AD622AN

AD622 AD | Alldatasheet

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Technical content

4 AD622

+V S R G –IN +IN –VS REV. C 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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. a Low Cost Instrumentation Amplifier AD622

FEATURES

Higher Performance than Two or Three Op Amp Design Unity Gain with No External Resistor Optional Gains with One External Resistor (Gain Range 2 to 1000) Wide Power Supply Range ( 62.6 V to 615 V) Available in 8-Lead PDIP and SOIC Low Power, 1.5 mA max Supply Current GOOD DC PERFORMANCE 0.15% Gain Accuracy (G = 1) 125 mV max Input Offset Voltage 1.0 mV/8C max Input Offset Drift 5 nA max Input Bias Current 66 dB min Common-Mode Rejection Ratio (G = 1) NOISE 12 nV/ ÖHz @ 1 kHz Input Voltage Noise 0.60 mV p-p Noise (0.1 Hz to 10 Hz, G = 10) EXCELLENT AC CHARACTERISTICS 800 kHz Bandwidth (G = 10) 10 ms Settling Time to 0.1% @ G = 1–100

1.2 V/ ms Slew Rate

APPLICATIONS

Low Cost Thermocouple Amplifier Industrial Process Controls Difference Amplifier Low Cost Data Acquisition PRODUCT DESCRIPTION The AD622 is a low cost, moderately accurate instrumentation amplifier that requires only one external resistor to set any gain between 2 and 1,000. Or for a gain of 1, no external resistor is required. The AD622 is a complete difference or subtracter amplifier “system” while providing superior linearity and common- mode rejection by incorporating precision laser trimmed resistors. The AD622 replaces low cost, discrete, two or three op amp instrumentation amplifier designs and offers good common- mode rejection, superior linearity, temperature stability, reliabil- ity, and board area consumption. The low cost of the AD622 eliminates the need to design discrete instrumentation amplifi- ers to meet stringent cost targets. While providing a lower cost solution, it also provides performance and space improvements. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 1999

AD622–SPECIFICATIONS AD622 Model Conditions Min Typ Max Units GAIN G = 1 + (50.5 k/R G) Gain Range 1 1000 Gain Error1 VOUT = – 10 V G = 1 0.05 0.15 % G = 10 0.2 0.50 % G = 100 0.2 0.50 % G = 1000 0.2 0.50 % Nonlinearity, V OUT = – 10 V G = 1–1000 R L = 10 kW 10 ppm G = 1–100 R L = 2 kW 10 ppm Gain vs. Temperature Gain = 1 10 ppm/ °C Gain >11 –50 ppm/ °C VOLTAGE OFFSET (Total RTI Error = V OSI + VOSO/G) Input Offset, VOSI VS = – 5 V to – 15 V 60 125 mV Average TC V S = – 5 V to – 15 V 1.0 mV/°C Output Offset, V OSO VS = – 5 V to – 15 V 600 1500 mV Average TC V S = – 5 V to – 15 V 15 mV/°C Offset Referred to the Input vs. Supply (PSR) V S = – 5 V to – 15 V G = 1 80 100 dB G = 10 95 120 dB G = 100 110 140 dB G = 1000 110 140 dB INPUT CURRENT Input Bias Current 2.0 5.0 nA Average TC 3.0 pA/ °C Input Offset Current 0.7 2.5 nA Average TC 2.0 pA/ °C INPUT Input Impedance Differential 10i2G W ipF Common-Mode 10i2G W ipF Input Voltage Range 2 VS = – 2.6 V to – 5 V –V S + 1.9 +V S – 1.2 V Over Temperature –V S + 2.1 +V S – 1.3 V VS = – 5 V to – 18 V –V S + 1.9 +V S – 1.4 V Over Temperature –V S + 2.1 +V S – 1.4 V Common-Mode Rejection Ratio DC to 60 Hz with 1 kW Source Imbalance V CM = 0 V to – 10 V G = 1 66 78 dB G = 10 86 98 dB G = 100 103 118 dB G = 1000 103 118 dB OUTPUT Output Swing R L = 10 kW , VS = – 2.6 V to – 5 V –V S + 1.1 +V S – 1.2 V Over Temperature –V S + 1.4 +V S – 1.3 V VS = – 5 V to – 18 V –V S + 1.2 +V S – 1.4 V Over Temperature –V S + 1.6 +V S – 1.5 V Short Current Circuit – 18 mA (typical @ +258C, VS = 615 V, and RL = 2 kV unless otherwise noted) REV. C–2–

Model Conditions Min Typ Max Units DYNAMIC RESPONSE Small Signal –3 dB Bandwidth G = 1 1000 kHz G = 10 800 kHz G = 100 120 kHz G = 1000 12 kHz Slew Rate 1.2 V/ ms Settling Time to 0.1% 10 V Step G = 1–100 10 ms NOISE Voltage Noise, 1 kHz Total RTI Noise = (e2 ni ) + (eno / G)2 Input, Voltage Noise, e ni 12 nV/ ÖHz Output, Voltage Noise, e no 72 nV/ ÖHz RTI, 0.1 Hz to 10 Hz G = 1 4.0 mV p-p G = 10 0.6 mV p-p G = 100–1000 0.3 mV p-p Current Noise f = 1 kHz 100 fA/ ÖHz

