered
Thermocouple Amplifier .......................................................... 11
Specifications..................................................................................... 3
Electrical Characteristics............................................................. 3
Absolute Maximum Ratings............................................................ 5
Thermal Resistance ...................................................................... 5
5 V Only, 12-Bit DAC That Swings 0 V to 4.095 V.................... 11
4 to 20 mA Current-Loop Transmitter.................................... 12
3 V Low Dropout Linear Voltage Regulator............................. 12
ESD Caution.................................................................................. 5
Low Dropout, 500 mA Voltage Regulator with Foldback
Current Limiting ........................................................................ 12
Typical Performance Characteristics ............................................. 6
Square Wave Oscillator.............................................................. 13
Applications....................................................................................... 9
Single-Supply Differential Speaker Driver.............................. 13
Rail-to-Rail Application Information........................................ 9
High Accuracy, Single-Supply, Low Power Comparator ...... 13
Low Drop-Out Reference ............................................................ 9
Outline Dimensions ....................................................................... 14
Low Noise, Single-Supply Preamplifier ..................................... 9
Ordering Guide .......................................................................... 16
REVISION HISTORY
5/06—Rev. D to Rev. E
Updated Format..................................................................Universal
Changes to Features.......................................................................... 1
Changes to Pin Connections........................................................... 1
Updated Outline Dimensions ....................................................... 14
Changes to Ordering Guide .......................................................... 15
3/02—Rev. B to Rev. C
Figure changes to Pin Connections ................................................1
Deleted OP295GBC and OP495GBC from Ordering Guide ......3
Deleted Wafer Test Limits Table......................................................3
Changes to Absolute Maximum Ratings........................................4
Deleted Dice Characteristics............................................................4
2/04—Rev. C to Rev. D
Changes to General Description .................................................... 1
Changes to Specifications ................................................................ 2
Changes to Absolute Maximum Ratings ....................................... 4
Changes to Ordering Guide ............................................................ 4
Updated Outline Dimensions ....................................................... 12
Rev. E | Page 2 of 16
OP295/OP495
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
VS = 5.0 V, VCM = 2.5 V, TA = 25°C, unless otherwise noted.
Table 1.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Symbol
Conditions
Min
VOS
Typ
Max
Unit
30
300
800
20
30
±3
±5
4.0
μA
μA
nA
nA
nA
nA
V
dB
V/mV
V/mV
μV/°C
−40°C ≤ TA ≤ +125°C
Input Bias Current
IB
8
−40°C ≤ TA ≤ +125°C
Input Offset Current
IOS
±1
−40°C ≤ TA ≤ +125°C
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
VCM
CMRR
AVO
Offset Voltage Drift
OUTPUT CHARACTERISTICS
Output Voltage Swing High
VOH
Output Voltage Swing Low
VOL
Output Current
POWER SUPPLY
Power Supply Rejection Ratio
IOUT
Supply Current per Amplifier
DYNAMIC PERFORMANCE
Skew Rate
Gain Bandwidth Product
Phase Margin
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
0 V ≤ VCM ≤ 4.0 V, −40°C ≤ TA ≤ +125°C
RL = 10 kΩ, 0.005 ≤ VOUT ≤ 4.0 V
RL = 10 kΩ, −40°C ≤ TA ≤ +125°C
0
90
1000
500
ΔVOS/ΔT
PSRR
ISY
110
10,000
1
RL = 100 kΩ to GND
RL = 10 kΩ to GND
IOUT = 1 mA, −40°C ≤ TA ≤ +125°C
RL = 100 kΩ to GND
RL = 10 kΩ to GND
IOUT = 1 mA, −40°C ≤ TA ≤ +125°C
4.98
4.90
±11
±1.5 V ≤ VS ≤ ±15 V
±1.5 V ≤ VS ≤ ±15 V, –40°C ≤ TA ≤ +125°C
VOUT = 2.5 V, RL = ∞, −40°C ≤ TA ≤ +125°C
90
85
5.0
4.94
4.7
0.7
0.7
90
±18
5
2
2
110
150
V
V
V
mV
mV
mV
mA
dB
dB
μA
SR
GBP
θO
RL = 10 kΩ
0.03
75
86
V/μs
kHz
Degrees
en p-p
en
in
0.1 Hz to 10 Hz
f = 1 kHz
f = 1 kHz
1.5
51
<0.1
μV p-p
nV/√Hz
pA/√Hz
VS = 3.0 V, VCM = 1.5 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Input Bias Current
Input Offset Current
Input Voltage Range
Common-Mode Rejection Ration
Large Signal Voltage Gain
Offset Voltage Drift
Symbol
VOS
IB
IOS
VCM
CMRR
AVO
∆VOS/∆T
Conditions
0 V ≤ VCM ≤ 2.0 V, −40°C ≤ TA ≤ +125°C
RL = 10 kΩ
Rev. E | Page 3 of 16
Min
0
90
Typ
Max
Unit
100
8
±1
500
20
±3
2.0
μV
nA
nA
V
dB
V/mV
μV/°C
110
750
1
OP295/OP495
Parameter
OUTPUT CHARACTERISTICS
Output Voltage Swing High
Output Voltage Swing Low
POWER SUPPLY
Power Supply Rejection Ratio
Symbol
Conditions
Min
VOH
VOL
RL = 10 kΩ to GND
RL = 10 kΩ to GND
2.9
PSRR
90
85
Supply Current per Amplifier
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
Phase Margin
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
ISY
±1.5 V ≤ VS ≤ ±15 V
±1.5 V ≤ VS ≤ ±15 V, −40°C ≤ TA ≤ +125°C
VOUT = 1.5 V, RL = ∞, −40°C ≤ TA ≤ +125°C
Typ
Max
Unit
0.7
2
V
mV
150
dB
dB
μA
110
SR
GBP
θO
RL = 10 kΩ
0.03
75
85
V/μs
kHz
Degrees
en p-p
en
in
0.1 Hz to 10 Hz
f = 1 kHz
f = 1 kHz
1.6
53
<0.1
μV p-p
nV/√Hz
pA/√Hz
VS = ±15.0 V, TA = 25°C, unless otherwise noted.
