Dual/Quad Rail-to-Rail
Operational Amplifiers
OP295/OP495
Rev. G
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FEATURES
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
APPLICATIONS
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.
PIN CONFIGURATIONS
OUT A 1
–IN A 2
+IN A 3
V– 4
V+8
OUT B7
–IN B
6
+IN B
5
OP295
TOP VIEW
(Not to Scale)
00331-001
Figure 1. 8-Lead Narrow-Body SOIC_N
S Suffix (R-8)
OUT A
1
–IN A
2
+IN A
3
V–
4
V+
8
OUT B
7
–IN B
6
+IN B
5
OP295
0
0331-002
Figure 2. 8-Lead PDIP
P Suffix (N-8)
OUT A
1
–IN A
2
+IN A
3
V+
4
OUT D
14
–IN D
13
+IN D
12
V–
11
+IN B
5
–IN B
6
OUT B
7
+IN C
10
–IN C
9
OUT C
8
OP495
00331-003
Figure 3. 14-Lead PDIP
P Suffix (N-14)
OUT A 1
–IN A 2
+IN A 3
V+ 4
OUT D
16
–IN D15
+IN D14
V–
13
+IN B 5+IN C12
–IN B 6–IN C
11
OUT B 7OUT C10
NC 8NC9
NC = NO CONNECT
OP495
TOP VIEW
(Not to Scale)
00331-004
Figure 4. 16-Lead SOIC_W
S Suffix (RW-16)
The OP295 and OP495 are specified over the extended indus-
trial (−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.
OP295/OP495
Rev. G | Page 2 of 16
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Pin Configurations ........................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Electrical Characteristics ............................................................. 3
Absolute Maximum Ratings ............................................................ 5
Thermal Resistance ...................................................................... 5
ESD Caution .................................................................................. 5
Typical Performance Characteristics ............................................. 6
Applications ....................................................................................... 9
Rail-to-Rail Application Information ........................................ 9
Low Drop-Out Reference ............................................................ 9
Low Noise, Single-Supply Preamplifier ..................................... 9
Driving Heavy Loads ................................................................. 10
Direct Access Arrangement ...................................................... 10
Single-Supply Instrumentation Amplifier .............................. 10
Single-Supply RTD Thermometer Amplifier ......................... 11
Cold Junction Compensated, Battery-Powered
Thermocouple Amplifier .......................................................... 11
5 V Only, 12-Bit DAC That Swings 0 V to 4.095 V .................... 11
4 mA to 20 mA Current-Loop Transmitter ............................ 12
3 V Low Dropout Linear Voltage Regulator ............................. 12
Low Dropout, 500 mA Voltage Regulator with Foldback
Current Limiting ........................................................................ 12
Square Wave Oscillator .............................................................. 13
Single-Supply Differential Speaker Driver .............................. 13
High Accuracy, Single-Supply, Low Power Comparator ...... 13
Outline Dimensions ....................................................................... 14
Ordering Guide .......................................................................... 16
REVISION HISTORY
8/09—Rev. F to Rev. G
Added Figure 18 ................................................................................ 8
Updated Outline Dimensions ....................................................... 17
3/08—Rev. E to Rev. F
Changes to Offset Voltage Unit in Table 1 .................................... 3
Updated Outline Dimensions ....................................................... 14
Changes to Ordering Guide .......................................................... 16
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
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
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
OP295/OP495
Rev. G | Page 3 of 16
SPECIFICATIONS
ELECTRICAL CHARACTERISTICS
VS = 5.0 V, VCM = 2.5 V, TA = 25°C, unless otherwise noted.
