Dual/Quad Rail-to-Rail Operational Amplifiers OP295/OP495 Battery-operated instrumentation Servo amplifiers Actuator drives Sensor conditioners Power supply control GENERAL DESCRIPTION Rail-to-rail output swing combined with dc accuracy are the key features of the OP495 quad and OP295 dual CBCMOS operational amplifiers. By using a bipolar front end, lower noise and higher accuracy than those of CMOS designs have been achieved. Both input and output ranges include the negative supply, providing the user with zero-in/zero-out capability. For users of 3.3 V systems such as lithium batteries, the OP295/OP495 are specified for 3 V operation. Maximum offset voltage is specified at 300 μV for 5 V operation, and the open-loop gain is a minimum of 1000 V/mV. This yields performance that can be used to implement high accuracy systems, even in single-supply designs. The ability to swing rail-to-rail and supply 15 mA to the load makes the OP295/OP495 ideal drivers for power transistors and H bridges. This allows designs to achieve higher efficiencies and to transfer more power to the load than previously possible without the use of discrete components. For applications such as transformers that require driving inductive loads, increases in efficiency are also possible. Stability while driving capacitive loads is another benefit of this design over CMOS rail-to-rail amplifiers. This is useful for driving coax cable or large FET transistors. The OP295/OP495 are stable with loads in excess of 300 pF. 2 +IN A 3 V– 4 OP295 TOP VIEW (Not to Scale) 8 V+ 7 OUT B 6 –IN B 5 +IN B 00331-001 1 –IN A Figure 1. 8-Lead Narrow-Body SOIC_N (S Suffix) OUT A 1 8 V+ –IN A 2 7 OUT B +IN A 3 6 –IN B V– 4 5 +IN B OP295 00331-002 APPLICATIONS OUT A Figure 2. 8-Lead PDIP (P Suffix) OUT A 1 14 OUT D –IN A 2 13 –IN D +IN A 3 12 +IN D V+ 4 11 V– +IN B 5 10 +IN C –IN B 6 9 –IN C OUT B 7 8 OUT C OP495 00331-003 Rail-to-rail output swing Single-supply operation: 3 V to 36 V Low offset voltage: 300 μV Gain bandwidth product: 75 kHz High open-loop gain: 1000 V/mV Unity-gain stable Low supply current/per amplifier: 150 μA maximum PIN CONFIGURATIONS Figure 3. 14-Lead PDIP (P Suffix) OUT A 1 16 OUT D –IN A 2 15 –IN D +IN A 3 14 +IN D V+ 4 13 V– +IN B 5 12 +IN C –IN B 6 11 –IN C OUT B 7 10 OUT C NC 8 9 NC OP495 TOP VIEW (Not to Scale) NC = NO CONNECT 00331-004 FEATURES Figure 4. 16-Lead SOIC_W (S Suffix) The OP295 and OP495 are specified over the extended industrial (−40°C to +125°C) temperature range. The OP295 is available in 8-lead PDIP and 8-lead SOIC_N surface-mount packages. The OP495 is available in 14-lead PDIP and 16-lead SOIC_W surface-mount packages. Rev. E Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2006 Analog Devices, Inc. All rights reserved. OP295/OP495 TABLE OF CONTENTS Features .............................................................................................. 1 Driving Heavy Loads ................................................................. 10 Applications....................................................................................... 1 Direct Access Arrangement ...................................................... 10 General Description ......................................................................... 1 Single-Supply Instrumentation Amplifier .............................. 10 Pin Configurations ........................................................................... 1 Single-Supply RTD Thermometer Amplifier ......................... 11 Revision History ............................................................................... 2 Cold Junction Compensated, Battery-Powered Thermocouple Amplifier .......................................................... 11 Specifications..................................................................................... 3 Electrical Characteristics............................................................. 3 Absolute Maximum Ratings............................................................ 5 Thermal Resistance ...................................................................... 5 5 V Only, 12-Bit DAC That Swings 0 V to 4.095 V.................... 11 4 to 20 mA Current-Loop Transmitter.................................... 12 3 V Low Dropout Linear Voltage Regulator............................. 12 ESD Caution.................................................................................. 5 Low Dropout, 500 mA Voltage Regulator with Foldback Current Limiting ........................................................................ 