Table 3.
Parameter
INPUT CHARACTERISTICS
Offset Voltage
Symbol
IB
Input Offset Current
IOS
VCM
CMRR
AVO
ΔVOS/ΔT
VOH
Output Voltage Swing Low
VOL
Output Current
POWER SUPPLY
Power Supply Rejection Ratio
IOUT
Supply Current per Amplifier
Supply Voltage Range
DYNAMIC PERFORMANCE
Slew Rate
Gain Bandwidth Product
Phase Margin
NOISE PERFORMANCE
Voltage Noise
Voltage Noise Density
Current Noise Density
Min
Typ
Max
Unit
300
500
800
20
30
±3
±5
+13.5
110
4000
1
μV
μV
nA
nA
nA
nA
V
dB
V/mV
μV/°C
±15
±25
V
V
V
V
mA
90
85
110
VOS
Input Bias Current
Input Voltage Range
Common-Mode Rejection Ratio
Large Signal Voltage Gain
Offset Voltage Drift
OUTPUT CHARACTERISTICS
Output Voltage Swing High
Conditions
PSRR
ISY
VS
−40°C ≤ TA ≤ +125°C
VCM = 0 V
VCM = 0 V, −40°C ≤ TA ≤ +125°C
VCM = 0 V
VCM = 0 V, −40°C ≤ TA ≤ +125°C
−15.0 V ≤ VCM ≤ +13.5 V, −40°C ≤ TA ≤ +125°C
RL = 10 kΩ
RL = 100 kΩ to GND
RL = 10 kΩ to GND
RL = 100 kΩ to GND
RL = 10 kΩ to GND
VS = ±1.5 V to ±15 V
VS = ±1.5 V to ±15 V, −40°C ≤ TA ≤ +125°C
VO = 0 V, RL = ∞, VS = ±18 V, −40°C ≤ TA ≤ +125°C
7
±1
−15
90
1000
14.95
14.80
−14.95
−14.85
175
36 (± 18)
3 (± 1.5)
dB
dB
μA
V
SR
GBP
θO
RL = 10 kΩ
0.03
85
83
V/μs
kHz
Degrees
en p-p
en
in
0.1 Hz to 10 Hz
f = 1 kHz
f = 1 kHz
1.25
45
<0.1
μV p-p
nV/√Hz
pA/√Hz
Rev. E | Page 4 of 16
OP295/OP495
ABSOLUTE MAXIMUM RATINGS
Table 4.
Parameter1
Supply Voltage
Input Voltage
Differential Input Voltage2
Output Short-Circuit Duration
Storage Temperature Range
P, S Package
Operating Temperature Range
OP295G, OP495G
Junction Temperature Range
P, S Package
Lead Temperature (Soldering, 60 sec)
1
2
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.
Rating
±18 V
±18 V
36 V
Indefinite
−65°C to +150°C
THERMAL RESISTANCE
–40°C to +125°C
θJA is specified for worst case mounting conditions; that is, θJA
is specified for device in socket for PDIP; θJA is specified for
device soldered to printed circuit board for SOIC package.
–65°C to +150°C
300°C
Table 5. Thermal Resistance
Absolute maximum ratings apply to packaged parts, unless otherwise noted.
For supply voltages less than ±18 V, the absolute maximum input voltage is
equal to the supply voltage.
Package Type
8-Lead PDIP (P Suffix)
8-Lead SOIC_N (S Suffix)
14-Lead PDIP (P Suffix)
16-Lead SOIC_W (S Suffix)
θJA
103
158
83
98
ESD 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 this product 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.
