Datasheet OP295, OP495 (Analog Devices) - 10
| Fabricante | Analog Devices |
| Descripción | Dual/Quad Rail-to-Rail Operational Amplifiers |
| Páginas / Página | 16 / 10 — OP295/OP495. 100. Table 6. Single-Supply Low Noise Preamp Performance. IC … |
| Revisión | G |
| Formato / tamaño de archivo | PDF / 379 Kb |
| Idioma del documento | Inglés |
OP295/OP495. 100. Table 6. Single-Supply Low Noise Preamp Performance. IC = 1.85 mA. IC = 0.5 mA. 1ms. DIRECT ACCESS ARRANGEMENT
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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
100
185 μA of supply current. However, the output swing does not
90
include the positive rail, and the bandwidth reduces to approxi- mately 250 Hz.
Table 6. Single-Supply Low Noise Preamp Performance IC = 1.85 mA IC = 0.5 mA 10
R1 270 Ω 1.0 kΩ
0%
R3, R4 200 Ω 910 Ω
2V 2V 1ms
0 2 0 1- e 33 n @ 100 Hz 3.15 nV/√Hz 8.6 nV/√Hz 00 en @ 10 Hz 4.2 nV/√Hz 10.2 nV/√Hz Figure 22. H Bridge Outputs ISY 4.0 mA 1.3 mA
DIRECT ACCESS ARRANGEMENT
IB 11 μA 3 μA Bandwidth 1 kHz 1 kHz The OP295/OP495 can be used in a single-supply direct access Closed-Loop Gain 1000 1000 arrangement (DAA), as shown in Figure 23. This figure shows a portion of a typical DM capable of operating from a single 5 V
DRIVING HEAVY LOADS
supply, and it may also work on 3 V supplies with minor modi- The OP295/OP495 are well suited to drive loads by using a fications. Amplifier A2 and Amplifier A3 are configured so that power transistor, Darlington, or FET to increase the current to the transmit signal, TxA, is inverted by A2 and is not inverted the load. The ability to swing to either rail can assure that the by A3. This arrangement drives the transformer differentially so device is turned on hard. This results in more power to the load the drive to the transformer is effectively doubled over a single and an increase in efficiency over using standard op amps with amplifier arrangement. This application takes advantage of the their limited output swing. Driving power FETs is also possible ability of the OP295/OP495 to drive capacitive loads and to save with the OP295/OP495 because of their ability to drive capaci- power in single-supply applications. tive loads of several hundred picofarads without oscillating.
390pF
Without the addition of external transistors, the OP295/OP495
37.4kΩ
can drive loads in excess of ±15 mA with ±15 V or +30 V
OP295/ OP495 20kΩ
supplies. This drive capability is somewhat decreased at lower
0.1µF – RxA A1
supply voltages. At ±5 V supplies, the drive current is ±11 mA.
+ 0.0047µF
Driving motors or actuators in two directions in a single-supply
3.3kΩ 20kΩ
application is often accomplished using an H bridge. The principle is demonstrated in Figure 21. From a single 5 V
+ 475Ω OP295/ A2
supply, this driver is capable of driving loads from 0.8 V to
– OP495
4.2 V in both directions. Figure 22 shows the voltages at the
22.1kΩ
inverting and noninverting outputs of the driver. There is a
0.1µF 750pF
small crossover glitch that is frequency-dependent; it does not
20kΩ TxA 1:1
cause problems unless used in low distortion applications, such
20kΩ 0.033µF
as audio. If this is used to drive inductive loads, diode clamps
20kΩ
should be added to protect the bridge from inductive kickback.
OP295/ – 5V OP495 A3
21 0
2.5V REF +
1- 33 00
2N2222 2N2222
Figure 23. Direct Access Arrangement
10kΩ OUTPUTS SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER 0 ≤ VIN ≤ 2.5V 5kΩ –
The OP295/OP495 can be configured as a single-supply
1.67V +
instrumentation amplifier, as shown in Figure 24. For this
2N2907 10kΩ 10kΩ 2N2907
example, VREF is set equal to V+/2, and VO is measured with respect to VREF. The input common-mode voltage range
–
19 includes ground, and the output swings to both rails. 0 1-
+
033 0 Figure 21. H Bridge Rev. G | Page 10 of 16 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION PIN CONFIGURATIONS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS APPLICATIONS RAIL-TO-RAIL APPLICATION INFORMATION LOW DROP-OUT REFERENCE LOW NOISE, SINGLE-SUPPLY PREAMPLIFIER DRIVING HEAVY LOADS DIRECT ACCESS ARRANGEMENT SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER SINGLE-SUPPLY RTD THERMOMETER AMPLIFIER COLD JUNCTION COMPENSATED, BATTERY-POWERED THERMOCOUPLE AMPLIFIER 5 V ONLY, 12-BIT DAC THAT SWINGS 0 V TO 4.095 V 4 mA TO 20 mA CURRENT-LOOP TRANSMITTER 3 V LOW DROPOUT LINEAR VOLTAGE REGULATOR LOW DROPOUT, 500 mA VOLTAGE REGULATOR WITH FOLDBACK CURRENT LIMITING SQUARE WAVE OSCILLATOR SINGLE-SUPPLY DIFFERENTIAL SPEAKER DRIVER HIGH ACCURACY, SINGLE-SUPPLY, LOW POWER COMPARATOR OUTLINE DIMENSIONS ORDERING GUIDE
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
100
185 μA of supply current. However, the output swing does not
90
include the positive rail, and the bandwidth reduces to approxi- mately 250 Hz.
