Datasheet OP295 Datasheet (Analog Devices)

Page 1

Dual/Quad Rail-to-Rail Operational Amplifiers

OP295/OP495

FEATURES Rail-to-Rail Output Swing Single-Supply Operation: 3 V to 36 V Low Offset Voltage: 300 mV Gain Bandwidth Product: 75 kHz High Open-Loop Gain: 1,000 V/mV Unity-Gain Stable Low Supply Current/Per Amplifier: 150 ␮A max

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 that of CMOS designs has been achieved. Both input and output ranges include the negative supply, providing the user zero-in/zero-out capability. For users of 3.3 V systems such as lithium batteries, the OP295/OP495 is 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 an ideal driver 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,

PIN CONNECTIONS

8-Lead Narrow-Body SOIC

(S Suffix)

OUT A

–IN A

+IN A

OP295

V–

V+

OUT B

–IN B

+IN B

14-Lead PDIP

(P Suffix)

OUT A

–IN A

+IN A

+IN B

–IN B

OUT B

V+

OP495

OUT D

–IN D

+IN D

V–

+IN C

–IN C

OUT C

8-Lead Narrow-Body SOIC

(S Suffix)

OUT A

–IN A

+IN A

OP295

V–

V+

OUT B

–IN B

+IN B

14-Lead PDIP

(P Suffix)

OUT D

OUT A

–IN A

+IN A

V+

+IN B

–IN B

OUT B

NC = NO CONNECT

OP495

TOP VIEW

(Not to Scale)

–IN D

+IN D

V–

+IN C

–IN C

OUT C

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 is stable with loads in excess of 300 pF.

The OP295 and OP495 are specified over the extended industrial (–40°C to +125°C) temperature range. OP295s are available in 8-lead plastic DIP plus SOIC-8 surface-mount packages. OP495s are available in 14-lead plastic and SOIC-16 surfacemount packages.

REV. D

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners.

Page 2

OP295/OP495–SPECIFICATIONS

ELECTRICAL CHARACTERISTICS

(@ VS = 5.0 V, VCM = 2.5 V, TA = 25ⴗC, unless otherwise noted.)

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

Input Bias Current I

Input Offset Current I

Input Voltage Range V Common-Mode Rejection Ratio CMRR 0 V ≤ VCM ≤ 4.0 V, –40°C ≤ TA ≤ +125°C90110 dB Large Signal Voltage Gain A

–40°C ≤ TA ≤ +125°C 800 µV

–40°C ≤ TA ≤ +125°C30nA

–40°C ≤ TA ≤ +125°C ±5nA

0 4.0 V

RL = 10 kΩ, 0.005 ≤ V RL = 10 kΩ, –40°C ≤ TA ≤ +125°C 500 V/mV

≤ 4.0 V 1,000 10,000 V/mV

OUT

30 300 µV

820 nA

±1 ±3nA

Offset Voltage Drift ∆VOS/∆T 15 µV/°C

OUTPUT CHARACTERISTICS

Output Voltage Swing High V

Output Voltage Swing Low V

Output Current I

OUT

RL = 100 kΩ to GND 4.98 5.0 V RL = 10 kΩ to GND 4.90 4.94 V I

= 1 mA, –40°C ≤ TA ≤ +125°C 4.7 V

OUT

RL = 100 kΩ to GND 0.7 2 mV RL = 10 kΩ to GND 0.7 2 mV I

= 1 mA, –40°C ≤ TA ≤ +125°C90mV

OUT

±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°C85dB

Supply Current Per Amplifier I

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

OUT

DYNAMIC PERFORMANCE

Skew Rate SR RL = 10 kΩ 0.03 V/µs Gain Bandwidth Product GBP 75 kHz Phase Margin θ

86 Degrees

NOISE PERFORMANCE

Voltage Noise en p-p 0.1 Hz to 10 Hz 1.5 µV p-p Voltage Noise Density e Current Noise Density i

Specifications subject to change without notice.

f = 1 kHz 51 nV/√Hz f = 1 kHz <0.1 pA/√Hz

ELECTRICAL CHARACTERISTICS

(@ VS = 3.0 V, VCM = 1.5 V, TA = 25ⴗC, unless otherwise noted.)