Rev. E | Page 5 of 16
θJC
43
43
39
30
Unit
°C/W
°C/W
°C/W
°C/W
OP295/OP495
TYPICAL PERFORMANCE CHARACTERISTICS
140
200
120
125
VS = 5V
80
VS = 3V
100
75
60
50
40
25
50
75
100
TEMPERATURE (°C)
0
–250 –200 –150 –100
250
RL = 100kΩ
BASED ON 600 OP AMPS
100
150
200
250
3.2
VS = 5V
–40°C ≤ TA ≤ +85°C
225
14.8
200
RL = 10kΩ
14.6
175
14.4
RL = 2kΩ
150
UNITS
14.2
125
100
–14.4
–14.6
–14.8
–15.0
RL = 2kΩ
75
RL = 10kΩ
50
25
RL = 100kΩ
–50
–25
0
25
50
TEMPERATURE (°C)
75
100
0
0
0.4
0.8
1.2
1.6
2.0
2.4
2.8
TCVOS (µV/°C)
Figure 9. OP295 TCVOS Distribution
Figure 6. Output Voltage Swing vs. Temperature
5.1
3.1
VS = 3V
VS = 5V
OUTPUT VOLTAGE SWING (V)
3.0
RL = 100kΩ
2.9
RL = 10kΩ
2.8
2.7
RL = 2kΩ
2.6
RL = 100kΩ
4.9
RL = 10kΩ
4.8
4.7
RL = 2kΩ
4.6
–25
0
25
50
75
TEMPERATURE (°C)
100
00331-007
2.5
–50
5.0
4.5
–50
–25
0
25
50
75
TEMPERATURE (°C)
Figure 10. Output Voltage Swing vs. Temperature
Figure 7. Output Voltage Swing vs. Temperature
Rev. E | Page 6 of 16
100
00331-010
–15.2
50
Figure 8. OP295 Input Offset (VOS) Distribution
00331-006
+ OUTPUT SWING (V)
– OUTPUT SWING (V)
VS = ±15V
15.0
0
INPUT OFFSET VOLTAGE (µV)
Figure 5. Supply Current Per Amplifier vs. Temperature
15.2
–50
00331-008
0
00331-005
–25
00331-009
25
20
–50
OUTPUT VOLTAGE SWING (V)
VS = 5V
TA = 25°C
150
VS = 36V
100
UNITS
SUPPLY CURRENT (µA)
BASED ON 600 OP AMPS
175
OP295/OP495
500
BASED ON 1200 OP AMPS
40
VS = 5V
TA = 25°C
450
SOURCE
35
OUTPUT CURRENT (mA)
400
350
250
200
150
100
VS = ±15V
25
SOURCE
20
SINK
15
VS = +5V
10
5
50
–50
0
50
100
150
200
INPUT OFFSET VOLTAGE (µV)
250
300
0
–50
00331-011
0
–100
–25
BASED ON 1200 OP AMPS
50
75
100
Figure 14. Output Current vs. Temperature
100
VS = 5V
–40°C ≤ TA ≤ +85°C
450
25
TEMPERATURE (°C)
Figure 11. OP495 Input Offset (VOS) Distribution
500
0
00331-013
UNITS
300
SINK
30
VS = ±15V
VO = ±10V
OPEN-LOOP GAIN (V/µV)
400
350
UNITS
300
250
200
150
RL = 100kΩ
10
RL = 10kΩ
100
0.4
0.8
1.2
1.6
2.0
2.4
2.8
3.2
TCVOS (µV/°C)
0
25
50
75
100
100
TEMPERATURE (°C)
Figure 15. Open-Loop Gain vs. Temperature
Figure 12. OP495 TCVOS Distribution
20
12
VS = 5V
VO = 4V
VS = 5V
10
OPEN-LOOP GAIN (V/µV)
16
12
8
4
0
–50
8
RL = 100kΩ
6
RL = 10kΩ
4
RL = 2kΩ
2
–25
0
25
50
TEMPERATURE (°C)
75
100
0
–50
00331-033
INPUT BIAS CURRENT (nA)
–25
00331-014
0
1
–50
00331-012
0
00331-015
RL = 2kΩ
50
–25
0
25
50
75
TEMPERATURE (°C)
Figure 16. Open-Loop Gain vs. Temperature
Figure 13. Input Bias Current vs. Temperature
Rev. E | Page 7 of 16
OP295/OP495
1V
100mV
SOURCE
10mV
SINK
1mV
100µV
1µA
10µA
100µA
1mA
LOAD CURRENT
10mA
00331-016
OUTPUT VOLTAGE Δ TO RAIL
VS = 5V
TA = 25°C
Figure 17. Output Voltage to Supply Rail vs. Load Current
Rev. E | Page 8 of 16
OP295/OP495
APPLICATIONS
RAIL-TO-RAIL APPLICATION INFORMATION
The OP295/OP495 have a wide common-mode input range
extending from ground to within about 800 mV of the positive
supply. There is a tendency to use the OP295/OP495 in buffer
applications where the input voltage could exceed the commonmode input range. This can initially appear to work because of
the high input range and rail-to-rail output range. But above the
common-mode input range, the amplifier is, of course, highly
nonlinear. For this reason, there must be some minimal amount
of gain when rail-to-rail output swing is desired. Based on the
input common-mode range, this gain should be at least 1.2.
R5 and R6 set the gain of 1000, making this circuit ideal for
maximizing dynamic range when amplifying low level signals in
single-supply applications. The OP295/OP495 provide rail-torail output swings, allowing this circuit to operate with 0 V to
5 V outputs. Only half of the OP295/OP495 is used, leaving the
other uncommitted op amp for use elsewhere.