0.1 Hz to 10 Hz 10 pA p-p

IIN VIN+, VREF = 0 +50 +60 mA Voltage Range –V S + 1.6 +V S – 1.6 V Gain to Output 1 – 0.0015 POWER SUPPLY Operating Range 3 – 2.6 – 18 V Quiescent Current V S = – 2.6 V to – 18 V 0.9 1.3 mA Over Temperature 1.1 1.5 mA TEMPERATURE RANGE For Specified Performance –40 to +85 °C NOTES 1Does not include effects of external resistor R G. 2One input grounded. G = 1. 3This is defined as the same supply range that is used to specify PSR. Specifications subject to change without notice. REV. C –3– AD622

Figure 3. Change in Input Offset Voltage vs. Warm-Up Figure 4. Voltage Noise Spectral Density vs. Frequency, Figure 5. Current Noise Spectral Density vs. Frequency

100 CMR – dB

Figure 6. CMR vs. Frequency, RTI, Zero to 1 k W Source

tracking of circuit components, thus insuring its performance. single-ended output referred to the REF pin potential. ductance increases asymptotically to that of the input transistors. accurately with a single external resistor. plify a 0–20 mA signal from the AD694 current transmitter. calculate the effect various error sources have on circuit accuracy. trimmed or hand selected to give high common-mode rejection. inputs, both contributing to the overall noise. Figure 14. Make vs. Buy

REV. C–8– Table I. Make vs. Buy Error Budget Total Error Total Error in ppm in ppm AD622 Circuit “Homebrew” Circuit Relative to 1 V FS Relative to 1 V FS Error Source Calculation Calculation AD622 Homebrew ABSOLUTE ACCURACY at TA = +25°C Total RTI Offset Voltage, mV 250 mV + 1500 mV/10 800 mV · 2 400 1600 Input Offset Current, nA 2.5 nA · 1k W 15 nA · 1 kW 2.5 15 CMR, dB 86 dB fi 50 ppm · 0.5 V (0.1% Match · 0.5 V)/10 V 25 50 Total Absolute Error 427.5 1665 DRIFT TO +85°C Gain Drift, ppm/°C (50 ppm + 5 ppm) · 60°C (50 ppm)/ °C · 60°C 3300 3000 Total RTI Offset Voltage, mV/°C( 2 mV/°C + 15 mV/°C/10) · 60°C9 mV/°C · 2 · 60°C 210 1080 Input Offset Current, pA/°C 2 pA/ °C · 1k W · 60°C 155 pA/ °C · 1k W · 60°C 0.12 9.3 Total Drift Error 3510.12 4089.3 RESOLUTION Gain Nonlinearity, ppm of Full Scale 10 ppm 20 ppm 10 20 Total Resolution Error 10.6 20.778 Grand Total Error 3948 5575 GAIN SELECTION The AD622’s gain is resistor programmed by RG, or more pre- cisely, by whatever impedance appears between Pins 1 and 8. The AD622 is designed to offer gains as close as possible to popular integer values using standard 1% resistors. Table II shows required values of R G for various gains. Note that for G = 1, the RG pins are unconnected (R G = ¥ ). For any arbitrary gain R G can be calculated by using the formula RG = 50.5 kW G - 1 To minimize gain error avoid high parasitic resistance in series with R G, and to minimize gain drift, R G should have a low TC—less than 10 ppm/ °C for the best performance. Table II. Required Values of Gain Resistors Desired 1% Std Table Calculated Gain Value of R G, V Gain 2 51.1 k 1.988 5 12.7 k 4.976 10 5.62 k 9.986 20 2.67 k 19.91 33 1.58 k 32.96 40 1.3 k 39.85 50 1.02 k 50.50 65 787 65.17 100 511 99.83 200 255 199.0 500 102 496.1 1000 51.1 989.3

Figure 15. RFI Suppression Circuit for AD622 Series In-Amps the –3 dB signal BW of this circuit is approximately 400 Hz. RTI and RF rejection better than 70 dB. kept to a minimum for optimum CMR.

REV. C –11– OUTLINE DIMENSIONS Dimensions shown in inches and (mm). Plastic DIP (N-8) Package 0.430 (10.92) 0.348 (8.84) 0.280 (7.11) 0.240 (6.10) PIN 1 SEATING PLANE0.022 (0.558) 0.014 (0.356) 0.060 (1.52) 0.015 (0.38) 0.210 (5.33) MAX 0.130 (3.30) MIN 0.070 (1.77) 0.045 (1.15) 0.100 (2.54) BSC 0.160 (4.06) 0.115 (2.93) 0.325 (8.25) 0.300 (7.62) 0.015 (0.381) 0.008 (0.204) 0.195 (4.95) 0.115 (2.93) SOIC (SO-8) Package 0.1968 (5.00) 0.1890 (4.80) 8 5 0.2440 (6.20) 0.2284 (5.80) PIN 1 0.1574 (4.00) 0.1497 (3.80) 0.0688 (1.75) 0.0532 (1.35)SEATING PLANE 0.0098 (0.25) 0.0040 (0.10) 0.0192 (0.49) 0.0138 (0.35) 0.0500 (1.27) BSC 0.0098 (0.25) 0.0075 (0.19) 0.0500 (1.27) 0.0160 (0.41) 0.0196 (0.50) 0.0099 (0.25)x 45° C2118c–0–4/99PRINTED IN U.S.A.