Table 1.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 30 300 µV
−40°C ≤ TA ≤ +125°C 800 µV
Input Bias Current IB 8 20 nA
−40°C ≤ TA ≤ +125°C 30 nA
Input Offset Current IOS ±1 ±3 nA
−40°C ≤ TA ≤ +125°C ±5 nA
Input Voltage Range VCM 0 4.0 V
Common-Mode Rejection Ratio CMRR 0 V ≤ VCM ≤ 4.0 V, −40°C ≤ TA ≤ +125°C 90 110 dB
Large Signal Voltage Gain AVO R
L = 10 kΩ, 0.005 ≤ VOUT ≤ 4.0 V 1000 10,000 V/mV
R
L = 10 kΩ, −40°C ≤ TA ≤ +125°C 500 V/mV
Offset Voltage Drift ∆VOS/∆T 1 5 µV/°C
OUTPUT CHARACTERISTICS
Output Voltage Swing High VOH R
L = 100 kΩ to GND 4.98 5.0 V
R
L = 10 kΩ to GND 4.90 4.94 V
I
OUT = 1 mA, −40°C ≤ TA ≤ +125°C 4.7 V
Output Voltage Swing Low VOL R
L = 100 kΩ to GND 0.7 2 mV
R
L = 10 kΩ to GND 0.7 2 mV
I
OUT = 1 mA, −40°C ≤ TA ≤ +125°C 90 mV
Output Current IOUT ±11 ±18 mA
POWER SUPPLY
Power Supply Rejection Ratio PSRR ±1.5 V ≤ VS ≤ ±15 V 90 110 dB
±1.5 V ≤ VS ≤ ±15 V, –40°C ≤ TA ≤ +125°C 85 dB
Supply Current per Amplifier ISY V
OUT = 2.5 V, RL = ∞, −40°C ≤ TA ≤ +125°C 150 µA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 10 kΩ 0.03 V/µs
Gain Bandwidth Product GBP 75 kHz
Phase Margin θO 86 Degrees
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz 1.5 µV p-p
Voltage Noise Density en f = 1 kHz 51 nV/√Hz
Current Noise Density in f = 1 kHz <0.1 pA/√Hz
VS = 3.0 V, VCM = 1.5 V, TA = 25°C, unless otherwise noted.
Table 2.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 100 500 µV
Input Bias Current IB 8 20 nA
Input Offset Current IOS ±1 ±3 nA
Input Voltage Range VCM 0 2.0 V
Common-Mode Rejection Ration CMRR 0 V ≤ VCM ≤ 2.0 V, −40°C ≤ TA ≤ +125°C 90 110 dB
Large Signal Voltage Gain AVO R
L = 10 kΩ 750 V/mV
Offset Voltage Drift VOS/T 1 µV/°C
OP295/OP495
Rev. G | Page 4 of 16
Parameter Symbol Conditions Min Typ Max Unit
OUTPUT CHARACTERISTICS
Output Voltage Swing High VOH R
L = 10 kΩ to GND 2.9 V
Output Voltage Swing Low VOL R
L = 10 kΩ to GND 0.7 2 mV
POWER SUPPLY
Power Supply Rejection Ratio PSRR ±1.5 V ≤ VS ≤ ±15 V 90 110 dB
±1.5 V ≤ VS ≤ ±15 V, −40°C ≤ TA ≤ +125°C 85 dB
Supply Current per Amplifier ISY V
OUT = 1.5 V, RL = ∞, −40°C ≤ TA ≤ +125°C 150 µA
DYNAMIC PERFORMANCE
Slew Rate SR RL = 10 kΩ 0.03 V/µs
Gain Bandwidth Product GBP 75 kHz
Phase Margin θO 85 Degrees
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz 1.6 µV p-p
Voltage Noise Density en f = 1 kHz 53 nV/√Hz
Current Noise Density in f = 1 kHz <0.1 pA/√Hz
VS = ±15.0 V, TA = 25°C, unless otherwise noted.
Table 3.