0.1µF
LED
3
The OP295/OP495 can be used to gain up a 2.5 V or other low
voltage reference to 4.5 V for use with high resolution ADCs
that operate from 5 V only supplies. The circuit in Figure 18
supplies up to 10 mA. Its no-load drop-out voltage is only
20 mV. This circuit supplies over 3.5 mA with a 5 V supply.
5
Q1
R6
10Ω
6
MAT03 Q2
7
2
–
8
R7
510Ω
R2
27kΩ
–
C2
10µF
VOUT
1
3
C1
1500pF
R8
100Ω
+
4
OP295/OP495
R4
00331-018
R3
R5
10kΩ
0.001µF
5V
Figure 19. Low Noise Single-Supply Preamplifier
5V
2
6
–
+
10Ω
1µF TO
10µF
VOUT = 4.5V
+
1/2
OP295/OP495
00331-017
20kΩ
4
2
1
16kΩ
REF43
10µF
+
Q2
2N3906
VIN
LOW DROP-OUT REFERENCE
R1
Figure 18. 4.5 V, Low Drop-Out Reference
LOW NOISE, SINGLE-SUPPLY PREAMPLIFIER
Most single-supply op amps are designed to draw low supply
current at the expense of having higher voltage noise. This tradeoff
may be necessary because the system must be powered by a
battery. However, this condition is worsened because all circuit
resistances tend to be higher; as a result, in addition to the op
amp’s voltage noise, Johnson noise (resistor thermal noise) is
also a significant contributor to the total noise of the system.
The choice of monolithic op amps that combine the characteristics of low noise and single-supply operation is rather limited.
Most single-supply op amps have noise on the order of 30 nV/√Hz
to 60 nV/√Hz, and single-supply amplifiers with noise below
5 nV/√Hz do not exist.
To achieve both low noise and low supply voltage operation,
discrete designs may provide the best solution. The circuit in
Figure 19 uses the OP295/OP495 rail-to-rail amplifier and a
matched PNP transistor pair—the MAT03—to achieve zeroin/zero-out single-supply operation with an input voltage noise
of 3.1 nV/√Hz at 100 Hz.
The input noise is controlled by the MAT03 transistor pair and
the collector current level. Increasing the collector current
reduces the voltage noise. This particular circuit was tested with
1.85 mA and 0.5 mA of current. Under these two cases, the
input voltage noise was 3.1 nV/√Hz and 10 nV/√Hz, respectively.
The high collector currents do lead to a tradeoff in supply
current, bias current, and current noise. All of these parameters
increase with increasing collector current. For example,
typically the MAT03 has an hFE = 165. This leads to bias
currents of 11 μA and 3 μA, respectively. Based on the high bias
currents, this circuit is best suited for applications with low
source impedance such as magnetic pickups or low impedance
strain gauges. Furthermore, a high source impedance degrades
the noise performance. For example, a 1 kΩ resistor generates
4 nV/√Hz of broadband noise, which is already greater than the
noise of the preamp.
The collector current is set by R1 in combination with the LED
and Q2. The LED is a 1.6 V Zener diode that has a temperature
coefficient close to that of the Q2 base-emitter junction, which
provides a constant 1.0 V drop across R1. With R1 equal to
270 Ω, the tail current is 3.7 mA and the collector current is half
that, or 1.85 mA. The value of R1 can be altered to adjust the
collector current. When R1 is changed, R3 and R4 should also
be adjusted. To maintain a common-mode input range that
includes ground, the collectors of the Q1 and Q2 should not go
above 0.5 V; otherwise, they could saturate. Thus, R3 and R4
must be small enough to prevent this condition. Their values
and the overall performance for two different values of R1 are
summarized in Table 6.
Rev. E | Page 9 of 16
OP295/OP495
Finally, the potentiometer, R8, is needed to adjust the offset
voltage to null it to zero. Similar performance can be obtained
using an OP90 as the output amplifier with a savings of about
185 μA of supply current. However, the output swing does not
include the positive rail, and the bandwidth reduces to approximately 250 Hz.
100
90
Table 6. Single-Supply Low Noise Preamp Performance
IC = 1.85 mA
270 Ω
IC = 0.5 mA
1.0 kΩ
R3, R4
en @ 100 Hz
en @ 10 Hz
ISY
IB
Bandwidth
Closed-Loop Gain
200 Ω
3.15 nV/√Hz
4.2 nV/√Hz
4.0 mA
11 μA
1 kHz
1000
910 Ω
8.6 nV/√Hz
10.2 nV/√Hz
1.3 mA
3 μA
1 kHz
1000
10
0%
2V
00331-020
R1
1ms
2V
Figure 21. H Bridge Outputs
DIRECT ACCESS ARRANGEMENT
DRIVING HEAVY LOADS
The OP295/OP495 are well suited to drive loads by using a
power transistor, Darlington, or FET to increase the current to
the load. The ability to swing to either rail can assure that the
device is turned on hard. This results in more power to the load
and an increase in efficiency over using standard op amps with
their limited output swing. Driving power FETs is also possible
with the OP295/OP495 because of their ability to drive capacitive loads of several hundred picofarads without oscillating.