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V Input Bias Current I Input Offset Current I Input Voltage Range V Common-Mode Rejection Ratio CMRR 0 V ≤ VCM ≤ 2.0 V, –40°C ≤ TA ≤ +125°C90110 dB Large Voltage Gain A Offset Voltage Drift ∆VOS/∆T 1 µV/°C

RL = 10 kΩ 750 V/mV

0 2.0 V

100 500 µV 820 nA ±1 ±3nA

OUTPUT CHARACTERISTICS

Output Voltage Swing High V Output Voltage Swing Low V

RL = 10 kΩ to GND 2.9 V RL = 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°C85dB

Supply Current Per Amplifier I

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

OUT

DYNAMIC PERFORMANCE

Slew Rate SR RL = 10 kΩ 0.03 V/µs Gain Bandwidth Product GBP 75 kHz Phase Margin θ

85 Degrees

NOISE PERFORMANCE

Voltage Noise en p-p 0.1 Hz to 10 Hz 1.6 µV p-p Voltage Noise Density e Current Noise Density i

Specifications subject to change without notice.

f = 1 kHz 53 nV/√Hz f = 1 kHz <0.1 pA/√Hz

REV. D–2–

Page 3

OP295/OP495

ELECTRICAL CHARACTERISTICS

(@ VS = ±15.0 V, TA = 25ⴗC, unless otherwise noted.)

Parameter Symbol Conditions Min Typ Max Unit

INPUT CHARACTERISTICS

Offset Voltage V

Input Bias Current I

–40°C ≤ T

VCM = 0 V 7 20 nA

≤ +125°C 800 µV

300 500 µV

VCM = 0 V, –40°C ≤ TA ≤ +125°C30nA

Input Offset Current I

Input Voltage Range V

Common-Mode Rejection Ratio CMRR –15.0 V ≤ V Large Signal Voltage Gain A

VCM = 0 V ±1 ±3nA V

= 0 V, –40°C ≤ TA ≤ +125°C ±5nA

–15 13.5 V

≤ +13.5 V, –40°C ≤ TA ≤ +125°C90 110 dB

RL = 10 kΩ 1,000 4,000 V/mV

Offset Voltage Drift ∆VOS/∆T 1 µV/°C

OUTPUT CHARACTERISTICS

Output Voltage Swing High V

RL = 100 kΩ to GND 14.95 V RL = 10 kΩ to GND 14.80 V

Output Voltage Swing Low V

Output Current I

OUT

RL = 100 kΩ to GND –14.95 V R

= 10 kΩ to GND –14.85 V

±15 ±25 mA

POWER SUPPLY

Power Supply Rejection Ratio PSRR VS = ± 1.5 V to ± 15 V 90 110 dB

VS = ±1.5 V to ±15 V, –40°C ≤ TA ≤ +125°C85 dB

Supply Current I

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

Supply Voltage Range V

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 θ

83 Degrees

NOISE PERFORMANCE

Voltage Noise en p-p 0.1 Hz to 10 Hz 1.25 µV p-p Voltage Noise Density e

Current Noise Density i

Specifications subject to change without notice.

