Datasheet OP295 Datasheet (ANALOG DEVICES)

Dual/Quad Rail-to-Rail

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.

Operational Amplifiers

OP295/OP495

PIN CONFIGURATIONS

OUT A 1

–IN A 2

+IN A

V–

OP295

TOP VIEW

3

(Not to Scale)

4

Figure 1. 8-Lead Narrow-Body SOIC_N

S Suffix (R-8)

1

OUT A

–IN A

+IN A

V–

OP295

2

3

4

Figure 2. 8-Lead PDIP

P Suffix (N-8)

1

OUT A

2

–IN A

+IN A

3

V+

4

OP495

+IN B

5

6

–IN B

7

OUT B

Figure 3. 14-Lead PDIP

P Suffix (N-14)

1

OUT A

–IN A

2

+IN A

3

OP495

4

V+

TOP VIEW

+IN B

–IN B

OUT B

(Not to Scale)

5

6

7

NC

8

NC = NO CONNECT

Figure 4. 16-Lead SOIC_W

S Suffix (RW-16)

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.

16

15

14

13

12

11

10

6

5

14

13

12

11

10

9

8

7

6

5

9

8

V+8

OUT B7

–IN B

+IN B

V+

OUT B

–IN B

+IN B

OUT D

–IN D

+IN D

V–

+IN C

–IN C

OUT C

OUT D

–IN D

+IN D

V–

+IN C

–IN C

OUT C

NC

00331-001

0331-002

00331-003

00331-004

Rev. G

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: [phone] www.analog.com
Fax: [phone] ©2009 Analog Devices, Inc. All rights reserved.

OP295/OP495

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

Rev. G | 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 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
R
Offset Voltage Drift ∆VOS/∆T 1 5 µV/°C

OUTPUT CHARACTERISTICS

Output Voltage Swing High VOH R
R
I
Output Voltage Swing Low VOL R
R
I
Output Current I

±11 ±18 mA

OUT

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

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

V

= 3.0 V, VCM = 1.5 V, TA = 25°C, unless otherwise noted.

S

= 10 kΩ, 0.005 ≤ V

L

= 10 kΩ, −40°C ≤ TA ≤ +125°C 500 V/mV

L

= 100 kΩ to GND 4.98 5.0 V

L

= 10 kΩ to GND 4.90 4.94 V

L

= 1 mA, −40°C ≤ TA ≤ +125°C 4.7 V

OUT

= 100 kΩ to GND 0.7 2 mV

L

= 10 kΩ to GND 0.7 2 mV

L

= 1 mA, −40°C ≤ TA ≤ +125°C 90 mV

OUT

= 2.5 V, RL = ∞, −40°C ≤ TA ≤ +125°C 150 µA

OUT

≤ 4.0 V 1000 10,000 V/mV

OUT

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

= 10 kΩ 750 V/mV

L

Offset Voltage Drift VOS/T 1 µV/°C

Rev. G | Page 3 of 16

OP295/OP495

Parameter Symbol Conditions Min Typ Max Unit

OUTPUT CHARACTERISTICS

Output Voltage Swing High VOH R
Output Voltage Swing Low VOL R

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

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

V

= ±15.0 V, TA = 25°C, unless otherwise noted.

S

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
V
Input Offset Current IOS V
V
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
Offset Voltage Drift ∆VOS/∆T 1 µV/°C

OUTPUT CHARACTERISTICS

Output Voltage Swing High VOH R
R
Output Voltage Swing Low VOL R
R
Output Current I

±15 ±25 mA

OUT

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = ±1.5 V to ±15 V 90 110 dB
V
Supply Current per Amplifier ISY V
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

= 10 kΩ to GND 2.9 V

L

= 10 kΩ to GND 0.7 2 mV

L

= 1.5 V, RL = ∞, −40°C ≤ TA ≤ +125°C 150 µA

OUT

= 0 V 7 20 nA

CM

= 0 V, −40°C ≤ TA ≤ +125°C 30 nA

CM

= 0 V ±1 ±3 nA

CM

= 0 V, −40°C ≤ TA ≤ +125°C ±5 nA

CM

= 10 kΩ 1000 4000 V/mV

L

= 100 kΩ to GND 14.95 V

L

= 10 kΩ to GND 14.80 V

L

= 100 kΩ to GND −14.95 V

L

= 10 kΩ to GND −14.85 V

L

= ±1.5 V to ±15 V, −40°C ≤ TA ≤ +125°C 85 dB

S

= 0 V, RL = ∞, VS = ±18 V, −40°C ≤ TA ≤ +125°C 175 µA

O

Rev. G | Page 4 of 16

OP295/OP495

ABSOLUTE MAXIMUM RATINGS

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

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.