12 Typical Performance Characteristics ............................................. 6 Square Wave Oscillator.............................................................. 13 Applications....................................................................................... 9 Single-Supply Differential Speaker Driver.............................. 13 Rail-to-Rail Application Information........................................ 9 High Accuracy, Single-Supply, Low Power Comparator ...... 13 Low Drop-Out Reference ............................................................ 9 Outline Dimensions ....................................................................... 14 Low Noise, Single-Supply Preamplifier ..................................... 9 Ordering Guide .......................................................................... 16 REVISION HISTORY 5/06—Rev. D to Rev. E Updated Format..................................................................Universal Changes to Features.......................................................................... 1 Changes to Pin Connections........................................................... 1 Updated Outline Dimensions ....................................................... 14 Changes to Ordering Guide .......................................................... 15 3/02—Rev. B to Rev. C Figure changes to Pin Connections ................................................1 Deleted OP295GBC and OP495GBC from Ordering Guide ......3 Deleted Wafer Test Limits Table......................................................3 Changes to Absolute Maximum Ratings........................................4 Deleted Dice Characteristics............................................................4 2/04—Rev. C to Rev. D Changes to General Description .................................................... 1 Changes to Specifications ................................................................ 2 Changes to Absolute Maximum Ratings ....................................... 4 Changes to Ordering Guide ............................................................ 4 Updated Outline Dimensions ....................................................... 12 Rev. E | Page 2 of 16 OP295/OP495 SPECIFICATIONS ELECTRICAL CHARACTERISTICS VS = 5.0 V, VCM = 2.5 V, TA = 25°C, unless otherwise noted. Table 1. Parameter INPUT CHARACTERISTICS Offset Voltage Symbol Conditions Min VOS Typ Max Unit 30 300 800 20 30 ±3 ±5 4.0 μA μA nA nA nA nA V dB V/mV V/mV μV/°C −40°C ≤ TA ≤ +125°C Input Bias Current IB 8 −40°C ≤ TA ≤ +125°C Input Offset Current IOS ±1 −40°C ≤ TA ≤ +125°C Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain VCM CMRR AVO Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage Swing High VOH Output Voltage Swing Low VOL Output Current POWER SUPPLY Power Supply Rejection Ratio IOUT Supply Current per Amplifier DYNAMIC PERFORMANCE Skew Rate Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density 0 V ≤ VCM ≤ 4.0 V, −40°C ≤ TA ≤ +125°C RL = 10 kΩ, 0.005 ≤ VOUT ≤ 4.0 V RL = 10 kΩ, −40°C ≤ TA ≤ +125°C 0 90 1000 500 ΔVOS/ΔT PSRR ISY 110 10,000 1 RL = 100 kΩ to GND RL = 10 kΩ to GND IOUT = 1 mA, −40°C ≤ TA ≤ +125°C RL = 100 kΩ to GND RL = 10 kΩ to GND IOUT = 1 mA, −40°C ≤ TA ≤ +125°C 4.98 4.90 ±11 ±1.5 V ≤ VS ≤ ±15 V ±1.5 V ≤ VS ≤ ±15 V, –40°C ≤ TA ≤ +125°C VOUT = 2.5 V, RL = ∞, −40°C ≤ TA ≤ +125°C 90 85 5.0 4.94 4.7 0.7 0.7 90 ±18 5 2 2 110 150 V V V mV mV mV mA dB dB μA SR GBP θO RL = 10 kΩ 0.03 75 86 V/μs kHz Degrees en p-p en in 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 1.5 51 <0.1 μV p-p nV/√Hz pA/√Hz VS = 3.0 V, VCM = 1.5 V, TA = 25°C, unless otherwise noted. Table 2. Parameter INPUT CHARACTERISTICS Offset Voltage Input Bias Current Input Offset Current Input Voltage Range Common-Mode Rejection Ration Large Signal Voltage Gain Offset Voltage Drift Symbol VOS IB IOS VCM CMRR AVO ∆VOS/∆T Conditions 0 V ≤ VCM ≤ 2.0 V, −40°C ≤ TA ≤ +125°C RL = 10 kΩ Rev. E | Page 3 of 16 Min 0 90 Typ Max Unit 100 8 ±1 500 20 ±3 2.0 μV nA nA V dB V/mV μV/°C 110 750 1 OP295/OP495 Parameter OUTPUT CHARACTERISTICS Output Voltage Swing High Output Voltage Swing Low POWER SUPPLY Power Supply Rejection Ratio Symbol Conditions Min VOH VOL RL = 10 kΩ to GND RL = 10 kΩ to GND 2.9 PSRR 90 85 Supply Current per Amplifier DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density ISY ±1.5 V ≤ VS ≤ ±15 V ±1.5 V ≤ VS ≤ ±15 V, −40°C ≤ TA ≤ +125°C VOUT = 1.5 V, RL = ∞, −40°C ≤ TA ≤ +125°C Typ Max Unit 0.7 2 V mV 150 dB dB μA 110 SR GBP θO RL = 10 kΩ 0.03 75 85 V/μs kHz Degrees en p-p en in 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 1.6 53 <0.1 μV p-p nV/√Hz pA/√Hz VS = ±15.0 V, TA = 25°C, unless otherwise noted. Table 3. Parameter INPUT CHARACTERISTICS Offset Voltage Symbol IB Input Offset Current IOS VCM CMRR AVO ΔVOS/ΔT VOH Output Voltage Swing Low VOL Output Current POWER SUPPLY Power Supply Rejection Ratio IOUT Supply Current per Amplifier Supply Voltage Range DYNAMIC PERFORMANCE Slew Rate Gain Bandwidth Product Phase Margin NOISE PERFORMANCE Voltage Noise Voltage Noise Density Current Noise Density Min Typ Max Unit 300 500 800 20 30 ±3 ±5 +13.5 110 4000 1 μV μV nA nA nA nA V dB V/mV μV/°C ±15 ±25 V V V V mA 90 85 110 VOS Input Bias Current Input Voltage Range Common-Mode Rejection Ratio Large Signal Voltage Gain Offset Voltage Drift OUTPUT CHARACTERISTICS Output Voltage Swing High Conditions PSRR ISY VS −40°C ≤ TA ≤ +125°C VCM = 0 V VCM = 0 V, −40°C ≤ TA ≤ +125°C VCM = 0 V VCM = 0 V, −40°C ≤ TA ≤ +125°C −15.0 V ≤ VCM ≤ +13.5 V, −40°C ≤ TA ≤ +125°C RL = 10 kΩ RL = 100 kΩ to GND RL = 10 kΩ to GND RL = 100 kΩ to GND RL = 10 kΩ to GND VS = ±1.5 V to ±15 V VS = ±1.5 V to ±15 V, −40°C ≤ TA ≤ +125°C VO = 0 V, RL = ∞, VS = ±18 V, −40°C ≤ TA ≤ +125°C 7 ±1 −15 90 1000 14.95 14.80 −14.95 −14.85 175 36 (± 18) 3 (± 1.5) dB dB μA V SR GBP θO RL = 10 kΩ 0.03 85 83 V/μs kHz Degrees en p-p en in 0.1 Hz to 10 Hz f = 1 kHz f = 1 kHz 1.25 45 <0.1 μV p-p nV/√Hz pA/√Hz Rev. E | Page 4 of 16 OP295/OP495 ABSOLUTE MAXIMUM RATINGS Table 4. Parameter1 Supply Voltage Input Voltage Differential Input Voltage2 Output Short-Circuit Duration Storage Temperature Range P, S Package Operating Temperature Range OP295G, OP495G Junction Temperature Range P, S Package Lead Temperature (Soldering, 60 sec) 1 2 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Rating ±18 V ±18 V 36 V Indefinite −65°C to +150°C THERMAL RESISTANCE –40°C to +125°C θJA is specified for worst case mounting conditions; that is, θJA is specified for device in socket for PDIP; θJA is specified for device soldered to printed circuit board for SOIC package. –65°C to +150°C 300°C Table 5. Thermal Resistance Absolute maximum ratings apply to packaged parts, unless otherwise noted. For supply voltages less than ±18 V, the absolute maximum input voltage is equal to the supply voltage. Package Type 8-Lead PDIP (P Suffix) 8-Lead SOIC_N (S Suffix) 14-Lead PDIP (P Suffix) 16-Lead SOIC_W (S Suffix) θJA 103 158 83 98 ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. E | Page 5 of 16 θJC 43 43 39 30 Unit °C/W °C/W °C/W °C/W OP295/OP495 TYPICAL PERFORMANCE CHARACTERISTICS 140 200 120 125 VS = 5V 80 VS = 3V 100 75 60 50 40 25 50 75 100 TEMPERATURE (°C) 0 –250 –200 –150 –100 250 RL = 100kΩ BASED ON 600 OP AMPS 100 150 200 250 3.2 VS = 5V –40°C ≤ TA ≤ +85°C 225 14.8 200 RL = 10kΩ 14.6 175 14.4 RL = 2kΩ 150 UNITS 14.2 125 100 –14.4 –14.6 –14.8 –15.0 RL = 2kΩ 75 RL = 10kΩ 50 25 RL = 100kΩ –50 –25 0 25 50 TEMPERATURE (°C) 75 100 0 0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 TCVOS (µV/°C) Figure 9. OP295 TCVOS Distribution Figure 6. Output Voltage Swing vs. Temperature 5.1 3.1 VS = 3V VS = 5V OUTPUT VOLTAGE SWING (V) 3.0 RL = 100kΩ 2.9 RL = 10kΩ 2.8 2.7 RL = 2kΩ 2.6 RL = 100kΩ 4.9 RL = 10kΩ 4.8 4.7 RL = 2kΩ 4.6 –25 0 25 50 75 TEMPERATURE (°C) 100 00331-007 2.5 –50 5.0 4.5 –50 –25 0 25 50 75 TEMPERATURE (°C) Figure 10. Output Voltage Swing vs. Temperature Figure 7. Output Voltage Swing vs. Temperature Rev. E | Page 6 of 16 100 00331-010 –15.2 50 Figure 8. OP295 Input Offset (VOS) Distribution 00331-006 + OUTPUT SWING (V) – OUTPUT SWING (V) VS = ±15V 15.0 0 INPUT OFFSET VOLTAGE (µV) Figure 5. Supply Current Per Amplifier vs. Temperature 15.2 –50 00331-008 0 00331-005 –25 00331-009 25 20 –50 OUTPUT VOLTAGE SWING (V) VS = 5V TA = 25°C 150 VS = 36V 100 UNITS SUPPLY CURRENT (µA) BASED ON 600 OP AMPS 175 OP295/OP495 500 BASED ON 1200 OP AMPS 40 VS = 5V TA = 25°C 450 SOURCE 35 OUTPUT CURRENT (mA) 400 350 250 200 150 100 VS = ±15V 25 SOURCE 20 SINK 15 VS = +5V 10 5 50 –50 0 50 100 150 200 INPUT OFFSET VOLTAGE (µV) 250 300 0 –50 00331-011 0 –100 –25 BASED ON 1200 OP AMPS 50 75 100 Figure 14. Output Current vs. Temperature 100 VS = 5V –40°C ≤ TA ≤ +85°C 450 25 TEMPERATURE (°C) Figure 11. OP495 Input Offset (VOS) Distribution 500 0 00331-013 UNITS 300 SINK 30 VS = ±15V VO = ±10V OPEN-LOOP GAIN (V/µV) 400 350 UNITS 300 250 200 150 RL = 100kΩ 10 RL = 