Datasheet OP113, OP213, OP413 (Analog Devices) - 14

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OP113/OP213/OP413 APPLICATION CIRCUITS 5V A HIGH PRECISION INDUSTRIAL LOAD-CELL SCALE AMPLIFIER 2 IN 8 2.5V
The OPx13 family makes an excellent amplifier for
+ 3 6 OUT REF43 1/2 2N2222A 1
conditioning a load-cell bridge. Its low noise greatly improves
OP295 GND – 2 4 4
the signal resolution, allowing the load cell to operate with a smaller output range, thus reducing its nonlinearity. Figure 41
4V 5V 350Ω R8 R7
shows one half of the OPx13 family used to generate a very
35mV 12kΩ 20kΩ FS 8 OUTPUT
stable 10 V bridge excitation voltage while the second amplifier
5 + 0V 3.5V 1/2 7
provides a differential gain. R4 should be trimmed for
OP295 6 – 4
maximum common-mode rejection.
3 + R3 +15V 1/2 20kΩ –15V OP213 1 R4 2 16 2 – 100kΩ R2 R5 +10V 8 14 + 3 1 20kΩ 1kΩ 2N2219A 1 A2 15 3 – 2 AD588BQ 8 1/2 R1 R5 9 R6 OP213 100kΩ 10 2.1kΩ 27.4Ω
41 0
4 6 11 12 13 7
6-
+10V R
28
+ G = 2127.4Ω 10µF
00
R3
Figure 42. Single Supply Strain Gage Amplifier
17.2kΩ R4 350Ω 0.1% 500Ω CMRR TRIM LOAD A HIGH ACCURACY LINEARIZED RTD 10-TURN CELL T.C. LESS THAN 50ppm/°C THERMOMETER AMPLIFIER 6 – 100mV A1 7 F.S. OUTPUT
Zero suppressing the bridge facilitates simple linearization of
5 + 4 0 10V 1/2 FS OP213
the resistor temperature device (RTD) by feeding back a small
–15V
amount of the output signal to the RTD. In Figure 43, the left
R1 R2
40 leg of the bridge is servoed to a virtual ground voltage by
17.2kΩ 301Ω
0 6-
0.1% 0.1%
28 Amplifier A1, and the right leg of the bridge is servoed to 0 V 00 Figure 41. Precision Load-Cell Scale Amplifier by Amplifier A2. This eliminates any error resulting from common-mode voltage change in the amplifier. A 3-wire RTD
A LOW VOLTAGE, SINGLE SUPPLY STRAIN GAGE
is used to balance the wire resistance on both legs of the bridge,
AMPLIFIER
thereby reducing temperature mismatch errors. The 5 V bridge The true zero swing capability of the OPx13 family allows the excitation is derived from the extremely stable AD588 reference amplifier in Figure 42 to amplify the strain gage bridge device with 1.5 ppm/°C drift performance. accurately even with no signal input while being powered by a Linearization of the RTD is done by feeding a fraction of the single 5 V supply. A stable 4 V bridge voltage is made possible output voltage back to the RTD in the form of a current. With by the rail-to-rail OP295 amplifier, whose output can swing to just the right amount of positive feedback, the amplifier output within a millivolt of either rail. This high voltage swing greatly will be linearly proportional to the temperature of the RTD. increases the bridge output signal without a corresponding increase in bridge input. Rev. F | Page 14 of 24 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 PHASE REVERSAL OP113 OFFSET ADJUST APPLICATION CIRCUITS A HIGH PRECISION INDUSTRIAL LOAD-CELL SCALE AMPLIFIER A LOW VOLTAGE, SINGLE SUPPLY STRAIN GAGE AMPLIFIER A HIGH ACCURACY LINEARIZED RTD THERMOMETER AMPLIFIER A HIGH ACCURACY THERMOCOUPLE AMPLIFIER AN ULTRALOW NOISE, SINGLE SUPPLY INSTRUMENTATION AMPLIFIER SUPPLY SPLITTER CIRCUIT LOW NOISE VOLTAGE REFERENCE 5 V ONLY STEREO DAC FOR MULTIMEDIA LOW VOLTAGE HEADPHONE AMPLIFIERS LOW NOISE MICROPHONE AMPLIFIER FOR MULTIMEDIA PRECISION VOLTAGE COMPARATOR OUTLINE DIMENSIONS ORDERING GUIDE