THERMAL RESISTANCE

θJA is specified for worst case mounting conditions; that is, θJA
is specified for device in socket for PDIP; θ

is specified for

JA

device soldered to printed circuit board for SOIC package.

Table 5. Thermal Resistance

Package Type θJA θ

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

Unit

JC

ESD CAUTION

Rev. G | Page 5 of 16

OP295/OP495

TYPICAL PERFORMANCE CHARACTERISTICS

140

120

100

80

60

SUPPLY CURRENT (µA)

40

VS= 36V

VS=5V

VS=3V

200

BASED ON 600 OP AM PS

175

150

125

100

UNITS

75

50

25

VS=5V
T

= 25°C

A

20

–50

–25

TEMPERATURE (°C)

Figure 5. Supply Current Per Amplifier vs. Temperature

– OUTPUT SWING (V) + OUTPUT SWING (V)

15.2

15.0

14.8

14.6

14.4

14.2

–14.4

–14.6

–14.8

–15.0

–15.2

–50

–25

TEMPERATURE (°C)

VS= ±15V RL= 100kΩ

Figure 6. Output Voltage Swing vs. Temperature

3.1
VS=3V

3.0

2.9

7550250

RL= 10kΩ

RL=2kΩ

RL=2kΩ

RL= 10kΩ

RL= 100kΩ

7550250

RL= 100kΩ

RL= 10kΩ

100

100

0

–200–250

00331-005

INPUT OFFSET VOLTAGE (µV)

250

200150100500–50–100–150

0331-008

Figure 8. OP295 Input Offset (VOS) Distribution

250

BASED ON 600 OP AMPS

225

200

175

150

125

UNITS

100

75

50

25

0

0.4

0331-006

0

TCVOS(µV/°C)

VS=5V
–40°C ≤ T

≤ +85°C

A

2.82.42.01.61.20.8

3.2

00331-009

Figure 9. OP295 TCVOS Distribution

5.1
VS=5V

5.0

4.9

RL= 100kΩ

RL=10kΩ

2.8

2.7

OUTPUT VOLTAGE SWING (V)

2.6

2.5
–50

–25

TEMPERATURE (°C)

Figure 7. Output Voltage Swing vs. Temperature

RL=2kΩ

7550250

100

00331-007

Rev. G | Page 6 of 16

4.8

4.7

OUTPUT VOLTAGE SWING (V)

4.6

4.5
–50

–25

TEMPERATURE (°C)

Figure 10. Output Voltage Swing vs. Temperature

RL=2kΩ

7550250

100

00331-010

OP295/OP495

500

BASED ON 1200 OP AMPS

450

400

350

300

250

UNITS

200

150

100

50

0

–50

–100

Figure 11. OP495 Input Offset (V

INPUT OFFSET VOLTAGE (µV)

) Distribution

OS

VS=5V
T

=25°C

A

250200150100500

300

00331-011

40

SINK

SOURCE

SINK

SOURCE

–25–50

TEMPERATURE (°C)

VS= ±15V

VS=+5V

100

7550250

00331-013

35

30

25

20

15

OUTPUT CURRENT ( mA)

10

5

0

Figure 14. Output Current vs. Temperature

500

BASED ON 1200 OP AMPS

450

400

350

300

250

UNITS

200

150

100

50

0

20

=5V

V

S

16

12

8

INPUT BIAS CURRENT (nA)

4

VS=5V
–40°C ≤ T

TCVOS(µV/°C)

Figure 12. OP495 TCVOS Distribution

≤ +85°C

A

100

VS= ±15V

= ±10V

V

O

10

OPEN-LOOP GAIN (V/µV)

3.20.4022.42.01. 61.20. 8 .8

00331-012

1

–50 –25 0 25 50 75 100

Figure 15. Open-Loop Gain vs. Temperature

12

VS=5V
V

=4V

O

10

8

6

4

OPEN-LOOP GAIN (V/µV)

2

TEMPERATURE (°C)

RL= 100kΩ

RL= 10kΩ

RL=2kΩ

0331-014

RL=100kΩ

RL=10kΩ

RL=2kΩ

0

–50

–25

TEMPERATURE (°C)

Figure 13. Input Bias Current vs. Temperature

100

7550250

00331-033

0

–50

–25

TEMPERATURE (°C)

