Analog Devices AD620 manual

CONNECTION DIAGRAM 8-Lead Plastic Mini-DIP (N), Cerdip (Q) and SOIC (R) Packages –IN R G –V S +IN R G +V S OUTPUT REF 1 2 3 4 8 7 6 5 AD620 TOP VIEW 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 [...]

AD620–SPECIFICA TIONS (Typical @ +25 8 C, V S = 6 15 V, and R L = 2 k V , unless otherwise noted) AD620A AD620B AD620S 1 Model Conditions Min Typ Max Min Typ Max Min Typ Max Units GAIN G = 1 + (49.4 k/R G ) Gain Range 1 10,000 1 10,000 1 10,000 Gain Error 2 V OUT = ± 10 V G = 1 0.03 0.10 0.01 0.02 0.03 0.10 % G = 10 0.15 0.30 0.10 0.15 0.15 0.30[...]

AD620 AD620A AD620B AD620S 1 Model Conditions Min Typ Max Min Typ Max Min Typ Max Units DYNAMIC RESPONSE Small Signal –3 dB Bandwidth G = 1 1000 1000 1000 kHz G = 10 800 800 800 kHz G = 100 120 120 120 kHz G = 1000 12 12 12 kHz Slew Rate 0.75 1.2 0.75 1.2 0.75 1.2 V/ µ s Settling Time to 0.01% 10 V Step G = 1–100 15 15 15 µ s G = 1000 150 150[...]

AD620 REV. E –4– NOTES 1 Stresses above those listed under Absolute Maximum Ratings may cause perma- nent 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 rati[...]

AD620 REV. E –5– T ypical Characteristics (@ +25 8 C, V S = 6 15 V, R L = 2 k V , unless otherwise noted) INPUT OFFSET VOLTAGE – m V 20 30 40 50 –40 0 +40 +80 PERCENTAGE OF UNITS –80 SAMPLE SIZE = 360 10 0 Figure 3. Typical Distribution of Input Offset Voltage INPUT BIAS CURRENT – pA 0 10 20 30 40 50 –600 0 +600 PERCENTAGE OF UNITS ?[...]

AD620–T ypical Characteristics FREQUENCY – Hz 1000 100 10 1 10 1000 100 CURRENT NOISE – fA/ ! Hz Figure 9. Current Noise Spectral Density vs. Frequency RTI NOISE – 2.0 m V/DIV TIME – 1 SEC/DIV Figure 10a. 0.1 Hz to 10 Hz RTI Voltage Noise (G = 1) RTI NOISE – 0.1 m V/DIV TIME – 1 SEC/DIV Figure 10b. 0.1 Hz to 10 Hz RTI Voltage Noise (G[...]

AD620 REV. E –7– FREQUENCY – Hz PSR – dB 160 1M 80 40 1 60 0.1 140 100 120 100k 10k 1k 100 10 20 G = 1000 G = 100 G = 10 G = 1 180 Figure 14. Positive PSR vs. Frequency, RTI (G = 1–1000) FREQUENCY – Hz PSR – dB 160 1M 80 40 1 60 0.1 140 100 120 100k 10k 1k 100 10 20 180 G = 10 G = 100 G = 1 G = 1000 Figure 15. Negative PSR vs. Frequen[...]

AD620 REV. E –8– OUTPUT VOLTAGE SWING – Volts p-p LOAD RESISTANCE – V 30 0 0 10k 20 10 100 1k V S = 6 15V G = 10 Figure 20. Output Voltage Swing vs. Load Resistance .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... Figure 21. Large Signal Pulse Response and Settling Time G = 1 (0.5 mV = 0.01[...]

AD620 REV. E –9– .... .... .... .... .... .... .... .... ........ .... .... .... .... .... .... .... .... ........ Figure 26. Small Signal Pulse Response, G = 100, R L = 2 k Ω , C L = 100 pF .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... Figure 27. Large Signal Response and Settling Time, G[...]

AD620 REV. E –10– V B –V S A1 A2 A3 C2 R G R1 R2 GAIN SENSE GAIN SENSE R3 400 V 10k V 10k V I2 I1 10k V REF 10k V +IN – IN 20 m A 20 m A R4 400 V OUTPUT C1 Q2 Q1 Figure 33. Simplified Schematic of AD620 THEORY OF OPERATION The AD620 is a monolithic instrumentation amplifier based on a modification of the classic three op amp approach. Absol[...]

AD620 REV. E –11– Make vs. Buy: A Typical Bridge Application Error Budget The AD620 offers improved performance over “homebrew” three op amp IA designs, along with smaller size, fewer compo- nents and 10 × lower supply current. In the typical application, shown in Figure 34, a gain of 100 is required to amplify a bridge output of 20 mV ful[...]

AD620 REV. E –12– 3k V +5V DIGITAL DATA OUTPUT ADC REF IN AGND 20k V 10k V 20k V AD620B G=100 1.7mA 0.10mA 0.6mA MAX 499 V 3k V 3k V 3k V 2 1 8 3 7 6 5 4 1.3mA MAX AD705 Figure 35. A Pressure Monitor Circuit which Operates on a +5 V Single Supply Pressure Measurement Although useful in many bridge applications such as weigh scales, the AD620 is[...]

AD620 REV. E –13– Precision V-I Converter Th e AD620, along with an other op amp and tw o resistors, makes a precision current source (Figure 37). The op amp buffers the reference terminal to maintain good CMR. The output voltage V X of the AD620 appears across R1, which converts it to a curre nt. This current less only, the input bias current [...]

AD620 REV. E –14– COMMON-MODE REJECTION Instrumentation amplifiers like the AD620 offer high CMR, which is a measure of the change in output voltage when both inputs are changed by equal amounts. These specifications are usually given for a full-range input voltage change and a speci- fied source imbalance. For optimal CMR the reference termina[...]

AD620 REV. E –15– GROUND RETURNS FOR INPUT BIAS CURRENTS Input bias currents are those currents necessary to bias the input transistors of an amplifier. There must be a direct return path for these currents; therefore, when amplifying “floating” input V OUT AD620 – INPUT R G TO POWER SUPPLY GROUND REFERENCE + INPUT +V S –V S LOAD Figure[...]

AD620 REV. E –16– OUTLINE DIMENSIONS Dimensions shown in inches and (mm). Plastic DIP (N-8) Package 8 14 5 0.430 (10.92) 0.348 (8.84) 0.280 (7.11) 0.240 (6.10) PIN 1 SEATING PLANE 0.022 (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.[...]