Parameter Symbol Conditions Min Typ Max Unit
INPUT CHARACTERISTICS
Offset Voltage VOS 300 500 µV
−40°C ≤ TA ≤ +125°C 800 µV
Input Bias Current IB V
CM = 0 V 7 20 nA
V
CM = 0 V, −40°C ≤ TA ≤ +125°C 30 nA
Input Offset Current IOS V
CM = 0 V ±1 ±3 nA
V
CM = 0 V, −40°C ≤ TA ≤ +125°C ±5 nA
Input Voltage Range VCM −15 +13.5 V
Common-Mode Rejection Ratio CMRR −15.0 V ≤ VCM ≤ +13.5 V, −40°C ≤ TA ≤ +125°C 90 110 dB
Large Signal Voltage Gain AVO R
L = 10 kΩ 1000 4000 V/mV
Offset Voltage Drift ∆VOS/∆T 1 µV/°C
OUTPUT CHARACTERISTICS
Output Voltage Swing High VOH R
L = 100 kΩ to GND 14.95 V
R
L = 10 kΩ to GND 14.80 V
Output Voltage Swing Low VOL R
L = 100 kΩ to GND −14.95 V
R
L = 10 kΩ to GND −14.85 V
Output Current IOUT ±15 ±25 mA
POWER SUPPLY
Power Supply Rejection Ratio PSRR VS = ±1.5 V to ±15 V 90 110 dB
V
S = ±1.5 V to ±15 V, −40°C ≤ TA ≤ +125°C 85 dB
Supply Current per Amplifier ISY V
O = 0 V, RL = ∞, VS = ±18 V, −40°C ≤ TA ≤ +125°C 175 µA
Supply Voltage Range VS 3 (± 1.5) 36 (± 18) V
DYNAMIC PERFORMANCE
Slew Rate SR RL = 10 kΩ 0.03 V/µs
Gain Bandwidth Product GBP 85 kHz
Phase Margin θO 83 Degrees
NOISE PERFORMANCE
Voltage Noise en p-p 0.1 Hz to 10 Hz 1.25 µV p-p
Voltage Noise Density en f = 1 kHz 45 nV/√Hz
Current Noise Density in f = 1 kHz <0.1 pA/√Hz
OP295/OP495
Rev. G | Page 5 of 16
ABSOLUTE MAXIMUM RATINGS
THERMAL RESISTANCE
Table 4.
Parameter1 Rating
Supply Voltage ±18 V
Input Voltage ±18 V
Differential Input Voltage2 36 V
Output Short-Circuit Duration Indefinite
Storage Temperature Range
P, S Packages −65°C to +150°C
Operating Temperature Range
OP295G, OP495G –40°C to +125°C
Junction Temperature Range
P, S Packages –65°C to +150°C
Lead Temperature (Soldering, 60 sec) 300°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.
Table 5. Thermal Resistance
Package Type θJA θ
JC Unit
8-Lead PDIP (N-8) 103 43 °C/W
8-Lead SOIC_N (R-8) 158 43 °C/W
14-Lead PDIP (N-14) 83 39 °C/W
16-Lead SOIC_W (RW-16) 98 30 °C/W
ESD CAUTION
1 Absolute maximum ratings apply to packaged parts, unless otherwise noted.
2 For supply voltages less than ±18 V, the absolute maximum input voltage is
equal to the supply voltage.
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.