100

7550250

00331-015

Figure 16. Open-Loop Gain vs. Temperature

Rev. G | Page 7 of 16

OP295/OP495

VS=5V
T

= 25°C

A

1V

120

100

120

100

80

80

100mV

10mV

OUTPUT VO LTAGE Δ TO RAIL

1mV

100µV

1µA 10µA 100µA 1mA 10mA

SOURCE

SINK

LOAD CURRENT

Figure 17. Output Voltage to Supply Rail vs. Load Current

60

40

20

MAGNITUDE (dB)

0

OP295

–20

T

= 25°C

A

V

= ±15V

SY

–40

00331-016

0.01

0.1

1101001k

FREQUENCY (KHz )

Figure 18. OP295 Gain and Phase vs. Frequency

60

40

20

0

–20

–40

PHASE (°)

00331-034

Rev. G | 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.

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.

16kΩ

5V

2

REF43

4

20kΩ

6

OP295/OP495

Figure 19. 4.5 V, Low Drop-Out Reference

0.001µF

–

+

1/2

5V

V

=4.5V

10µF

OUT

+

00331-017

10Ω

1µF T O

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 20 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.

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

V

IN

26

R2
27kΩ

R1

Q2

2N3906

MAT03

Q1 Q2

R7

510Ω

C1

1500pF

R8

100Ω

10µF

+–

53

71

2

–

3

+

R4R3

R5

10kΩ

8

1

4

OP295/OP495

C2
10µF

R6

10Ω

V

OUT

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, 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 h

= 165. This leads to bias currents of 11 µA

FE

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 Tab le 6.

00331-018

Rev. G | Page 9 of 16

OP295/OP495

V

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 approxi­mately 250 Hz.

Table 6. Single-Supply Low Noise Preamp Performance

I

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 capaci­tive 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.

0 ≤ VIN≤ 2.5V

5kΩ

1.67V

10kΩ 10kΩ

= 1.85 mA IC = 0.5 mA

C

5

2N2222 2N2222

10kΩ

–

+

2N2907

–

+

OUTPUTS

2N2907

Figure 21. H Bridge

00331-019

100

90

10

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 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

RxA

TxA

2.5V REF

37.4kΩ

0.1µF

0.0047µF

OP295/

A2

OP495

22.1kΩ

0.1µF

OP295/
OP495

20kΩ

750pF

20kΩ

20kΩ

Figure 23. Direct Access Arrangement

3.3kΩ

+

–

–
A3
+

OP295/
OP495

–

A1

+

20kΩ

20kΩ

475Ω

0.033µF

1:1

00331-021

SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER

The OP295/OP495 can be configured as a single-supply
instrumentation amplifier, as shown in Figure 24. For this
example, V
respect to V
includes ground, and the output swings to both rails.

is set equal to V+/2, and VO is measured with

REF

. The input common-mode voltage range

REF

Rev. G | Page 10 of 16

OP295/OP495

V

2

V

T

4

C

1/2

V+

OP295/
OP495

R3

20kΩ

VIN+V

)

5

684

REF

+

–

100kΩ

7

R4

V

O

00331-022

+

3

+

–

2

R2

20kΩ

VO=(5+

1/2

OP295/

OP495

1

R

200kΩ

R

G

G

V

IN

–

R1

100kΩ

REF

Figure 24. Single-Supply Instrumentation Amplifier

Resistor RG sets the gain of the instrumentation amplifier.
Minimum gain is 6 (with no R

). All resistors should be matched

G

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 resis­tance 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.

.55MΩ

1%

200Ω

10-TURNS

26.7kΩ

0.5%

100Ω
RTD

ZERO ADJ

26.7kΩ

100Ω

0.5%

6.19kΩ
1%

0.5%

AD589

1

2 3

+–

1/2

OP295/

OP495

1.235

37.4kΩ

3

2

Figure 25. Low Power RTD Amplifier

5V

7

1

+

AMP04

–

4

8

5

5V

50Ω

332Ω

0.22µF

6

4.5V = 450°C
0V = 0° C

V

O

0331-023

COLD JUNCTION COMPENSATED, BATTERY­POWERED 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.