f =1 kHz 45 nV/√Hz f = 1 kHz <0.1 pA/√Hz

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–3–

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OP295/OP495

ABSOLUTE MAXIMUM RATINGS

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V

Input Voltage Differential Input Voltage

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ± 18 V

. . . . . . . . . . . . . . . . . . . . . . . . . 36 V

1, 2

Output Short-Circuit Duration . . . . . . . . . . . . . . . . . Indefinite

Storage Temperature Range

P, S Package . . . . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C

Operating Temperature Range

OP295G, OP495G . . . . . . . . . . . . . . . . . . .–40°C to +125°C

Junction Temperature Range

P, S Package . . . . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C

Lead Temperature Range (Soldering, 60 sec) . . . . . . . . 300°C

ORDERING GUIDE

Temperature Package Package

Model Range Description Option

OP295GP –40°C to +125°C 8-Lead Plastic DIP P-8 (N-8) OP295GS –40°C to +125°C 8-Lead SOIC S-8 (R-8) OP295GS-REEL –40°C to +125°C 8-Lead SOIC S-8 (R-8) OP295GS-REEL7 –40°C to +125°C 8-Lead SOIC S-8 (R-8) OP495GP –40°C to +125°C 14-Lead Plastic DIP P-14 (N-14) OP495GS –40°C to +125°C 16-Lead SOIC S-16 (RW-16) OP495GS-REEL –40°C to +125°C 16-Lead SOIC S-16 (RW-16) OP495GSZ* –40°C to +125°C 16-Lead SOIC S-16 (RW-16) OP495GSZ-REEL7* –40°C to +125°C 16-Lead SOIC S-16 (RW-16)

*Z = Pb-free part.

NOTES

Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; and 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.

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 ␪JA* ␪

Unit

8-Lead Plastic DIP (P) 103 43 °C/W 8-Lead SOIC (S) 158 43 °C/W 14-Lead Plastic DIP (P) 83 39 °C/W 16-Lead SOIC (S) 98 30 °C/W

*␪JA is specified for worst case mounting conditions, i.e., ␪JA is specified for device

in socket for CERDIP, PDIP, and LCC packages; ␪JA is specified for device soldered to printed circuit board for SOIC package.

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the OP295/OP495 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.