The OP295/OP495 can be used in a single-supply direct access
arrangement (DAA), as shown in Figure 22. This figure shows
a portion of a typical DM capable of operating from a single 5 V
supply, and it may also work on 3 V supplies with minor modifications. Amplifier A2 and Amplifier A3 are configured so that
the transmit signal, TxA, is inverted by A2 and is not inverted
by A3. This arrangement drives the transformer differentially so
the drive to the transformer is effectively doubled over a single
amplifier arrangement. This application takes advantage of the
ability of the OP295/OP495 to drive capacitive loads and to save
power in single-supply applications.
390pF
Without the addition of external transistors, the OP295/OP495
can drive loads in excess of ±15 mA with ±15 V or +30 V
supplies. This drive capability is somewhat decreased at lower
supply voltages. At ±5 V supplies, the drive current is ±11 mA.
37.4kΩ
0.1µF
RxA
OP295/
OP495
20kΩ
0.0047µF
Driving motors or actuators in two directions in a single-supply
application is often accomplished using an H bridge. The
principle is demonstrated in Figure 20. From a single 5 V
supply, this driver is capable of driving loads from 0.8 V to
4.2 V in both directions. Figure 21 shows the voltages at the
inverting and noninverting outputs of the driver. There is a
small crossover glitch that is frequency-dependent; it does not
cause problems unless used in low distortion applications, such
as audio. If this is used to drive inductive loads, diode clamps
should be added to protect the bridge from inductive kickback.
3.3kΩ
+
A2
20kΩ
475Ω
–
OP295/
OP495
22.1kΩ
0.1µF
TxA
20kΩ
750pF
20kΩ
0.033µF
1:1
2.5V REF
2N2222
OP295/
OP495
–
A3
+
00331-021
20kΩ
5V
2N2222
–
A1
+
Figure 22. Direct Access Arrangement
10kΩ
5kΩ
1.67V
10kΩ
SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER
OUTPUTS
–
+
10kΩ 2N2907
–
+
2N2907
00331-019
0 ≤ VIN ≤ 2.5V
The OP295/OP495 can be configured as a single-supply
instrumentation amplifier, as shown in Figure 23. For this
example, VREF is set equal to V+/2, and VO is measured with
respect to VREF. The input common-mode voltage range
includes ground, and the output swings to both rails.
Figure 20. H Bridge
Rev. E | Page 10 of 16
OP295/OP495
1/2
OP295/
OP495
+
–
3
+
2
–
+ 8
6
– 4
COLD JUNCTION COMPENSATED, BATTERYPOWERED THERMOCOUPLE AMPLIFIER
VO
7
1/2
OP295/
OP495
VIN
5
The 150 μA quiescent current per amplifier consumption of the
OP295/OP495 makes them useful for battery-powered temperature
measuring instruments. The K-type thermocouple terminates
into an isothermal block where the terminated junctions’ ambient
temperatures can be continuously monitored and corrected by
summing an equal but opposite thermal EMF to the amplifier,
thereby canceling the error introduced by the cold junctions.
1
R1
100kΩ
R2
20kΩ
VREF
R3
20kΩ
R4
100kΩ
RG
)
00331-022
(
VO = 5 + 200kΩ VIN + VREF
RG
AD589
1.235V
24.9kΩ
9V
ISOTHERMAL
BLOCK
Figure 23. Single-Supply Instrumentation Amplifier
1N914
Resistor RG sets the gain of the instrumentation amplifier.
Minimum gain is 6 (with no RG). All resistors should be matched
in absolute value as well as temperature coefficient to maximize
common-mode rejection performance and minimize drift. This
instrumentation amplifier can operate from a supply voltage as
low as 3 V.
SINGLE-SUPPLY RTD THERMOMETER AMPLIFIER
ALUMEL
–
AL
1.5MΩ
1%
7.15kΩ
1%
24.3kΩ
1%
24.9kΩ
1%
4.99kΩ
1%
COLD
JUNCTIONS
500Ω
10-TURN
+
CR
CHROMEL
K-TYPE
THERMOCOUPLE
40.7µV/°C
ZERO
ADJUST
475Ω
1%
2.1kΩ
1%
+
–
SCALE
ADJUST
20kΩ
1.33MΩ
2 –
8
3 +
4
1
OP295/
OP495
VO
5V = 500°C
0V = 0°C
00331-024
V+
Figure 25. Battery-Powered, Cold-Junction Compensated Thermocouple
Amplifier
This RTD amplifier takes advantage of the rail-to-rail swing of
the OP295/OP495 to achieve a high bridge voltage in spite of a
low 5 V supply. The OP295/OP495 amplifier servos a constant
200 μA current to the bridge. The return current drops across
the parallel resistors 6.19 kΩ and 2.55 MΩ, developing a voltage
that is servoed to 1.235 V, which is established by the AD589
band gap reference. The 3-wire RTD provides an equal line
resistance drop in both 100 Ω legs of the bridge, thus improving
the accuracy.