OP295/OP495
Rev. G | Page 6 of 16
TYPICAL PERFORMANCE CHARACTERISTICS
SUPPLY CURRENT (µA)
140
20
100
80
40
–25
60
–50
120
100
7550250
TEMPERATURE (°C)
V
S
= 36V
V
S
=5V
V
S
=3V
00331-005
Figure 5. Supply Current Per Amplifier vs. Temperature
15.2
–15.2
100
–14.6
–15.0
–25
–14.8
–50
14.2
–14.4
14.4
14.6
14.8
15.0
7550250
– OUTPUT SWING (V) + OUTPUT SWING (V)
V
S
= ±15V R
L
= 100kΩ
R
L
= 10kΩ
R
L
=2kΩ
R
L
= 100kΩ
R
L
=2kΩ
TEMPERATURE (°C)
R
L
= 10kΩ
0
0331-006
Figure 6. Output Voltage Swing vs. Temperature
3.1
2.5
100
2.8
2.6
–25
2.7
–50
3.0
2.9
7550250
TEMPERATURE (°C)
OUTPUT VOLTAGE SWING (V)
VS=3V
RL=2kΩ
RL= 10kΩ
RL= 100kΩ
00331-007
Figure 7. Output Voltage Swing vs. Temperature
200
0
250
50
25
–200–250
100
75
125
150
175
200150100500–50–100–150
UNITS
INPUT OFFSET VOLTAGE (µV)
VS=5V
TA= 25°C
BASED ON 600 OP AMPS
0
0331-008
Figure 8. OP295 Input Offset (VOS) Distribution
UNITS
250
0
3.2
75
25
0.4
50
0
150
100
125
175
200
225
2.82.42.01.61.20.8
TCVOS (µV/°C)
VS=5V
–40°C ≤TA≤+85°C
BASED ON 600 OP AMPS
00331-009
Figure 9. OP295 TCVOS Distribution
5.1
4.5
100
4.8
4.6
–25
4.7
–50
5.0
4.9
7550250
OUTPUT VOLTAGE SWING (V)
V
S
=5V
TEMPERATURE (°C)
R
L
= 100kΩ
R
L
=10kΩ
R
L
=2kΩ
00331-010
Figure 10. Output Voltage Swing vs. Temperature
OP295/OP495
Rev. G | Page 7 of 16
500
0
300
150
50
–50
100
–100
300
200
250
350
400
450
250200150100500
UNITS
VS=5V
TA=25°C
BASED ON 1200 OP AMPS
INPUT OFFSET VOLTAGE (µV)
00331-011
Figure 11. OP495 Input Offset (VOS) Distribution
450
400
350
300
250
200
150
100
50
UNITS
500
0
3.20.4022.42.01.61.20.8 .8
T
C
V
OS
(µV/°C)
V
S
=5V
–40°C ≤T
A
≤+85°C
BASED ON 1200 OP AMPS
00331-012
Figure 12. OP495 TCVOS Distribution
00331-033
20
0
100
12
4
–25
8
–50
16
7550250
INPUT BIAS CURRENT (nA)
TEMPERATURE (°C)
VS=5V
Figure 13. Input Bias Current vs. Temperature
TEMPERATURE (°C)
40
0
100
10
5
–25–50
20
15
25
30
35
7550250
OUTPUT CURRENT (mA)
VS= ±15V
VS=+5V
SOURCE
SINK
SOURCE
SINK
00331-013
Figure 14. Output Current vs. Temperature
100
10
1
TEMPERATURE (°C)
OPEN-LOOP GAIN (V/µV)
V
S
= ±15V
V
O
= ±10V
R
L
=2kΩ
R
L
= 10kΩ
R
L
= 100kΩ
–50 –25 0 25 50 75 100
0
0331-014
Figure 15. Open-Loop Gain vs. Temperature
12
0
100
6
2
–25
4
–50
10
8
7550250
V
S
=5V
V
O
=4V
R
L
=2kΩ
R
L
=10kΩ
R
L
=100kΩ
OPEN-LOOP GAIN (V/µV)
TEMPERATURE (°C)
00331-015
Figure 16. Open-Loop Gain vs. Temperature
OP295/OP495
Rev. G | Page 8 of 16
OUTPUT VOLTAGE Δ TO RAIL
LOAD CURRENT
SINK
SOURCE
V
S
=5V
T
A
= 25°C
1V
100µV
100mV
10mV
1mV
1µA 10µA 100µA 1mA 10mA
00331-016
Figure 17. Output Voltage to Supply Rail vs. Load Current
–40
–20
0
20
40
60
80
100
120
–40
–20
0
20
40
60
80
100
120
0.01 0.1 1101001k
MAGNITUDE (dB)
PHASE (°)
FREQUENCY (KHz)
OP295
T
A
= 25°C
V
SY
= ±15V
00331-034
Figure 18. OP295 Gain and Phase vs. Frequency
OP295/OP495
Rev. G | Page 9 of 16
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 common-
mode 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.
LOW DROP-OUT REFERENCE
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 19
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.