10kΩ 100 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 TCVOS (µV/°C) 0 25 50 75 100 100 TEMPERATURE (°C) Figure 15. Open-Loop Gain vs. Temperature Figure 12. OP495 TCVOS Distribution 20 12 VS = 5V VO = 4V VS = 5V 10 OPEN-LOOP GAIN (V/µV) 16 12 8 4 0 –50 8 RL = 100kΩ 6 RL = 10kΩ 4 RL = 2kΩ 2 –25 0 25 50 TEMPERATURE (°C) 75 100 0 –50 00331-033 INPUT BIAS CURRENT (nA) –25 00331-014 0 1 –50 00331-012 0 00331-015 RL = 2kΩ 50 –25 0 25 50 75 TEMPERATURE (°C) Figure 16. Open-Loop Gain vs. Temperature Figure 13. Input Bias Current vs. Temperature Rev. E | Page 7 of 16 OP295/OP495 1V 100mV SOURCE 10mV SINK 1mV 100µV 1µA 10µA 100µA 1mA LOAD CURRENT 10mA 00331-016 OUTPUT VOLTAGE Δ TO RAIL VS = 5V TA = 25°C Figure 17. Output Voltage to Supply Rail vs. Load Current Rev. E | Page 8 of 16 OP295/OP495 APPLICATIONS RAIL-TO-RAIL APPLICATION INFORMATION The OP295/OP495 have a wide common-mode input range extending from ground to within about 800 mV of the positive supply. There is a tendency to use the OP295/OP495 in buffer applications where the input voltage could exceed the commonmode input range. This can initially appear to work because of the high input range and rail-to-rail output range. But above the common-mode input range, the amplifier is, of course, highly nonlinear. For this reason, there must be some minimal amount of gain when rail-to-rail output swing is desired. Based on the input common-mode range, this gain should be at least 1.2. R5 and R6 set the gain of 1000, making this circuit ideal for maximizing dynamic range when amplifying low level signals in single-supply applications. The OP295/OP495 provide rail-torail output swings, allowing this circuit to operate with 0 V to 5 V outputs. Only half of the OP295/OP495 is used, leaving the other uncommitted op amp for use elsewhere. 0.1µF LED 3 The OP295/OP495 can be used to gain up a 2.5 V or other low voltage reference to 4.5 V for use with high resolution ADCs that operate from 5 V only supplies. The circuit in Figure 18 supplies up to 10 mA. Its no-load drop-out voltage is only 20 mV. This circuit supplies over 3.5 mA with a 5 V supply. 5 Q1 R6 10Ω 6 MAT03 Q2 7 2 – 8 R7 510Ω R2 27kΩ – C2 10µF VOUT 1 3 C1 1500pF R8 100Ω + 4 OP295/OP495 R4 00331-018 R3 R5 10kΩ 0.001µF 5V Figure 19. Low Noise Single-Supply Preamplifier 5V 2 6 – + 10Ω 1µF TO 10µF VOUT = 4.5V + 1/2 OP295/OP495 00331-017 20kΩ 4 2 1 16kΩ REF43 10µF + Q2 2N3906 VIN LOW DROP-OUT REFERENCE R1 Figure 18. 4.5 V, Low Drop-Out Reference LOW NOISE, SINGLE-SUPPLY PREAMPLIFIER Most single-supply op amps are designed to draw low supply current at the expense of having higher voltage noise. This tradeoff may be necessary because the system must be powered by a battery. However, this condition is worsened because all circuit resistances tend to be higher; as a result, in addition to the op amp’s voltage noise, Johnson noise (resistor thermal noise) is also a significant contributor to the total noise of the system. The choice of monolithic op amps that combine the characteristics of low noise and single-supply operation is rather limited. Most single-supply op amps have noise on the order of 30 nV/√Hz to 60 nV/√Hz, and single-supply amplifiers with noise below 5 nV/√Hz do not exist. To achieve both low noise and low supply voltage operation, discrete designs may provide the best solution. The circuit in Figure 19 uses the OP295/OP495 rail-to-rail amplifier and a matched PNP transistor pair—the MAT03—to achieve zeroin/zero-out single-supply operation with an input voltage noise of 3.1 nV/√Hz at 100 Hz. The input noise is controlled by the MAT03 transistor pair and the collector current level. Increasing the collector current reduces the voltage noise. This particular circuit was tested with 1.85 mA and 0.5 mA of current. Under these two cases, the input voltage noise was 3.1 nV/√Hz and 10 nV/√Hz, respectively. The high collector currents do lead to a tradeoff in supply current, bias current, and current noise. All of these parameters increase with increasing collector current. For example, typically the MAT03 has an hFE = 165. This leads to bias currents of 11 μA and 3 μA, respectively. Based on the high bias currents, this circuit is best suited for applications with low source impedance such as magnetic pickups or low impedance strain gauges. Furthermore, a high source impedance degrades the noise performance. For example, a 1 kΩ resistor generates 4 nV/√Hz of broadband noise, which is already greater than the noise of