To calibrate, immerse the thermocouple measuring junction in
a 0°C ice bath and adjust the 500 Ω zero-adjust potentiometer
to 0 V out. Then immerse the thermocouple in a 250°C temperature bath or oven and adjust the scale-adjust potentiometer
for an output voltage of 2.50 V, which is equivalent to 250°C.
Within this temperature range, the K-type thermocouple is
quite accurate and produces a fairly linear transfer characteristic.
Accuracy of ±3°C is achievable without linearization.
The AMP04 amplifies the differential bridge signal and converts
it to a single-ended output. The gain is set by the series resistance of the 332 Ω resistor plus the 50 Ω potentiometer. The
gain scales the output to produce a 4.5 V full scale. The 0.22 μF
capacitor to the output provides a 7 Hz low-pass filter to keep
noise at a minimum.
Even if the battery voltage is allowed to decay to as low as 7 V,
the rail-to-rail swing allows temperature measurements to 700°C.
However, linearization may be necessary for temperatures above
250°C, where the thermocouple becomes rather nonlinear. The
circuit draws just under 500 μA supply current from a 9 V
battery.
2.55MΩ
1%
50Ω
5V
26.7kΩ
0.5%
100Ω
RTD
5 V ONLY, 12-BIT DAC THAT SWINGS 0 V TO 4.095 V
ZERO ADJ
26.7kΩ
0.5%
7
3
2
1
100Ω
0.5%
Figure 26 shows a complete voltage output DAC with wide
output voltage swing operating off a single 5 V supply. The
serial input, 12-bit DAC is configured as a voltage output device
with the 1.235 V reference feeding the current output pin (IOUT)
of the DAC. The VREF, which is normally the input, now becomes
the output.
332Ω
–
+
2
3
6.19kΩ
AD589
1%
1/2
OP295/
OP495
1.235
37.4kΩ
1
+
8 0.22µF
AMP04
6
VO
5
–
4
4.5V = 450°C
0V = 0°C
5V
00331-023
200Ω
10-TURNS
The output voltage from the DAC is the binary weighted voltage
of the reference, which is gained up by the output amplifier such
that the DAC has a 1 mV per bit transfer function.
Figure 24. Low Power RTD Amplifier
Rev. E | Page 11 of 16
OP295/OP495
5V
DAC8043
IOUT
VREF
1
+
3
VO =
8
D
4096
VIN
5V TO 3.2V
(4.096V)
VO
+
44.2kΩ
1%
8
1
4
7
6
OP295/
OP495
4
5
4
TOTAL POWER DISSIPATION = 1.6mW
43kΩ
Figure 27 shows a self-powered 4 to 20 mA current-loop
transmitter. The entire circuit floats up from the single-supply
(12 V to 36 V) return. The supply current carries the signal
within the 4 to 20 mA range. Thus, the 4 mA establishes the
baseline current budget within which the circuit must operate.
This circuit consumes only 1.4 mA maximum quiescent
current, making 2.6 mA of current available to power additional
signal conditioning circuitry or to power a bridge circuit.
VIN
0V + 3V
10kΩ
10-TURN
100kΩ
10-TURN
1.21MΩ
1%
3
182kΩ
1%
+
–
–
8
1/2
OP295/
OP495
10
0%
20mV
100Ω
12V
TO
36V
2N1711
4mA
TO
20mA
220pF
100kΩ
HP
5082-2800 1%
90
20mA
OUTPUT
220Ω
4
50mA
STEP
CURRENT
CONTROL
WAVEFORM
2
1
2
2V
4
5V
AD589
100
GND
1ms
Figure 29. Output Step Load Current Recovery
LOW DROPOUT, 500 mA VOLTAGE REGULATOR
WITH FOLDBACK CURRENT LIMITING
RL
100Ω
100Ω
1%
00331-026
SPAN ADJ
REF02
1/2
OP295/
OP495
Figure 29 shows the regulator’s recovery characteristic when its
output underwent a 20 mA to 50 mA step current change.
4 TO 20 mA CURRENT-LOOP TRANSMITTER
6
2
Figure 28. 3 V Low Dropout Voltage Regulator
Figure 26. A 5 V 12-Bit DAC with 0 V to 4.095 Output Swing
+
–
1.235V
R3
5kΩ
NULL ADJ
30.9kΩ
1%
1000pF
R4
100kΩ
R2
41.2kΩ
DIGITAL
CONTROL
3
1
00331-025
AD589
–
2
GND CLK SRI LD
+
+
100µF
00331-027
3
RFB 2
VDD
MJE 350
5V
00331-028
1.23V
IL < 50mA
8
R1
17.8kΩ
Figure 27. 4 to 20 mA Current Loop Transmitter
Adding a second amplifier in the regulation loop, as shown in
Figure 30, provides an output current monitor as well as
foldback current limiting protection.
3 V LOW DROPOUT LINEAR VOLTAGE REGULATOR
Figure 28 shows a simple 3 V voltage regulator design. The
regulator can deliver 50 mA load current while allowing a
0.2 V dropout voltage. The OP295/OP495 rail-to-rail output
swing drives the MJE350 pass transistor without requiring
special drive circuitry. At no load, its output can swing less than
the pass transistor’s base-emitter voltage, turning the device
nearly off. At full load, and at low emitter-collector voltages, the
transistor beta tends to decrease. The additional base current is
easily handled by the OP295/OP495 output.