1.235

24.9kΩ

24.3kΩ
1%

4.99kΩ

1%

500Ω
10-TURN

ZERO
ADJUST

1%

+

9V

–

SCALE

ADJUST

20kΩ

1.33MΩ

8

–

2

5V = 500°C
0V = 0°C

V

O

1

3

+

4

OP295/
OP495

ISOTHERMAL

ALUMEL

–

AL

+

CR

CHROMEL

K-TYPE

HERMOCOUPLE

0.7µV/°

BLOCK

1N914

COLD
JUNCTIONS

AD589

7.15kΩ

1%

1.5MΩ1%24.9kΩ

1%

475Ω1%2.1kΩ

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 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.

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 (I
of the DAC. The V

, which is normally the input, now becomes

REF

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.

OUT

)

00331-024

Rev. G | Page 11 of 16

OP295/OP495

V5V

A

W

A

R1

17.8kΩ

1.23V

3

AD589

TOTAL PO WER DISSIPATION = 1.6mW

I

OUT

GND CLK SRI

5

8

V

DD

DAC8043

4765

V

DIGITAL

CONTROL

R

REF

LD

3

+

2

–

R2

41.2kΩ

R3
5kΩ

5V

VO= (4.096V)

8

1

4

OP295/
OP495

R4

100kΩ

D

4096

2

FB

1

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.

V

0V + 3V

NULL ADJ

182kΩ

1%

100kΩ

10-TURN

1.21MΩ

HP
5082-2800

1%

3

+

2

–

220pF

100kΩ

1%

SPAN ADJ

IN

10kΩ

10-TURN

Figure 28. 4 mA to 20 mA Current Loop Transmitter

+

8

4

1/2

OP295/

OP495

REF02

26

GND

4

5V

100Ω

–

220Ω

1

2N1711

100Ω

1%

4mA

TO

20mA

12V

TO

36V

R

L

100Ω

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.

IL< 50m

MJE 350

+

V

IN

5V TO 3.2V

43kΩ

0331-025

Figure 29. 3 V Low Dropout Voltage Regulator

1

1000pF

8

4

3

+

2

–

AD589

1.235V

44.2kΩ
1%

30.9kΩ
1%

OP295/
OP495

1/2

+

100µF

V

O

0331-027

Figure 30 shows the regulator’s recovery characteristic when its
output underwent a 20 mA to 50 mA step current change.

2V

100

50mA

20mA

90

10

0%

1ms20mV

00331-028

STEP
CURRENT
CONTROL

AVEFORM

OUTPUT

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

0331-026

Figure 31, provides an output current monitor as well as
foldback current limiting protection.

IO(NORM) = 0.5

RSENSE

IO(MAX) = 1A

5

+

6

–

3

+

124kΩ

–

2

0.1Ω
1/4W

205kΩ

210kΩ

1%

1%

45.3kΩ1%45.3kΩ

1%

124kΩ

1%

1%

2.5V

5V V

IRF9531

SD

+

6V

–

100kΩ

G

5%

1N4148

OP295/

OP495

REF43

2

7

1/2

OP295/

OP495

0.01µF

1

1/2

4

8

A2

A1

4

6

Figure 31. Low Dropout, 500 mA Voltage Regulator

with Foldback Current Limiting

O

00331-029

Rev. G | Page 12 of 16

OP295/OP495

V

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  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.

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 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.

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.

+

100kΩ

100kΩ

58.7kΩ

+

C

8

3

+

1

1/2

4

2

–

OP295/
OP495

R

FREQ OUT

1

= < 350Hz @ V+ = 5V

F

OSC

RC

Figure 32. Square Wave Oscillator Has Stable Frequency Regardless of

Supply Changes

90.9kΩ

–

+

100kΩ

–

+

V+

1/4
OP295/
OP495

1/4
OP295/
OP495

SPEAKER

00331-031

V

IN

20kΩ 20kΩ

V+

+

2.2µF

10kΩ

+

10kΩ

–

+

1/4
OP295/
OP495

Figure 33. 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 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.

1V

100

90

INPUT

(5mV OVERDRIVE

@ OP295 INPUT)

OUTPUT

Figure 34. Open-Loop Comparator Response Time with 5 mV Overdrive

10

0%

2V

5ms

00331-030

00331-032

Rev. G | Page 13 of 16

OP295/OP495

OUTLINE DIMENSIONS

0.210 (5.33)

0.150 (3.81)

0.130 (3.30)

0.115 (2.92)

0.022 (0.56)

0.018 (0.46)

0.014 (0.36)

MAX

0.400 (10.16)

0.365 (9.27)

0.355 (9.02)

8

1

0.100 (2.54)
BSC

0.070 (1.78)

0.060 (1.52)

0.045 (1.14)