the preamp. The collector current is set by R1 in combination with the LED and Q2. The LED is a 1.6 V Zener diode that has a temperature coefficient close to that of the Q2 base-emitter junction, which provides a constant 1.0 V drop across R1. With R1 equal to 270 Ω, the tail current is 3.7 mA and the collector current is half that, or 1.85 mA. The value of R1 can be altered to adjust the collector current. When R1 is changed, R3 and R4 should also be adjusted. To maintain a common-mode input range that includes ground, the collectors of the Q1 and Q2 should not go above 0.5 V; otherwise, they could saturate. Thus, R3 and R4 must be small enough to prevent this condition. Their values and the overall performance for two different values of R1 are summarized in Table 6. Rev. E | Page 9 of 16 OP295/OP495 Finally, the potentiometer, R8, is needed to adjust the offset voltage to null it to zero. Similar performance can be obtained using an OP90 as the output amplifier with a savings of about 185 μA of supply current. However, the output swing does not include the positive rail, and the bandwidth reduces to approximately 250 Hz. 100 90 Table 6. Single-Supply Low Noise Preamp Performance IC = 1.85 mA 270 Ω IC = 0.5 mA 1.0 kΩ R3, R4 en @ 100 Hz en @ 10 Hz ISY IB Bandwidth Closed-Loop Gain 200 Ω 3.15 nV/√Hz 4.2 nV/√Hz 4.0 mA 11 μA 1 kHz 1000 910 Ω 8.6 nV/√Hz 10.2 nV/√Hz 1.3 mA 3 μA 1 kHz 1000 10 0% 2V 00331-020 R1 1ms 2V Figure 21. H Bridge Outputs DIRECT ACCESS ARRANGEMENT DRIVING HEAVY LOADS The OP295/OP495 are well suited to drive loads by using a power transistor, Darlington, or FET to increase the current to the load. The ability to swing to either rail can assure that the device is turned on hard. This results in more power to the load and an increase in efficiency over using standard op amps with their limited output swing. Driving power FETs is also possible with the OP295/OP495 because of their ability to drive capacitive loads of several hundred picofarads without oscillating. The OP295/OP495 can be used in a single-supply direct access arrangement (DAA), as shown in Figure 22. This figure shows a portion of a typical DM capable of operating from a single 5 V supply, and it may also work on 3 V supplies with minor modifications. Amplifier A2 and Amplifier A3 are configured so that the transmit signal, TxA, is inverted by A2 and is not inverted by A3. This arrangement drives the transformer differentially so the drive to the transformer is effectively doubled over a single amplifier arrangement. This application takes advantage of the ability of the OP295/OP495 to drive capacitive loads and to save power in single-supply applications. 390pF Without the addition of external transistors, the OP295/OP495 can drive loads in excess of ±15 mA with ±15 V or +30 V supplies. This drive capability is somewhat decreased at lower supply voltages. At ±5 V supplies, the drive current is ±11 mA. 37.4kΩ 0.1µF RxA OP295/ OP495 20kΩ 0.0047µF Driving motors or actuators in two directions in a single-supply application is often accomplished using an H bridge. The principle is demonstrated in Figure 20. From a single 5 V supply, this driver is capable of driving loads from 0.8 V to 4.2 V in both directions. Figure 21 shows the voltages at the inverting and noninverting outputs of the driver. There is a small crossover glitch that is frequency-dependent; it does not cause problems unless used in low distortion applications, such as audio. If this is used to drive inductive loads, diode clamps should be added to protect the bridge from inductive kickback. 3.3kΩ + A2 20kΩ 475Ω – OP295/ OP495 22.1kΩ 0.1µF TxA 20kΩ 750pF 20kΩ 0.033µF 1:1 2.5V REF 2N2222 OP295/ OP495 – A3 + 00331-021 20kΩ 5V 2N2222 – A1 + Figure 22. Direct Access Arrangement 10kΩ 5kΩ 1.67V 10kΩ SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER OUTPUTS – + 10kΩ 2N2907 – + 2N2907 00331-019 0 ≤ VIN ≤ 2.5V The OP295/OP495 can be configured as a single-supply instrumentation amplifier, as shown in Figure 23. For this example, VREF is set equal to V+/2, and VO is measured with respect to VREF. The input common-mode voltage range includes ground, and the output swings to both rails. Figure 20. H Bridge Rev. E | Page 10 of 16 OP295/OP495 1/2 OP295/ OP495 + – 3 + 2 – + 8 6 – 4 COLD JUNCTION COMPENSATED, BATTERYPOWERED THERMOCOUPLE AMPLIFIER VO 7 1/2 OP295/ OP495 VIN 5 The 150 μA quiescent current per amplifier consumption of the OP295/OP495 makes them useful for battery-powered temperature measuring instruments. The K-type thermocouple terminates into an isothermal block where the terminated junctions’ ambient temperatures can be continuously monitored and corrected by summing an equal but opposite thermal EMF to the amplifier, thereby canceling the error introduced by the cold junctions. 