Typical Performance Characteristics

140

120

100

SUPPLY CURRENT – ␮A

–50

–25

TEMPERATURE – ⴗC

VS = 36V

VS = 5V

= 3V

7550250

100

TPC 1. Supply Current Per Amplifier vs. Temperature

15.2

15.0

14.8

14.6

14.4

14.2

–14.4

–14.6

–14.8

–15.0

–15.2

– OUTPUT SWING – V + OUTPUT SWING – V

–50

–25

TEMPERATURE –

TPC 2. Output Voltage Swing vs. Temperature

VS = 15V

= 100k⍀

RL = 10k⍀

= 2k⍀

RL = 2k⍀

RL = 10k⍀

RL = 100k⍀

7550250

100

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OP295/OP495

500

300

150

–50

100

–100

300

200

250

350

400

450

250200150100500

INPUT OFFSET VOLTAGE – ␮V

UNITS

VS = 5V T

= 25ⴗC

BASED ON 1200 OP AMPS

500

3.2

150

0.4

100

300

200

250

350

400

450

2.82.42.01.61.20.8

– VOS – ␮V/ⴗC

UNITS

VS = 5V –40ⴗ

TA +85ⴗC

BASED ON 1200 OP AMPS

3.10

VS = 3V

3.00

2.90

2.80

2.70

OUTPUT VOLTAGE SWING – V

2.60

2.50 –50

–25

TEMPERATURE – ⴗC

RL = 100k⍀

RL = 10k⍀

RL = 2k⍀

7550250

100

TPC 3. Output Voltage Swing vs. Temperature

200

BASED ON 600 OP AMPS

175

150

125

100

UNITS

VS = 5V

= 25ⴗC

5.10

VS = 5V

5.00

4.90

4.80

4.70

OUTPUT VOLTAGE SWING – V

4.60

4.50 –50

–25

TEMPERATURE – ⴗC

RL = 100k⍀

RL = 10k⍀

RL = 2k⍀

7550250

100

TPC 6. Output Voltage Swing vs. Temperature

–200–250

TPC 4. OP295 Input Offset (VOS) Distribution

250

BASED ON 600 OP AMPS

225

200

175

150

125

UNITS

100

TPC 5. OP295 TC–VOS Distribution

REV. D

INPUT OFFSET VOLTAGE – ␮V

0.4

– VOS – ␮V/ⴗC

VS = 5V

–40ⴗ

200150100500–50–100–150

TA +85ⴗC

2.82.42.01.61.20.8

250

TPC 7. OP495 Input Offset (VOS) Distribution

3.2

TPC 8. OP495 TC–VOS Distribution

–5–

Page 6

OP295/OP495

VS = 5V

INPUT BIAS CURRENT – nA

–50

–25

TEMPERATURE – ⴗC

7550250

TPC 9. Input Bias Current vs. Temperature

OUTPUT CURRENT – mA

SINK

SOURCE

VS = 15V

SOURCE

SINK

VS = 5V

100

VS = 5V VO = 4V

RL = 100k⍀

OPEN-LOOP GAIN – V/␮V

–50

–25

TEMPERATURE – ⴗC

RL = 10k⍀

RL = 2k⍀

7550250

TPC 12. Open-Loop Gain vs. Temperature

VS = 5V

= 25ⴗC

100mV

OUTPUT VOLTAGE TO RAIL

10mV

1mV

SOURCE

SINK

100

–25–50

TEMPERATURE – ⴗC

7550250

TPC 10. Output Current vs. Temperature

100

VS = 15V V

= 10V

RL = 100k⍀

RL = 10k⍀

RL = 2k⍀

OPEN-LOOP GAIN – V/␮V

–50 25

–25

TEMPERATURE – ⴗC

TPC 11. Open-Loop Gain vs. Temperature

100

100␮V

1␮A10␮A

100␮A

LOAD CURRENT

TPC 13. Output Voltage to Supply Rail vs.

Load Current

10mA1mA

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OP295/OP495

APPLICATIONS Rail-to-Rail Application Information

The OP295/OP495 has 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 may 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, it is always required that there 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 1 will supply up to 10 mA. Its no-load drop-out voltage is only 20 mV. This circuit will supply over 3.5 mA with a 5 V supply.

16k⍀

REF43

20k⍀

OP295/OP495

0.001␮F

1/2

10⍀

V = 4.5V

OUT

1␮F TO

10 ␮F

Figure 1. 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.

In order to achieve both low noise and low supply voltage operation, discrete designs may provide the best solution. The circuit in Figure 2 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 1,000, 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.

0.1␮F

R1LED

2N3906

R2 27k⍀

Q1 Q2

MAT-03

510⍀

1500pF

100⍀

10␮F

10k⍀

OP295/OP495

10⍀

C2 10␮F

OUT

Figure 2. 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 and 3 µA, respectively. Based on the high bias cur- rents, this circuit is best suited for applications with low source impedance such as magnetic pickups or low impedance strain gages. 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 Q2’s 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. Whenever 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 I. Lastly, 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 will not include the positive rail, and the bandwidth will reduce to approximately 250 Hz.

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Page 8

OP295/OP495

Table I. Single-Supply Low Noise Preamp Performance

IC = 1.85 mA IC = 0.5 mA

R1 270 Ω 1.0 kΩ R3, R4 200 Ω 910 Ω

@ 100 Hz 3.15 nV/√Hz 8.6 nV/√Hz

en @ 10 Hz 4.2 nV/√Hz 10.2 nV/√Hz I

4.0 mA 1.3 mA 11 µA3 µA

Bandwidth 1 kHz 1 kHz Closed-Loop Gain 1,000 1,000

Driving Heavy Loads

The OP295/OP495 is 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 its 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 3a. 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 3b shows the voltages at the inverting and non- inverting outputs of the driver. There is a small crossover glitch that is frequency dependent and would not cause problems unless this was a low distortion application such as audio. If this is used to drive inductive loads, be sure to add diode clamps to protect the bridge from inductive kickback.