4
2
6
–
+
+
1/2
OP295/OP495
V
OUT
=4.5V
5V
5V
16kΩ
10Ω
20kΩ
0.001µF
REF43
1µF TO
10µF
00331-017
Figure 19. 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 character-
istics 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 20 uses the OP295/OP495 rail-to-rail amplifier and a
matched PNP transistor pair—the MAT03—to achieve zero-
in/zero-out single-supply operation with an input voltage noise
of 3.1 nV/√Hz at 100 Hz.
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-to-
rail 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.
1
2
34
8
–
+
+–
26
53
71
Q1 Q2
MAT03
0.1µF
R1
LED
R4R3
OP295/OP495
10µF
R6
10Ω
VOUT
C2
10µF
R5
10kΩ
Q2
2N3906
R7
510Ω
R2
27kΩR8
100Ω
C1
1500pF
VIN
00331-018
Figure 20. Low Noise Single-Supply Preamplifier
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, respect-
ively. 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.
OP295/OP495
Rev. G | Page 10 of 16
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 A of supply current. However, the output swing does not
include the positive rail, and the bandwidth reduces to approxi-
mately 250 Hz.
Table 6. Single-Supply Low Noise Preamp Performance
I
C = 1.85 mA IC = 0.5 mA
R1 270 Ω 1.0 kΩ
R3, R4 200 Ω 910 Ω
en @ 100 Hz 3.15 nV/√Hz 8.6 nV/√Hz
en @ 10 Hz 4.2 nV/√Hz 10.2 nV/√Hz
ISY 4.0 mA 1.3 mA
IB 11 A 3 µA
Bandwidth 1 kHz 1 kHz
Closed-Loop Gain 1000 1000
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 capaci-
tive loads of several hundred picofarads without oscillating.
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.
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 21. 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 22 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.
10kΩ
1.67V
2N2222 2N2222
OUTPUTS
2N2907 2N2907
5
V
10kΩ10kΩ
0≤V
IN
≤2.5V 5kΩ
–
+
–
+
00331-019
Figure 21. H Bridge
10
90
100
0%
2V 2V 1ms
00331-020
Figure 22. H Bridge Outputs
DIRECT ACCESS ARRANGEMENT
The OP295/OP495 can be used in a single-supply direct access
arrangement (DAA), as shown in Figure 23. 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 modi-
fications. 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.
–
+
–
+
2.5V REF
A3
750pF
A1
37.4kΩ
390pF
RxA
TxA
A2
3.3kΩ20kΩ
475Ω
22.1kΩ
20kΩ
20kΩ
20kΩ
20kΩ0.033µF 1:1
–
+
0.0047µF
OP295/
OP495
OP295/
OP495
OP295/
OP495
0.1µF
0.1µF
00331-021
Figure 23. Direct Access Arrangement
SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER
The OP295/OP495 can be configured as a single-supply
instrumentation amplifier, as shown in Figure 24. 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.
OP295/OP495
Rev. G | Page 11 of 16
V+
–
+
–
+
5
3
2
1
6
8
4
7
1
/
2
OP295/
OP495
1/2
OP295/
OP495
+
–
V
IN
V
O
R4
100kΩ
R3
20kΩ
R2
20kΩ
R1
100kΩ
V
REF
R
G
V
O
=
(
5+200kΩ
)
V
IN
+V
REF
R
G
00331-022
Figure 24. Single-Supply Instrumentation Amplifier
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
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 A current to the bridge. The return current drops across
the parallel resistors 6.19 kΩ and 2.55 M, 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 legs of the bridge, thus improving
the accuracy.
The AMP04 amplifies the differential bridge signal and converts
it to a single-ended output. The gain is set by the series resis-
tance of the 332 resistor plus the 50 potentiometer. The
gain scales the output to produce a 4.5 V full scale. The 0.22 F
capacitor to the output provides a 7 Hz low-pass filter to keep
noise at a minimum.