1 R1 100kΩ R2 20kΩ VREF R3 20kΩ R4 100kΩ RG ) 00331-022 ( VO = 5 + 200kΩ VIN + VREF RG AD589 1.235V 24.9kΩ 9V ISOTHERMAL BLOCK Figure 23. Single-Supply Instrumentation Amplifier 1N914 Resistor RG sets the gain of the instrumentation amplifier. Minimum gain is 6 (with no RG). All resistors should be matched in absolute value as well as temperature coefficient to maximize common-mode rejection performance and minimize drift. This instrumentation amplifier can operate from a supply voltage as low as 3 V. SINGLE-SUPPLY RTD THERMOMETER AMPLIFIER ALUMEL – AL 1.5MΩ 1% 7.15kΩ 1% 24.3kΩ 1% 24.9kΩ 1% 4.99kΩ 1% COLD JUNCTIONS 500Ω 10-TURN + CR CHROMEL K-TYPE THERMOCOUPLE 40.7µV/°C ZERO ADJUST 475Ω 1% 2.1kΩ 1% + – SCALE ADJUST 20kΩ 1.33MΩ 2 – 8 3 + 4 1 OP295/ OP495 VO 5V = 500°C 0V = 0°C 00331-024 V+ Figure 25. Battery-Powered, Cold-Junction Compensated Thermocouple Amplifier This RTD amplifier takes advantage of the rail-to-rail swing of the OP295/OP495 to achieve a high bridge voltage in spite of a low 5 V supply. The OP295/OP495 amplifier servos a constant 200 μA current to the bridge. The return current drops across the parallel resistors 6.19 kΩ and 2.55 MΩ, developing a voltage that is servoed to 1.235 V, which is established by the AD589 band gap reference. The 3-wire RTD provides an equal line resistance drop in both 100 Ω legs of the bridge, thus improving the accuracy. To calibrate, immerse the thermocouple measuring junction in a 0°C ice bath and adjust the 500 Ω zero-adjust potentiometer to 0 V out. Then immerse the thermocouple in a 250°C temperature bath or oven and adjust the scale-adjust potentiometer for an output voltage of 2.50 V, which is equivalent to 250°C. Within this temperature range, the K-type thermocouple is quite accurate and produces a fairly linear transfer characteristic. Accuracy of ±3°C is achievable without linearization. The AMP04 amplifies the differential bridge signal and converts it to a single-ended output. The gain is set by the series resistance of the 332 Ω resistor plus the 50 Ω potentiometer. The gain scales the output to produce a 4.5 V full scale. The 0.22 μF capacitor to the output provides a 7 Hz low-pass filter to keep noise at a minimum. Even if the battery voltage is allowed to decay to as low as 7 V, the rail-to-rail swing allows temperature measurements to 700°C. However, linearization may be necessary for temperatures above 250°C, where the thermocouple becomes rather nonlinear. The circuit draws just under 500 μA supply current from a 9 V battery. 2.55MΩ 1% 50Ω 5V 26.7kΩ 0.5% 100Ω RTD 5 V ONLY, 12-BIT DAC THAT SWINGS 0 V TO 4.095 V ZERO ADJ 26.7kΩ 0.5% 7 3 2 1 100Ω 0.5% Figure 26 shows a complete voltage output DAC with wide output voltage swing operating off a single 5 V supply. The serial input, 12-bit DAC is configured as a voltage output device with the 1.235 V reference feeding the current output pin (IOUT) of the DAC. The VREF, which is normally the input, now becomes the output. 332Ω – + 2 3 6.19kΩ AD589 1% 1/2 OP295/ OP495 1.235 37.4kΩ 1 + 8 0.22µF AMP04 6 VO 5 – 4 4.5V = 450°C 0V = 0°C 5V 00331-023 200Ω 10-TURNS The output voltage from the DAC is the binary weighted voltage of the reference, which is gained up by the output amplifier such that the DAC has a 1 mV per bit transfer function. Figure 24. Low Power RTD Amplifier Rev. E | Page 11 of 16 OP295/OP495 5V DAC8043 IOUT VREF 1 + 3 VO = 8 D 4096 VIN 5V TO 3.2V (4.096V) VO + 44.2kΩ 1% 8 1 4 7 6 OP295/ OP495 4 5 4 TOTAL POWER DISSIPATION = 1.6mW 43kΩ Figure 27 shows a self-powered 4 to 20 mA current-loop transmitter. The entire circuit floats up from the single-supply (12 V to 36 V) return. The supply current carries the signal within the 4 to 20 mA range. Thus, the 4 mA establishes the baseline current budget within which the circuit must operate. This circuit consumes only 1.4 mA maximum quiescent current, making 2.6 mA of current available to power additional signal conditioning circuitry or to power a bridge circuit. VIN 0V + 3V 10kΩ 10-TURN 100kΩ 10-TURN 1.21MΩ 1% 3 182kΩ 1% + – – 8 1/2 OP295/ OP495 10 0% 20mV 100Ω 12V TO 36V 2N1711 4mA TO 20mA 220pF 100kΩ HP 5082-2800 1% 90 20mA OUTPUT 220Ω 4 50mA STEP CURRENT CONTROL WAVEFORM 2 1 2 2V 4 5V AD589 100 GND 1ms Figure 29. Output Step Load Current Recovery LOW DROPOUT, 500 mA VOLTAGE REGULATOR WITH FOLDBACK CURRENT LIMITING RL 100Ω 100Ω 1% 00331-026 SPAN ADJ REF02 1/2 OP295/ OP495 Figure 29 shows the regulator’s recovery characteristic when its output underwent a 20 mA to 50 mA step current change. 