5

4

0.280 (7.11)

0.250 (6.35)

0.240 (6.10)

0.015
(0.38)
MIN

SEATING
PLANE

0.005 (0.13)
MIN

0.060 (1.52)
MAX

0.015 (0.38)
GAUGE

PLANE

0.325 (8.26)

0.310 (7.87)

0.300 (7.62)

0.430 (10.92)
MAX

0.195 (4.95)

0.130 (3.30)

0.115 (2.92)

0.014 (0.36)

0.010 (0.25)

0.008 (0.20)

CONTROLL ING DIMENS IONS ARE IN INCHES; MILLIMETER DI MENSIONS
(IN PARENTHESES) ARE ROUNDED-OF F INCH EQUI VALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRI ATE FOR USE IN DESIGN.
CORNER LEADS MAY BE CONFIGURED AS WHOL E OR HALF LEADS.

COMPLIANT TO JEDEC STANDARDS MS-001

070606-A

Figure 35. 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)

4.00 (0.1574)

3.80 (0.1497)

0.25 (0.0098)

0.10 (0.0040)

COPLANARITY

0.10

CONTROLL ING DIMENSI ONS ARE IN MILLIMETERS; INCH DI MENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRI ATE FOR USE IN DESIGN.

85

1

1.27 (0.0500)

SEATING

PLANE

COMPLIANT TO JEDEC STANDARDS MS-012-A A

Figure 36. 8-Lead Standard Small Outline Package [SOIC_N]

Dimensions shown in millimeters and (inches)

6.20 (0.2441)

5.80 (0.2284)

4

BSC

1.75 (0.0688)

1.35 (0.0532)

0.51 (0.0201)

0.31 (0.0122)

Narrow Body (R-8) S Suffix

8°
0°

0.25 (0.0098)

0.17 (0.0067)

0.50 (0.0196)

0.25 (0.0099)

1.27 (0.0500)

0.40 (0.0157)

45°

012407-A

Rev. G | Page 14 of 16

OP295/OP495

C

0.210 (5.33)
MAX

0.150 (3.81)

0.130 (3.30)

0.110 (2.79)

0.022 (0.56)

0.018 (0.46)

0.014 (0.36)

0.775 (19.69)

0.750 (19.05)

0.735 (18.67)

14

1

0.100 (2.54)
BSC

0.070 (1.78)

0.050 (1.27)

0.045 (1.14)

CONTROLL ING DIMENS IONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OF F INCH EQUI VALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRI ATE FOR USE IN DESIGN.
CORNER LEADS M AY BE CONFIGURED AS WHOLE OR HAL F LEADS.

8

0.280 (7. 11)

0.250 (6.35)

0.240 (6.10)

7

0.060 (1.52)
MAX

0.015
(0.38)

0.015 (0.38)

MIN

SEATING
PLANE

0.005 (0.13)
MIN

COMPLIANT TO JEDEC STANDARDS MS-001

GAUGE

PLANE

0.325 (8.26)

0.310 (7.87)

0.300 (7.62)

0.430 (10.92)
MAX

0.195 (4.95)

0.130 (3.30)

0.115 (2.92)

0.014 (0.36)

0.010 (0.25)

0.008 (0.20)

070606-A

Figure 37. 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)

BSC

9

7.60 (0.2992)

7.40 (0.2913)

8

10.65 (0.4193)

10.00 (0.3937)

2.65 (0.1043)

2.35 (0.0925)

SEATING
PLANE

8°
0°

0.33 (0.0130)

0.20 (0.0079)

0
0

.

7

.

2

5

(

0

.

5

(

0

.

0

2

9

5

)

45°

0

0

9

8

)

1.27 (0.0500)

0.40 (0.0157)

032707-B

0.30 (0.0 118)

0.10 (0.0039)

OPLANARITY

0.10

16

1

1.27 (0.0500)

0.51 (0.0201)

0.31 (0.0122)

CONTROLL ING DIMENS IONS ARE IN MILLIM ETERS; INCH DI MENSIONS
(IN PARENTHESES) ARE ROUNDED-O FF MIL LIMETE R EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRI ATE FOR USE IN DESIGN.

COMPLIANT TO JEDEC STANDARDS MS-013- AA

Figure 38. 16-Lead Standard Small Outline Package [SOIC_W]

Wide Body (RW-16) S Suffix

Dimensions shown in millimeters and (inches)

Rev. G | Page 15 of 16

OP295/OP495

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)

Rev. G | Page 16 of 16