I (NORM) = 0.5A
RSENSE O
IO (MAX) = 1A
0.1Ω
1/4W
5V VO
IRF9531
S
D
+
6V
–
G
45.3kΩ
1%
45.3kΩ
1%
+ 5
A2
7
1/2
OP295/
OP495
– 6
0.01µF
1
1/2
OP295/
OP495
The amplifier servos the output to a constant voltage, which
feeds a portion of the signal to the error amplifier.
2
Higher output current, to 100 mA, is achievable at a higher
dropout voltage of 3.8 V.
205kΩ
1%
8
1N4148
100kΩ
5%
210kΩ
1%
REF43
4
+ 3
124kΩ
A1
1%
4 – 2
6
124kΩ
1%
2.5V
Figure 30. Low Dropout, 500 mA Voltage Regulator
with Foldback Current Limiting
Rev. E | Page 12 of 16
00331-029
5V
OP295/OP495
If the output current greater than 1 A persists, the current limit
loop forces a reduction of current to the load, which causes a
corresponding drop in output voltage. As the output voltage
drops, the current-limit threshold also drops fractionally,
resulting in a decreasing output current as the output voltage
decreases, to the limit of less than 0.2 A at 1 V output. This foldback effect reduces the power dissipation considerably during a
short circuit condition, thus making the power supply far more
forgiving in terms of the thermal design requirements. Small
heat sinking on the power MOSFET can be tolerated.
The rail-to-rail swing of the OP295 exacts higher gate drive to
the power MOSFET, providing a fuller enhancement to the transistor. The regulator exhibits 0.2 V dropout at 500 mA of load
current. At 1 A output, the dropout voltage is typically 5.6 V.
SQUARE WAVE OSCILLATOR
The circuit in Figure 31 is a square wave oscillator (note the
positive feedback). The rail-to-rail swing of the OP295/OP495
helps maintain a constant oscillation frequency even if the supply
voltage varies considerably. Consider a battery-powered system
where the voltages are not regulated and drop over time. The
rail-to-rail swing ensures that the noninverting input sees the
full V+/2, rather than only a fraction of it.
V+
100kΩ
58.7kΩ
3
+
8
2
–
4
FREQ OUT
1
+
FOSC =
1
< 350Hz @ V+ = 5V
RC
00331-030
100kΩ
1/2
OP295/
OP495
R
C
Figure 31. Square Wave Oscillator Has Stable Frequency Regardless of
Supply Changes
90.9kΩ
10kΩ
VIN
+
2.2µF
+
–
V+
+
10kΩ
100kΩ
1/4
OP295/
OP495
SPEAKER
–
–
+
+
V+
20kΩ
20kΩ
1/4
OP295/
OP495
1/4
OP295/
OP495
00331-031
Amplifier A1 provides error amplification for the normal
voltage regulation loop. As long as the output current is less
than 1 A, the output of Amplifier A2 swings to ground, reversebiasing the diode and effectively taking itself out of the circuit.
However, as the output current exceeds 1 A, the voltage that
develops across the 0.1 Ω sense resistor forces the output of
Amplifier A2 to go high, forward-biasing the diode, which in
turn closes the current-limit loop. At this point, the A2’s lower
output resistance dominates the drive to the power MOSFET
transistor, thereby effectively removing the A1 voltage regulation loop from the circuit.
Figure 32. Single-Supply Differential Speaker Driver
HIGH ACCURACY, SINGLE-SUPPLY, LOW POWER
COMPARATOR
The OP295/OP495 make accurate open-loop comparators.
With a single 5 V supply, the offset error is less than 300 μV.
Figure 33 shows the response time of the OP295/OP495 when
operating open-loop with 4 mV overdrive. They exhibit a 4 ms
response time at the rising edge and a 1.5 ms response time at
the falling edge.
1V
100
90
INPUT
(5mV OVERDRIVE
@ OP295 INPUT)
OUTPUT
10
SINGLE-SUPPLY DIFFERENTIAL SPEAKER DRIVER
Connected as a differential speaker driver, the OP295/OP495
can deliver a minimum of 10 mA to the load. With a 600 Ω load,
the OP295/OP495 can swing close to 5 V p-p across the load.