4 TO 20 mA CURRENT-LOOP TRANSMITTER 6 2 Figure 28. 3 V Low Dropout Voltage Regulator Figure 26. A 5 V 12-Bit DAC with 0 V to 4.095 Output Swing + – 1.235V R3 5kΩ NULL ADJ 30.9kΩ 1% 1000pF R4 100kΩ R2 41.2kΩ DIGITAL CONTROL 3 1 00331-025 AD589 – 2 GND CLK SRI LD + + 100µF 00331-027 3 RFB 2 VDD MJE 350 5V 00331-028 1.23V IL < 50mA 8 R1 17.8kΩ Figure 27. 4 to 20 mA Current Loop Transmitter Adding a second amplifier in the regulation loop, as shown in Figure 30, provides an output current monitor as well as foldback current limiting protection. 3 V LOW DROPOUT LINEAR VOLTAGE REGULATOR Figure 28 shows a simple 3 V voltage regulator design. The regulator can deliver 50 mA load current while allowing a 0.2 V dropout voltage. The OP295/OP495 rail-to-rail output swing drives the MJE350 pass transistor without requiring special drive circuitry. At no load, its output can swing less than the pass transistor’s base-emitter voltage, turning the device nearly off. At full load, and at low emitter-collector voltages, the transistor beta tends to decrease. The additional base current is easily handled by the OP295/OP495 output. I (NORM) = 0.5A RSENSE O IO (MAX) = 1A 0.1Ω 1/4W 5V VO IRF9531 S D + 6V – G 45.3kΩ 1% 45.3kΩ 1% + 5 A2 7 1/2 OP295/ OP495 – 6 0.01µF 1 1/2 OP295/ OP495 The amplifier servos the output to a constant voltage, which feeds a portion of the signal to the error amplifier. 2 Higher output current, to 100 mA, is achievable at a higher dropout voltage of 3.8 V. 205kΩ 1% 8 1N4148 100kΩ 5% 210kΩ 1% REF43 4 + 3 124kΩ A1 1% 4 – 2 6 124kΩ 1% 2.5V Figure 30. Low Dropout, 500 mA Voltage Regulator with Foldback Current Limiting Rev. E | Page 12 of 16 00331-029 5V OP295/OP495 If the output current greater than 1 A persists, the current limit loop forces a reduction of current to the load, which causes a corresponding drop in output voltage. As the output voltage drops, the current-limit threshold also drops fractionally, resulting in a decreasing output current as the output voltage decreases, to the limit of less than 0.2 A at 1 V output. This foldback effect reduces the power dissipation considerably during a short circuit condition, thus making the power supply far more forgiving in terms of the thermal design requirements. Small heat sinking on the power MOSFET can be tolerated. The rail-to-rail swing of the OP295 exacts higher gate drive to the power MOSFET, providing a fuller enhancement to the transistor. The regulator exhibits 0.2 V dropout at 500 mA of load current. At 1 A output, the dropout voltage is typically 5.6 V. SQUARE WAVE OSCILLATOR The circuit in Figure 31 is a square wave oscillator (note the positive feedback). The rail-to-rail swing of the OP295/OP495 helps maintain a constant oscillation frequency even if the supply voltage varies considerably. Consider a battery-powered system where the voltages are not regulated and drop over time. The rail-to-rail swing ensures that the noninverting input sees the full V+/2, rather than only a fraction of it. V+ 100kΩ 58.7kΩ 3 + 8 2 – 4 FREQ OUT 1 + FOSC = 1 < 350Hz @ V+ = 5V RC 00331-030 100kΩ 1/2 OP295/ OP495 R C Figure 31. Square Wave Oscillator Has Stable Frequency Regardless of Supply Changes 90.9kΩ 10kΩ VIN + 2.2µF + – V+ + 10kΩ 100kΩ 1/4 OP295/ OP495 SPEAKER – – + + V+ 20kΩ 20kΩ 1/4 OP295/ OP495 1/4 OP295/ OP495 00331-031 Amplifier A1 provides error amplification for the normal voltage regulation loop. As long as the output current is less than 1 A, the output of Amplifier A2 swings to ground, reversebiasing the diode and effectively taking itself out of the circuit. However, as the output current exceeds 1 A, the voltage that develops across the 0.1 Ω sense resistor forces the output of Amplifier A2 to go high, forward-biasing the diode, which in turn closes the current-limit loop. At this point, the A2’s lower output resistance dominates the drive to the power MOSFET transistor, thereby effectively removing the A1 voltage regulation loop from the circuit. Figure 32. Single-Supply Differential Speaker Driver HIGH ACCURACY, SINGLE-SUPPLY, LOW POWER COMPARATOR The OP295/OP495 make accurate open-loop comparators. With a single 