2N2222

2N2907

VIN 2.5V

5k⍀

1.67V

10k⍀ 10k⍀

10k⍀

2N2222

OUTPUTS

2N2907

Figure 3a. “H” Bridge

100

Direct Access Arrangement

OP295/OP495 can be used in a single-supply direct access arrangement (DAA) as is shown in Figure 4. 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. Amplifiers A2 and 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 that the drive to the transformer is effectively doubled over a single amplifier arrangement. This application takes advantage of the OP295/ OP495’s ability to drive capacitive loads, and to save power in single-supply applications.

390pF

37.4k⍀

0.1␮F

RXA

0.0047␮F

OP295/

3.3k⍀

OP295/ OP495

20k⍀

475⍀

OP495

22.1k⍀

0.1␮F

TXA

2.5V REF

20k⍀

OP295/ OP495

750pF

20k⍀

0.033␮F

1:1

Figure 4. Direct Access Arrangement

A Single-Supply Instrumentation Amplifier

The OP295/OP495 can be configured as a single-supply instrumentation amplifier as in Figure 5. For our example, V equal to V+/2 and V

is measured with respect to V

REF

is set

REF

. The input common-mode voltage range includes ground and the output swings to both rails.

1/2

V+

OP295/

OP495

100k⍀

REF

1/2

OP295/

OP495

20k⍀ 20k⍀ 100k⍀

VO = 5 +

200k⍀

VIN + V

REF

1ms

Figure 3b. “H” Bridge Outputs

Figure 5. 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 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.

REV. D–8–

Page 9

OP295/OP495

5V 5V

17.8k⍀

1.23V

AD589

4 765

GND CLK SRI

REF

DIGITAL

CONTROL

OP295/ OP495

R3 5k⍀

41.2k⍀

100k⍀

4096

= (4.096V)

TOTA L POWER DISSIPATION = 1.6mW

OUT

DAC8043

A 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 µA current to the bridge. The return current drops across the parallel resistors 6.19 kΩ and the 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.

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.

ZERO ADJ

10-TURNS

26.7k⍀

2.55M⍀ 1%

0.5%

100⍀ RTD

200⍀

100⍀

0.5%

6.19k⍀ 1%

26.7k⍀

0.5%

AD589

OP295/

OP495

1.235

1/2

37.4k⍀

AMP04

50⍀

332⍀

0.22␮F

4.5V = 450ⴗC 0V = 0ⴗC

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 µA supply current from a 9 V battery.

A 5 V Only, 12-Bit DAC That Swings 0 V to 4.095 V

Figure 8 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 the DAC. The V

, which is normally the input now becomes

REF

OUT

) of

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.

A Cold Junction Compensated, Battery-Powered Thermocouple Amplifier

The OP295/OP495’s 150 µA quiescent current per amplifier consumption makes it 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.

ISOTHERMAL

BLOCK

ALUMEL

CHROMEL

K-TYPE THERMOCOUPLE

40.7␮V/ ⴗC

Figure 7. Battery-Powered, Cold-Junction Compensated Thermocouple Amplifier

To calibrate, immerse the thermocouple measuring junction in a 0°C ice bath, adjust the 500 Ω zero-adjust potentiometer to 0 V out. Then immerse the thermocouple in a 250°C temperature

REV. D

Figure 6. Low Power RTD Amplifier

1.235V

24.9k⍀

1N914

COLD JUNCTIONS

AD589

7.15k⍀

1.5M⍀1%24.9k⍀

475⍀

24.3k⍀ 1%

4.99k⍀ 1%

500⍀ 10-TURN

ZERO ADJUST

2.1k⍀ 1%

1.33M⍀

SCALE

ADJUST

20k⍀

OP295/ OP495

5V = 500ⴗC 0V = 0ⴗC

Figure 8. A 5 V 12-Bit DAC with 0 V to 4.095 Output Swing

4 mA to 20 mA Current Loop Transmitter

Figure 9 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 with 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.