ZERO ADJ
AD589
37.4kΩ
5V
1.235
3
2
4
5
6
8
1
7
5V
AMP04
50Ω
332Ω
0.22µF
V
O
–
+
2 3
1
+–
200Ω
10-TURNS
26.7kΩ
0.5%
26.7kΩ
0.5%
100Ω
RTD
100Ω
0.5%
2
.55MΩ
1%
6.19kΩ
1%
1/2
OP295/
OP495
4.5V = 450°C
0V = 0°C
0
0331-023
Figure 25. Low Power RTD Amplifier
COLD JUNCTION COMPENSATED, BATTERY-
POWERED THERMOCOUPLE AMPLIFIER
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.
AD589
ALUMEL
CHROMEL
AL
CR
1N914
24.9kΩ
1.235
V
9V
1.33MΩ
20kΩ
2
34
8
–
+
–
+
–
+
1
COLD
JUNCTIONS
ISOTHERMAL
BLOCK
K-TYPE
T
HERMOCOUPLE
4
0.7µV/°
C
V
O
5V = 500°C
0V = 0°C
OP295/
OP495
SCALE
ADJUST
7.15kΩ
1%
1.5MΩ
1%
24.9kΩ
1%
475Ω
1%
2.1kΩ
1%
24.3kΩ
1%
4.99kΩ
1%
500Ω
10-TURN
ZERO
ADJUST
00331-024
Figure 26. Battery-Powered, Cold-Junction Compensated
Thermocouple Amplifier
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 tem-
perature 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.
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 A supply current from a 9 V
battery.
5 V ONLY, 12-BIT DAC THAT SWINGS 0 V TO 4.095 V
Figure 27 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.
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.
OP295/OP495
Rev. G | Page 12 of 16
1.23V
AD589
3
LD
2
13
24
1
8
5V
8
4765
5
V
5
V
DIGITAL
CONTROL
TOTAL POWER DISSIPATION = 1.6mW
R1
17.8kΩ
DAC8043
V
DD
R
FB
V
REF
I
OUT
GND CLK SRI
OP295/
OP495
V
O
= (4.096V)
D
4096
R4
100kΩ
R2
41.2kΩ
R3
5kΩ
+
–
0
0331-025
Figure 27. A 5 V 12-Bit DAC with 0 V to 4.095 V Output Swing
4 mA TO 20 mA CURRENT-LOOP TRANSMITTER
Figure 28 shows a self-powered 4 mA 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 mA 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.
4
REF02
GND
100Ω
220Ω
2N1711
1
8
3
24
220pF
SPAN ADJ
NULL ADJ
HP
5082-2800
100kΩ
1%
26
5V
+
–
+
–
R
L
100Ω
12V
TO
36V
4mA
TO
20mA
100Ω
1%
1/2
OP295/
OP495
100kΩ
10-TURN
1.21MΩ
1%
182kΩ
1%
10kΩ
10-TURN
V
IN
0V + 3V
0
0331-026
Figure 28. 4 mA to 20 mA Current Loop Transmitter
3 V LOW DROPOUT LINEAR VOLTAGE REGULATOR
Figure 29 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.
The amplifier servos the output to a constant voltage, which
feeds a portion of the signal to the error amplifier.
Higher output current, to 100 mA, is achievable at a higher
dropout voltage of 3.8 V.
V
IN
5V TO 3.2V
MJE 350
43kΩ
AD589
1.235V
3
2
4
1
8
1000pF
I
L
< 50m
A
V
O
100µF
44.2kΩ
1%
30.9kΩ
1%
1/2
OP295/
OP495
+
–
0
0331-027
+
+
Figure 29. 3 V Low Dropout Voltage Regulator
Figure 30 shows the regulator’s recovery characteristic when its
output underwent a 20 mA to 50 mA step current change.
10
100
0%
90
1ms20mV
2V
50mA
20mA
OUTPUT
STEP
CURRENT
CONTROL
W
AVEFORM
00331-028
Figure 30. Output Step Load Current Recovery
LOW DROPOUT, 500 mA VOLTAGE REGULATOR
WITH FOLDBACK CURRENT LIMITING
Adding a second amplifier in the regulation loop, as shown in
Figure 31, provides an output current monitor as well as
foldback current limiting protection.