5 V supply, the offset error is less than 300 μV. Figure 33 shows the response time of the OP295/OP495 when operating open-loop with 4 mV overdrive. They exhibit a 4 ms response time at the rising edge and a 1.5 ms response time at the falling edge. 1V 100 90 INPUT (5mV OVERDRIVE @ OP295 INPUT) OUTPUT 10 SINGLE-SUPPLY DIFFERENTIAL SPEAKER DRIVER Connected as a differential speaker driver, the OP295/OP495 can deliver a minimum of 10 mA to the load. With a 600 Ω load, the OP295/OP495 can swing close to 5 V p-p across the load. 0% 2V 5ms Figure 33. Open-Loop Comparator Response Time with 5 mV Overdrive Rev. E | Page 13 of 16 00331-032 The constant frequency comes from the fact that the 58.7 kΩ feedback sets up Schmitt trigger threshold levels that are directly proportional to the supply voltage, as are the RC charge voltage levels. As a result, the RC charge time, and therefore, the frequency, remain constant independent of supply voltage. The slew rate of the amplifier limits oscillation frequency to a maximum of about 800 Hz at a 5 V supply. OP295/OP495 OUTLINE DIMENSIONS 0.400 (10.16) 0.365 (9.27) 0.355 (9.02) 8 5 1 4 0.280 (7.11) 0.250 (6.35) 0.240 (6.10) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) PIN 1 0.100 (2.54) BSC 0.060 (1.52) MAX 0.210 (5.33) MAX 0.150 (3.81) 0.130 (3.30) 0.115 (2.92) 0.195 (4.95) 0.130 (3.30) 0.115 (2.92) 0.015 (0.38) MIN 0.015 (0.38) GAUGE PLANE SEATING PLANE 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) 0.430 (10.92) MAX 0.005 (0.13) MIN 0.014 (0.36) 0.010 (0.25) 0.008 (0.20) 0.070 (1.78) 0.060 (1.52) 0.045 (1.14) COMPLIANT TO JEDEC STANDARDS MS-001-BA CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS. Figure 34. 8-Lead Plastic Dual In-Line Package [PDIP] (N-8) P Suffix Dimensions shown in inches and (millimeters) 5.00 (0.1968) 4.80 (0.1890) 8 4.00 (0.1574) 3.80 (0.1497) 1 5 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 6.20 (0.2440) 4 5.80 (0.2284) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) COPLANARITY SEATING 0.31 (0.0122) 0.10 PLANE 0.50 (0.0196) × 45° 0.25 (0.0099) 8° 0.25 (0.0098) 0° 1.27 (0.0500) 0.40 (0.0157) 0.17 (0.0067) COMPLIANT TO JEDEC STANDARDS MS-012-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure 35. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) S Suffix Dimensions shown in millimeters and (inches) Rev. E | Page 14 of 16 OP295/OP495 0.775 (19.69) 0.750 (19.05) 0.735 (18.67) 14 8 1 7 0.280 (7.11) 0.250 (6.35) 0.240 (6.10) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) PIN 1 0.100 (2.54) BSC 0.060 (1.52) MAX 0.210 (5.33) MAX 0.195 (4.95) 0.130 (3.30) 0.115 (2.92) 0.015 (0.38) MIN 0.150 (3.81) 0.130 (3.30) 0.110 (2.79) 0.015 (0.38) GAUGE PLANE SEATING PLANE 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) 0.430 (10.92) MAX 0.005 (0.13) MIN 0.014 (0.36) 0.010 (0.25) 0.008 (0.20) 0.070 (1.78) 0.050 (1.27) 0.045 (1.14) COMPLIANT TO JEDEC STANDARDS MS-001-AA CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS. Figure 36. 14-Lead Plastic Dual In-Line Package [PDIP] (N-14) P Suffix Dimensions shown in inches and (millimeters) 10.50 (0.4134) 10.10 (0.3976) 9 16 7.60 (0.2992) 7.40 (0.2913) 8 1 1.27 (0.0500) BSC 2.65 (0.1043) 2.35 (0.0925) 0.30 (0.0118) 0.10 (0.0039) COPLANARITY 0.10 10.65 (0.4193) 10.00 (0.3937) 0.51 (0.0201) 0.31 (0.0122) SEATING PLANE 8° 0.33 (0.0130) 0° 0.20 (0.0079) 0.75 (0.0295) × 45° 0.25 (0.0098) 1.27 (0.0500) 0.40 (0.0157) COMPLIANT TO JEDEC STANDARDS MS-013-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. Figure 37. 16-Lead Standard Small Outline Package [SOIC_W] Wide Body (RW-16) S Suffix Dimensions shown in millimeters and (inches) Rev. E | Page 15 of 16 OP295/OP495 ORDERING GUIDE Model OP295GP OP295GPZ 1 OP295GS OP295GS-REEL OP295GS-REEL7 OP295GSZ1 OP295GSZ-REEL1 OP295GSZ-REEL71 OP495GP OP495GPZ1 OP495GS OP495GS-REEL OP495GSZ1 OP495GSZ-REEL1 1 Temperature Range −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C −40°C to +125°C Package Description 8-Lead Plastic DIP 8-Lead Plastic DIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 14-Lead Plastic DIP 14-Lead Plastic DIP 16-Lead SOIC_W 16-Lead SOIC_W 16-Lead SOIC_W 16-Lead SOIC_W Z = Pb-free part. ©2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C00331-0-5/06(E) Rev. E | Page 16 of 16 Package Option P-Suffix (N-8) P-Suffix (N-8) S-Suffix (R-8) S-Suffix (R-8) S-Suffix (R-8) S-Suffix (R-8) S-Suffix (R-8) S-Suffix (R-8) P-Suffix (N-14) P-Suffix (N-14) S-Suffix (RW-16) S-Suffix (RW-16) S-Suffix (RW-16) S-Suffix (RW-16)