SPAN ADJ

0 + 3V

10k⍀

10-TURN

182k⍀

100k⍀

1.21M 1%

HP 5082-2800

NULL ADJ

220pF

100k⍀

REF02

GND

1/2

100⍀

220⍀

2N1711

OP295/

OP495

100⍀

4 TO

20mA

12V

36V

Figure 9. 4 to 20 mA Current Loop Transmitter

–9–

100⍀

Page 10

OP295/OP495

A 3 V Low-Dropout Linear Voltage Regulator

Figure 10 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’s rail-to-rail output swing handily 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.

< 50mA

1.235V

44.2k⍀ 1%

30.9k⍀ 1%

OP295/

OP495

1/2

100␮F

5V TO 3.2V

MJE 350

43k⍀

1000pF

AD589

Figure 10. 3 V Low Dropout Voltage Regulator

Figure 11 shows the regulator’s recovery characteristic when its output underwent a 20 mA to 50 mA step current change.

100

50mA

20mA

OUTPUT

20mV

1ms

STEP CURRENT CONTROL

WAVEFORM

Figure 11. Output Step Load Current Recovery

Low-Dropout, 500 mA Voltage Regulator with Fold-Back Current Limiting

Adding a second amplifier in the regulation loop, as shown in Figure 12, provides an output current monitor as well as foldback current limiting protection.

Amplifier A1 provides error amplification for the normal voltage regulation loop. As long as the output current is less than 1 A, amplifier A2’s output 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 Ω sense resistor forces the amplifier A2’s output to go high, forward-biasing the diode, which in turn closes the current limit loop. At this point 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 “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.

The OP295’s rail-to-rail swing 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.

SENSE

0.1⍀ 1/4W

(NORM) = 0.5A

(MAX) = 1A

205k⍀ 1%

45.3k⍀ 1%

124k⍀

5V V

IRF9531

1N4148

1/2

OP295/

OP495

0.01␮F

1/2

100k⍀

OP295/

210k⍀ 1%

45.3k⍀ 1%

124k⍀

OP495

REF43

2.500V

Figure 12. Low Dropout, 500 mA Voltage Regulator with Fold-Back Current Limiting

Square Wave Oscillator

The circuit in Figure 13 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 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, remains 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 Ω load, the OP295/OP495 can swing close to 5 V p-p across the load.

REV. D–10–

Page 11

OP295/OP495

V+

100k⍀

58.7k⍀

1/2

OP295/ OP495

FREQ OUT

OSC

< 350Hz @ V+ = 5V

Figure 13. Square Wave Oscillator Has Stable Frequency Regardless of Supply Changes

90.9k⍀90.9k⍀

20k⍀ 20k⍀

V+

10k⍀

2.2␮F

10k⍀

1/4 OP295/ OP495

100k⍀

V+

1/4 OP295/ OP495

SPEAKER

Figure 14. Single-Supply Differential Speaker Driver

High Accuracy, Single-Supply, Low Power Comparator

The OP295/OP495 makes an accurate open-loop comparator. With a single 5 V supply, the offset error is less than 300 µV. Figure 15 shows the OP295/OP495’s response time when operating open-loop with 4 mV overdrive. It exhibits a 4 ms response time at the rising edge and a 1.5 ms response time at the falling edge.

100

INPUT

(5mV OVERDRIVE

@ OP-295 INPUT)

OUTPUT

5ms

Figure 15. Open-Loop Comparator Response Time with 5 mV Overdrive

OP295/OP495 SPICE MODEL Macro-Model

* Node Assignments * Noninverting Input * Inverting Input * Positive Supply * Negative Supply * Output * * .SUBCKT OP295 1 2 99 50 20 * * INPUT STAGE *