IRF9531
G
6V
REF43
2
4
6
2.5V
A2
A1
1
42
3
5
6
7
8
1N4148
I
O
(NORM) = 0.5
A
I
O
(MAX) = 1A
RSENSE
0.1Ω
1/4W
SD 5V V
O
+
–
1/2
OP295/
OP495
1/2
OP295/
OP495
0.01µF
100kΩ
5%
205kΩ
1%
210kΩ
1%
45.3kΩ
1%
45.3kΩ
1%
124kΩ
1%
124kΩ
1%
00331-029
+
–
+
–
Figure 31. Low Dropout, 500 mA Voltage Regulator
with Foldback Current Limiting
OP295/OP495
Rev. G | Page 13 of 16
V
+
100kΩ
100kΩ
58.7kΩ
R
FREQ OUT
4
1
8
3
2
C
1
RC
FOSC = < 350Hz @ V+ = 5V
1/2
OP295/
OP495
+
–
+
00331-030
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, reverse-
biasing 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 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 regula-
tion loop from the circuit. Figure 32. Square Wave Oscillator Has Stable Frequency Regardless of
Supply Changes
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 fold-
back 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.
10kΩ
90.9kΩ
V+
100kΩ
10kΩ
20kΩ20kΩ
V+
SPEAKER
++
1/4
OP295/
OP495
1/4
OP295/
OP495
1/4
OP295/
OP495
V
IN
2.2µF
–
+
–
+
–
+
00331-031
The rail-to-rail swing of the OP295 exacts higher gate drive to
the power MOSFET, providing a fuller enhancement to the tran-
sistor. 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.
Figure 33. Single-Supply Differential Speaker Driver
HIGH ACCURACY, SINGLE-SUPPLY, LOW POWER
COMPARATOR
SQUARE WAVE OSCILLATOR
The OP295/OP495 make accurate open-loop comparators.
With a single 5 V supply, the offset error is less than 300 V.
Figure 34 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.
The circuit in Figure 32 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.
10
100
0%
90
5ms
2V
1V
OUTPUT
INPUT
(5mV OVERDRIVE
@ OP295 INPUT)
00331-032
The constant frequency comes from the fact that the 58.7 k
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.
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 load,
the OP295/OP495 can swing close to 5 V p-p across the load. Figure 34. Open-Loop Comparator Response Time with 5 mV Overdrive
OP295/OP495
Rev. G | Page 14 of 16
OUTLINE DIMENSIONS
COMPLIANT TO JEDEC STANDARDS MS-001
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.
070606-A
0.022 (0.56)
0.018 (0.46)
0.014 (0.36)
SEATING
PLANE
0.015
(0.38)
MIN
0.210 (5.33)
MAX
0.150 (3.81)
0.130 (3.30)
0.115 (2.92)
0.070 (1.78)
0.060 (1.52)
0.045 (1.14)
8
14
5
0.280 (7.11)
0.250 (6.35)
0.240 (6.10)
0.100 (2.54)
BSC
0.400 (10.16)
0.365 (9.27)
0.355 (9.02)
0.060 (1.52)
MAX
0.430 (10.92)
MAX
0.014 (0.36)
0.010 (0.25)
0.008 (0.20)
0.325 (8.26)
0.310 (7.87)
0.300 (7.62)
0.195 (4.95)
0.130 (3.30)
0.115 (2.92)
0.015 (0.38)
GAUGE
PLANE
0.005 (0.13)
MIN
Figure 35. 8-Lead Plastic Dual In-Line Package [PDIP]
(N-8) P Suffix
Dimensions shown in inches and (millimeters)
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.