0%
2V
5ms
Figure 33. Open-Loop Comparator Response Time with 5 mV Overdrive
Rev. E | Page 13 of 16
00331-032
The constant frequency comes from the fact that the 58.7 kΩ
feedback sets up Schmitt trigger threshold levels that are directly
proportional to the supply voltage, as are the RC charge voltage
levels. As a result, the RC charge time, and therefore, the frequency,
remain constant independent of supply voltage. The slew rate of
the amplifier limits oscillation frequency to a maximum of about
800 Hz at a 5 V supply.
OP295/OP495
OUTLINE DIMENSIONS
0.400 (10.16)
0.365 (9.27)
0.355 (9.02)
8
5
1
4
0.280 (7.11)
0.250 (6.35)
0.240 (6.10)
0.325 (8.26)
0.310 (7.87)
0.300 (7.62)
PIN 1
0.100 (2.54)
BSC
0.060 (1.52)
MAX
0.210
(5.33)
MAX
0.150 (3.81)
0.130 (3.30)
0.115 (2.92)
0.195 (4.95)
0.130 (3.30)
0.115 (2.92)
0.015
(0.38)
MIN
0.015 (0.38)
GAUGE
PLANE
SEATING
PLANE
0.022 (0.56)
0.018 (0.46)
0.014 (0.36)
0.430 (10.92)
MAX
0.005 (0.13)
MIN
0.014 (0.36)
0.010 (0.25)
0.008 (0.20)
0.070 (1.78)
0.060 (1.52)
0.045 (1.14)
COMPLIANT TO JEDEC STANDARDS MS-001-BA
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS.
Figure 34. 8-Lead Plastic Dual In-Line Package [PDIP]
(N-8) P Suffix
Dimensions shown in inches and (millimeters)
5.00 (0.1968)
4.80 (0.1890)
8
4.00 (0.1574)
3.80 (0.1497) 1
5
1.27 (0.0500)
BSC
0.25 (0.0098)
0.10 (0.0040)
6.20 (0.2440)
4 5.80 (0.2284)
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
COPLANARITY
SEATING 0.31 (0.0122)
0.10
PLANE
0.50 (0.0196)
× 45°
0.25 (0.0099)
8°
0.25 (0.0098) 0° 1.27 (0.0500)
0.40 (0.0157)
0.17 (0.0067)
COMPLIANT TO JEDEC STANDARDS MS-012-AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 35. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body (R-8) S Suffix
Dimensions shown in millimeters and (inches)
Rev. E | Page 14 of 16
OP295/OP495
0.775 (19.69)
0.750 (19.05)
0.735 (18.67)
14
8
1
7
0.280 (7.11)
0.250 (6.35)
0.240 (6.10)
0.325 (8.26)
0.310 (7.87)
0.300 (7.62)
PIN 1
0.100 (2.54)
BSC
0.060 (1.52)
MAX
0.210
(5.33)
MAX
0.195 (4.95)
0.130 (3.30)
0.115 (2.92)
0.015
(0.38)
MIN
0.150 (3.81)
0.130 (3.30)
0.110 (2.79)
0.015 (0.38)
GAUGE
PLANE
SEATING
PLANE
0.022 (0.56)
0.018 (0.46)
0.014 (0.36)
0.430 (10.92)
MAX
0.005 (0.13)
MIN
0.014 (0.36)
0.010 (0.25)
0.008 (0.20)
0.070 (1.78)
0.050 (1.27)
0.045 (1.14)
COMPLIANT TO JEDEC STANDARDS MS-001-AA
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS.
Figure 36. 14-Lead Plastic Dual In-Line Package [PDIP]
(N-14) P Suffix
Dimensions shown in inches and (millimeters)
10.50 (0.4134)
10.10 (0.3976)
9
16
7.60 (0.2992)
7.40 (0.2913)
8
1
1.27 (0.0500)
BSC
2.65 (0.1043)
2.35 (0.0925)
0.30 (0.0118)
0.10 (0.0039)
COPLANARITY
0.10
10.65 (0.4193)
10.00 (0.3937)
0.51 (0.0201)
0.31 (0.0122)
SEATING
PLANE
8°
0.33 (0.0130) 0°
0.20 (0.0079)
0.75 (0.0295)
× 45°
0.25 (0.0098)
1.27 (0.0500)
0.40 (0.0157)
COMPLIANT TO JEDEC STANDARDS MS-013-AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 37. 16-Lead Standard Small Outline Package [SOIC_W]
Wide Body (RW-16) S Suffix
Dimensions shown in millimeters and (inches)
Rev. E | Page 15 of 16
OP295/OP495
ORDERING GUIDE
Model
OP295GP
OP295GPZ 1
OP295GS
OP295GS-REEL
OP295GS-REEL7
OP295GSZ1
OP295GSZ-REEL1
OP295GSZ-REEL71
OP495GP
OP495GPZ1
OP495GS
OP495GS-REEL
OP495GSZ1
OP495GSZ-REEL1
1
Temperature Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Package Description
8-Lead Plastic DIP
8-Lead Plastic DIP
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
8-Lead SOIC_N
14-Lead Plastic DIP
14-Lead Plastic DIP
16-Lead SOIC_W
16-Lead SOIC_W
16-Lead SOIC_W
16-Lead SOIC_W
Z = Pb-free part.
©2006 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
C00331-0-5/06(E)
Rev. E | Page 16 of 16
Package Option
P-Suffix (N-8)
P-Suffix (N-8)
S-Suffix (R-8)
S-Suffix (R-8)
S-Suffix (R-8)
S-Suffix (R-8)
S-Suffix (R-8)
S-Suffix (R-8)
P-Suffix (N-14)
P-Suffix (N-14)
S-Suffix (RW-16)
S-Suffix (RW-16)
S-Suffix (RW-16)
S-Suffix (RW-16)