REV. D

–11–

I1 99 4 2E-6 R1 1 6 5E3 R2 2 5 5E3 CIN 1 2 2E-12 IOS 1 2 0.5E-9 D1 5 3 DZ D2 6 3 DZ EOS 7 6 POLY (1) (31,39) 30E-6 0.024 Q1 8 5 4 QP Q2 9 7 4QP R3 8 50 25.8E3 R4 9 50 25.8E3 * * GAIN STAGE * R7 10 98 270E6 G1 98 10 POLY (1) (9,8) –4.26712E-9 27.8E-6 EREF 98 0 (39, 0) 1 R5 99 39 100E3 R6 39 50 100E3 * * COMMON MODE STAGE * ECM 30 98 POLY(2) (1,39) (2,39) 0 0.5 0.5 R12 30 31 1E6 R13 31 98 100 * * OUTPUT STAGE * I2 18 50 1.59E-6 V2 99 12 DC 2.2763 Q4 10 14 50 QNA 1.0 R11 14 50 33 M3 15 10 13 13 MN L=9E-6 W=102E-6 AD=15E-10 AD=15E-10 M4 13 10 50 50 MN L=9E-6 W=50E-6 AD=75E-11 AS=75E-11 D8 10 22 DX V3 22 50 DC 6 M2 20 10 14 14 MN L=9E-6 W=2000E-6 AD=30E-9 AS=30E-9 Q5 17 17 99 QPA 1.0 Q6 18 17 99 QPA 4.0 R8 18 99 2.2E6 Q7 18 19 99 QPA 1.0 R9 99 19 8 C2 18 99 20E-12 M6 15 12 17 99 MP L=9E-6 W=27E-6 AD=405E-12 AS=405E-12 M1 20 18 19 99 MP L=9E-6 W=2000E-6 AD=30E-9 AS=30E-9 D4 21 18 DX V4 99 21 DC 6 R10 10 11 6E3 C3 11 20 50E-12 .MODEL QNA NPN (IS=1.19E-16 BF=253 NF=0.99 VAF=193 IKF=2.76E-3 + ISE=2.57E-13 NE=5 BR=0.4 NR=0.988 VAR=15 IKR=1.465E-4 + ISC=6.9E-16 NC=0.99 RB=2.0E3 IRB=7.73E-6 RBM=132.8 RE=4 RC=209 + CJE=2.1E-13 VJE=0.573 MJE=0.364 FC=0.5 CJC=1.64E-13 VJC=0.534 MJC=0.5 + CJS=1.37E-12 VJS=0.59 MJS=0.5 TF=0.43E-9 PTF=30) .MODEL QPA PNP (IS=5.21E-17 BF=131 NF=0.99 VAF=62 IKF=8.35E-4 + ISE=1.09E-14 NE=2.61 BR=0.5 NR=0.984 VAR=15 IKR=3.96E-5 + ISC=7.58E-16 NC=0.985 RB=1.52E3 IRB=1.67E-5 RBM=368.5 RE=6.31 RC=354.4 + CJE=1.1E-13 VJE=0.745 MJE=0.33 FC=0.5 CJC=2.37E-13 VJC=0.762 MJC=0.4 + CJS =7.11E-13 VJS=0.45 MJS=0.412 TF=1.0E-9 PTF=30) .MODEL MN NMOS (LEVEL=3 VTO=1.3 RS=0.3 RD=0.3 + TOX=8.5E-8 LD=1.48E-6 NSUB=1.53E16 UO=650 DELTA=10 VMAX=2E5 + XJ=1.75E-6 KAPPA=0.8 ETA=0.066 THETA=0.01 TPG=1 CJ=2.9E4 PB=0.837 + MJ=0.407 CJSW=0.5E-9 MJSW=0.33) .MODEL MP PMOS (LEVEL=3 VTO=–1.1 RS=0.7 RD=0.7 + TOX=9.5E-8 LD=1.4E-6 NSUB=2.4E15 UO=650 DELTA=5.6 VMAX=1E5 + XJ=1.75E-6 KAPPA=1.7 ETA=0.71 THETA=5.9E-3 TPG=–1 CJ=1.55E-4

PB=0.56 + MJ=0.442 CJSW=0.4E-9 MJSW=0.33) .MODEL DX D(IS=1E-15) .MODEL DZ D (IS=1E-15, BV=7) .MODEL QP PNP (BF=125)