COMPLIANT TO JEDEC STANDARDS MS-012-A A
012407-A
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
0.50 (0.0196)
0.25 (0.0099) 45°
8°
0°
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
4
1
85
5.00 (0.1968)
4.80 (0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27 (0.0500)
BSC
6.20 (0.2441)
5.80 (0.2284)
0.51 (0.0201)
0.31 (0.0122)
COPLANARITY
0.10
Figure 36. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body (R-8) S Suffix
Dimensions shown in millimeters and (inches)
OP295/OP495
Rev. G | Page 15 of 16
COMPLIANT TO JEDEC STANDARDS MS-001
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.
070606-A
0.022 (0.56)
0.018 (0.46)
0.014 (0.36)
0.150 (3.81)
0.130 (3.30)
0.110 (2.79)
0.070 (1.78)
0.050 (1.27)
0.045 (1.14)
14
17
8
0.100 (2.54)
BSC
0.775 (19.69)
0.750 (19.05)
0.735 (18.67)
0.060 (1.52)
MAX
0.430 (10.92)
MAX
0.014 (0.36)
0.010 (0.25)
0.008 (0.20)
0.325 (8.26)
0.310 (7.87)
0.300 (7.62)
0.015 (0.38)
GAUGE
PLANE
0.210 (5.33)
MAX
SEATING
PLANE
0.015
(0.38)
MIN
0.005 (0.13)
MIN
0.280 (7.11)
0.250 (6.35)
0.240 (6.10)
0.195 (4.95)
0.130 (3.30)
0.115 (2.92)
Figure 37. 14-Lead Plastic Dual In-Line Package [PDIP]
(N-14) P Suffix
Dimensions shown in inches and (millimeters)
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.
COMPLIANT TO JEDEC STANDARDS MS-013- AA
032707-B
10.50 (0.4134)
10.10 (0.3976)
0.30 (0.0118)
0.10 (0.0039)
2.65 (0.1043)
2.35 (0.0925)
10.65 (0.4193)
10.00 (0.3937)
7.60 (0.2992)
7.40 (0.2913)
0.75 (0.0295)
0.25 (0.0098)
45°
1.27 (0.0500)
0.40 (0.0157)
C
OPLANARITY
0.10 0.33 (0.0130)
0.20 (0.0079)
0.51 (0.0201)
0.31 (0.0122)
SEATING
PLANE
8°
0°
16 9
8
1
1.27 (0.0500)
BSC
Figure 38. 16-Lead Standard Small Outline Package [SOIC_W]
Wide Body (RW-16) S Suffix
Dimensions shown in millimeters and (inches)
OP295/OP495
Rev. G | Page 16 of 16
ORDERING GUIDE
Model Temperature Range Package Description Package Option
OP295GP −40°C to +125°C 8-Lead PDIP P-Suffix (N-8)
OP295GPZ1 −40°C to +125°C 8-Lead PDIP P-Suffix (N-8)
OP295GS −40°C to +125°C 8-Lead SOIC_N S-Suffix (R-8)
OP295GS-REEL −40°C to +125°C 8-Lead SOIC_N S-Suffix (R-8)
OP295GS-REEL7 −40°C to +125°C 8-Lead SOIC_N S-Suffix (R-8)
OP295GSZ1 −40°C to +125°C 8-Lead SOIC_N S-Suffix (R-8)
OP295GSZ-REEL1 −40°C to +125°C 8-Lead SOIC_N S-Suffix (R-8)
OP295GSZ-REEL71 −40°C to +125°C 8-Lead SOIC_N S-Suffix (R-8)
OP495GP −40°C to +125°C 14-Lead PDIP P-Suffix (N-14)
OP495GPZ1 −40°C to +125°C 14-Lead PDIP P-Suffix (N-14)
OP495GS −40°C to +125°C 16-Lead SOIC_W S-Suffix (RW-16)
OP495GS-REEL −40°C to +125°C 16-Lead SOIC_W S-Suffix (RW-16)
OP495GSZ1 −40°C to +125°C 16-Lead SOIC_W S-Suffix (RW-16)
OP495GSZ-REEL1 −40°C to +125°C 16-Lead SOIC_W S-Suffix (RW-16)
1 Z = RoHS Compliant Part.
©2009 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D00331-0-8/09(G)