Table 6. Single-Supply Low Noise Preamp Performance IC = 1.85 mA IC = 0.5 mA 10
R1 270 Ω 1.0 kΩ
0%
R3, R4 200 Ω 910 Ω
2V 2V 1ms
0 2 0 1- e 33 n @ 100 Hz 3.15 nV/√Hz 8.6 nV/√Hz 00 en @ 10 Hz 4.2 nV/√Hz 10.2 nV/√Hz Figure 22. H Bridge Outputs ISY 4.0 mA 1.3 mA
DIRECT ACCESS ARRANGEMENT
IB 11 μA 3 μA Bandwidth 1 kHz 1 kHz The OP295/OP495 can be used in a single-supply direct access Closed-Loop Gain 1000 1000 arrangement (DAA), as shown in Figure 23. This figure shows a portion of a typical DM capable of operating from a single 5 V
DRIVING HEAVY LOADS
supply, and it may also work on 3 V supplies with minor modi- The OP295/OP495 are well suited to drive loads by using a fications. Amplifier A2 and Amplifier A3 are configured so that power transistor, Darlington, or FET to increase the current to the transmit signal, TxA, is inverted by A2 and is not inverted the load. The ability to swing to either rail can assure that the by A3. This arrangement drives the transformer differentially so device is turned on hard. This results in more power to the load the drive to the transformer is effectively doubled over a single and an increase in efficiency over using standard op amps with amplifier arrangement. This application takes advantage of the their limited output swing. Driving power FETs is also possible ability of the OP295/OP495 to drive capacitive loads and to save with the OP295/OP495 because of their ability to drive capaci- power in single-supply applications. tive loads of several hundred picofarads without oscillating.
390pF
Without the addition of external transistors, the OP295/OP495
37.4kΩ
can drive loads in excess of ±15 mA with ±15 V or +30 V
OP295/ OP495 20kΩ
supplies. This drive capability is somewhat decreased at lower
0.1µF – RxA A1
supply voltages. At ±5 V supplies, the drive current is ±11 mA.
+ 0.0047µF
Driving motors or actuators in two directions in a single-supply
3.3kΩ 20kΩ
application is often accomplished using an H bridge. The principle is demonstrated in Figure 21. From a single 5 V
+ 475Ω OP295/ A2
supply, this driver is capable of driving loads from 0.8 V to
– OP495
4.2 V in both directions. Figure 22 shows the voltages at the
22.1kΩ
inverting and noninverting outputs of the driver. There is a
0.1µF 750pF
small crossover glitch that is frequency-dependent; it does not
20kΩ TxA 1:1
cause problems unless used in low distortion applications, such
20kΩ 0.033µF
as audio. If this is used to drive inductive loads, diode clamps
20kΩ
should be added to protect the bridge from inductive kickback.
OP295/ – 5V OP495 A3
21 0
2.5V REF +
1- 33 00
2N2222 2N2222
Figure 23. Direct Access Arrangement
10kΩ OUTPUTS SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER 0 ≤ VIN ≤ 2.5V 5kΩ –
The OP295/OP495 can be configured as a single-supply
1.67V +
instrumentation amplifier, as shown in Figure 24. For this
2N2907 10kΩ 10kΩ 2N2907
example, VREF is set equal to V+/2, and VO is measured with respect to VREF. The input common-mode voltage range
–
19 includes ground, and the output swings to both rails. 0 1-
+
033 0 Figure 21. H Bridge Rev. G | Page 10 of 16 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION PIN CONFIGURATIONS TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ELECTRICAL CHARACTERISTICS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS APPLICATIONS RAIL-TO-RAIL APPLICATION INFORMATION LOW DROP-OUT REFERENCE LOW NOISE, SINGLE-SUPPLY PREAMPLIFIER DRIVING HEAVY LOADS DIRECT ACCESS ARRANGEMENT SINGLE-SUPPLY INSTRUMENTATION AMPLIFIER SINGLE-SUPPLY RTD THERMOMETER AMPLIFIER COLD JUNCTION COMPENSATED, BATTERY-POWERED THERMOCOUPLE AMPLIFIER 5 V ONLY, 12-BIT DAC THAT SWINGS 0 V TO 4.095 V 4 mA TO 20 mA CURRENT-LOOP TRANSMITTER 3 V LOW DROPOUT LINEAR VOLTAGE REGULATOR LOW DROPOUT, 500 mA VOLTAGE REGULATOR WITH FOLDBACK CURRENT LIMITING SQUARE WAVE OSCILLATOR SINGLE-SUPPLY DIFFERENTIAL SPEAKER DRIVER HIGH ACCURACY, SINGLE-SUPPLY, LOW POWER COMPARATOR OUTLINE DIMENSIONS ORDERING GUIDE