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CONNECTION DIAGRAM

8-Lead Plastic Mini-DIP (N), Cerdip (Q)

and SOIC (R) Packages

–IN

–V

+IN

OUTPUT

REF

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 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.

Low Cost, Low Power

Instrumentation Amplifier

AD620

FEATURES

EASY TO USE

Gain Set with One External Resistor

(Gain Range 1 to 1000)

Wide Power Supply Range (62.3 V to 618 V)

Higher Performance than Three Op Amp IA Designs

Available in 8-Lead DIP and SOIC Packaging

Low Power, 1.3 mA max Supply Current

EXCELLENT DC PERFORMANCE (“B GRADE”)

50 mV max, Input Offset Voltage

0.6 mV/8C max, Input Offset Drift

1.0 nA max, Input Bias Current

100 dB min Common-Mode Rejection Ratio (G = 10)

LOW NOISE

9 nV/√Hz, @ 1 kHz, Input Voltage Noise

0.28 mV p-p Noise (0.1 Hz to 10 Hz)

EXCELLENT AC SPECIFICATIONS

120 kHz Bandwidth (G = 100)

15 ms Settling Time to 0.01%

APPLICATIONS

Weigh Scales

ECG and Medical Instrumentation

Transducer Interface

Data Acquisition Systems

Industrial Process Controls

Battery Powered and Portable Equipment

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700 World Wide Web Site: http://www.analog.com

Fax: 781/326-8703 © Analog Devices, Inc., 1999

PRODUCT DESCRIPTION

The AD620 is a low cost, high accuracy instrumentation ampli-

fier that requires only one external resistor to set gains of 1 to

0 5 10 15 20

30,000

5,000

10,000

15,000

20,000

25,000

TOTAL ERROR, PPM OF FULL SCALE

SUPPLY CURRENT – mA

AD620A

3 OP-AMP

IN-AMP

(3 OP-07s)

Figure 1. Three Op Amp IA Designs vs. AD620

SOURCE RESISTANCE – V

100M10k1k 10M1M100k

10,000

0.1

100

1,000

RTI VOLTAGE NOISE

(0.1 – 10Hz) – mV p-p

TYPICAL STANDARD

BIPOLAR INPUT

IN-AMP

AD620 SUPERbETA

BIPOLAR INPUT

IN-AMP

G = 100

Figure 2. Total Voltage Noise vs. Source Resistance

1000. Furthermore, the AD620 features 8-lead SOIC and DIP

packaging that is smaller than discrete designs, and offers lower

power (only 1.3 mA max supply current), making it a good fit

for battery powered, portable (or remote) applications.

The AD620, with its high accuracy of 40 ppm maximum

nonlinearity, low offset voltage of 50 µV max and offset drift of

0.6 µV/°C max, is ideal for use in precision data acquisition

systems, such as weigh scales and transducer interfaces. Fur-

thermore, the low noise, low input bias current, and low power

of the AD620 make it well suited for medical applications such

as ECG and noninvasive blood pressure monitors.

The low input bias current of 1.0 nA max is made possible with

the use of Superβeta processing in the input stage. The AD620

works well as a preamplifier due to its low input voltage noise of

9 nV/√Hz at 1 kHz, 0.28 µV p-p in the 0.1 Hz to 10 Hz band,

0.1 pA/√Hz input current noise. Also, the AD620 is well suited

for multiplexed applications with its settling time of 15 µs to

0.01% and its cost is low enough to enable designs with one in-

amp per channel.

1 2 3 4 5 6 ... 15 16

Sommario

Pagina 1 - Instrumentation Amplifier

CONNECTION DIAGRAM8-Lead Plastic Mini-DIP (N), Cerdip (Q)and SOIC (R) Packages–INRG–VS+INRG+VSOUTPUTREF12348765AD620TOP VIEWREV. EInformation furnishe

Pagina 2 - AD620–SPECIFICATIONS

AD620REV. E–10–VB–VSA1 A2A3C2RGR1R2GAINSENSEGAINSENSER3400V10kV10kVI2I110kVREF10kV+IN– IN20mA20mAR4400VOUTPUTC1Q2Q1Figure 33. Simplified Schematic of

Pagina 3

AD620REV. E–11–Make vs. Buy: A Typical Bridge Application Error BudgetThe AD620 offers improved performance over “homebrew”three op amp IA designs, al

Pagina 4 - WARNING!

AD620REV. E–12–3kV+5VDIGITALDATAOUTPUTADCREFINAGND20kV10kV20kVAD620BG=1001.7mA 0.10mA0.6mAMAX499V3kV3kV3kV218376541.3mAMAXAD705Figure 35. A Pressure M

Pagina 5 - Typical Characteristics

AD620REV. E–13–Precision V-I ConverterThe AD620, along with another op amp and two resistors, makesa precision current source (Figure 37). The op amp

Pagina 6 - AD620–Typical Characteristics

AD620REV. E–14–COMMON-MODE REJECTIONInstrumentation amplifiers like the AD620 offer high CMR,which is a measure of the change in output voltage when b

Pagina 7 - BW LIMIT

AD620REV. E–15–GROUND RETURNS FOR INPUT BIAS CURRENTSInput bias currents are those currents necessary to bias the inputtransistors of an amplifier. Th

Pagina 8

AD620REV. E–16–OUTLINE DIMENSIONSDimensions shown in inches and (mm).Plastic DIP (N-8) Package81450.430 (10.92)0.348 (8.84)0.280 (7.11)0.240 (6.10)PIN

Pagina 9 - SETTLING TIME – ms

AD620–SPECIFICATIONS(Typical @ +258C, VS = 615 V, and RL = 2 kV, unless otherwise noted) AD620A AD620B AD620S1Model Conditions Min Typ Max Min Typ Ma

Pagina 10 - THEORY OF OPERATION

AD620AD620A AD620B AD620S1Model Conditions Min Typ Max Min Typ Max Min Typ Max UnitsDYNAMIC RESPONSESmall Signal –3 dB BandwidthG = 1 1000 1000 1000 k

Pagina 11 - Figure 34. Make vs. Buy

AD620REV. E–4–NOTES1Stresses above those listed under Absolute Maximum Ratings may cause perma-nent damage to the device. This is a stress rating on

Pagina 12 - Medical ECG

AD620REV. E–5–Typical Characteristics(@ +258C, VS = 615 V, RL = 2 kV, unless otherwise noted)INPUT OFFSET VOLTAGE – mV20304050–40 0 +40 +80PERCENTAGE

Pagina 13 - (Operates on 1.8 mA

AD620–Typical Characteristics FREQUENCY – Hz1000100101101000100CURRENT NOISE – fA/!HzFigure 9. Current Noise Spectral Density vs. FrequencyRTI NOISE –

Pagina 14 - GROUNDING

AD620REV. E–7–FREQUENCY – HzPSR – dB1601M80401600.1140100120100k10k1k1001020G = 1000 G = 100G = 10G = 1180Figure 14. Positive PSR vs. Frequency, RTI (

Pagina 15 - Thermocouple Inputs

AD620REV. E–8–OUTPUT VOLTAGE SWING – Volts p-pLOAD RESISTANCE – V300010k2010100 1kVS = 615VG = 10Figure 20. Output Voltage Swing vs. Load Resistance..

Pagina 16 - SOIC (SO-8) Package

AD620REV. E–9–....................Figure 26. Small Signal Pulse Response, G = 100,RL = 2 k

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