.ENDS

Page 12

OP295/OP495

OUTLINE DIMENSIONS

8-Lead Plastic Dual In-Line Package [PDIP]

(N-8)

P-Suffix

Dimensions shown in inches and (millimeters)

0.375 (9.53)

0.365 (9.27)

0.355 (9.02)

0.100 (2.54)

0.180 (4.57)

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)

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

COMPLIANT TO JEDEC STANDARDS MO-095AA

BSC

0.295 (7.49)

0.285 (7.24)

0.275 (6.98)

0.015 (0.38) MIN

SEATING PLANE

0.060 (1.52)

0.050 (1.27)

0.045 (1.14)

0.325 (8.26)

0.310 (7.87)

0.300 (7.62)

0.150 (3.81)

0.135 (3.43)

0.120 (3.05)

0.015 (0.38)

0.010 (0.25)

0.008 (0.20)

8-Lead Standard Small Outline Package [SOIC]

Narrow Body

(R-8)

S-Suffix

Dimensions shown in millimeters and (inches)

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

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

1.27 (0.0500)

SEATING

PLANE

COMPLIANT TO JEDEC STANDARDS MS-012AA

BSC

6.20 (0.2440)

5.80 (0.2284)

1.75 (0.0688)

1.35 (0.0532)

0.51 (0.0201)

0.31 (0.0122)

0.25 (0.0098)

0.17 (0.0067)

0.50 (0.0196)

0.25 (0.0099)

8ⴗ

1.27 (0.0500)

0ⴗ

0.40 (0.0157)

ⴛ 45ⴗ

14-Lead Plastic Dual In-Line Package [PDIP]

(N-14)

P-Suffix

Dimensions shown in inches and (millimeters)

0.685 (17.40)

0.665 (16.89)

0.645 (16.38)

0.100 (2.54) BSC

0.015 (0.38)

0.180 (4.57) MAX

0.150 (3.81)

0.130 (3.30)

0.110 (2.79)

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

0.022 (0.56)

0.018 (0.46)

0.014 (0.36)

COMPLIANT TO JEDEC STANDARDS MO-095-AB

0.060 (1.52)

0.050 (1.27)

0.045 (1.14)

MIN

0.295 (7.49)

0.285 (7.24)

0.275 (6.99)

SEATING PLANE

0.325 (8.26)

0.310 (7.87)

0.300 (7.62)

0.015 (0.38)

0.010 (0.25)

0.008 (0.20)

0.150 (3.81)

0.135 (3.43)

0.120 (3.05)

16-Lead Standard Small Outline Package [SOIC]

Wide Body

(RW-16) S-Suffix

Dimensions shown in millimeters and (inches)

10.50 (0.4134)

10.10 (0.3976)

1.27 (0.0500) BSC

0.30 (0.0118)

0.10 (0.0039)

COPLANARITY

0.10

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

0.51 (0.0201)

0.31 (0.0122)

COMPLIANT TO JEDEC STANDARDS MS-013AA

7.60 (0.2992)

7.40 (0.2913)

2.65 (0.1043)

2.35 (0.0925)

SEATING PLANE

10.65 (0.4193)

10.00 (0.3937)

0.33 (0.0130)

0.20 (0.0079)

8ⴗ 0ⴗ

0.75 (0.0295)

0.25 (0.0098)

1.27 (0.0500)

0.40 (0.0157)

ⴛ 45ⴗ

REV. D–12–

Page 13

OP295/OP495

Revision History

Location Page

2/04—Data Sheet changed from 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—Data Sheet changed from REV. B to REV. C.

Figure changes to PIN CONNECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Deletion of OP295GBC and OP495GBC from ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Deletion of WAFER TEST LIMITS table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Changes to ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Deletion of DICE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

REV. D

–13–

Page 14

–14–

Page 15

–15–

Page 16

C00331–0–2/04(D)

–16–