AD621| Datasheet

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a
FEATURES EASY TO USE Pin-Strappable Gains of 10 and 100 All Errors Specified for Total System Performance Higher Performance than Discrete In Amp Designs Available in 8-Lead DIP and SOIC Low Power, 1.3 mA Max Supply Current Wide Power Supply Range ( 2.3 V to 18 V) EXCELLENT DC PERFORMANCE 0.15% Max, Total Gain Error 5 ppm/ C, Total Gain Drift 125 V Max, Total Offset Voltage 1.0 V/ C Max, Offset Voltage Drift LOW NOISE 9 nV/Hz, @ 1 kHz, Input Voltage Noise 0.28 V p-p Noise (0.1 Hz to 10 Hz) EXCELLENT AC SPECIFICATIONS 800 kHz Bandwidth (G = 10), 200 kHz (G = 100) 12 s Settling Time to 0.01% APPLICATIONS Weigh Scales Transducer Interface and Data Acquisition Systems Industrial Process Controls Battery-Powered and Portable Equipment PRODUCT DESCRIPTION

Low Drift, Low Power Instrumentation Amplifier AD621
CONNECTION DIAGRAM 8-Lead Plastic Mini-DIP (N), Cerdip (Q) and SOIC (R) Packages

G = 10/100 1 IN 2 +IN 3

G = 10/100 +VS

AD621

TOP VIEW 6 OUTPUT (Not to Scale) 5 REF VS 4

gain drift errors are achieved by the use of internal gain setting resistors. Fixed gains of 10 and 100 can easily be set via external pin strapping. The AD621 is fully specified as a total system, therefore, simplifying the design process. For portable or remote applications, where power dissipation, size, and weight are critical, the AD621 features a very low supply current of 1.3 mA max and is packaged in a compact 8-lead SOIC, 8-lead plastic DIP or 8-lead cerdip. The AD621 also excels in applications requiring high total accuracy, such as precision data acquisition systems used in weigh scales and transducer interface circuits. Low maximum error specifications including nonlinearity of 10 ppm, gain drift of 5 ppm/ C, 50 uV offset voltage, and 0.6 uV/ C offset drift ("B" grade), make possible total system performance at a lower cost than has been previously achieved with discrete designs or with other monolithic instrumentation amplifiers. When operating from high source impedances, as in ECG and blood pr
essure monitors, the AD621 features the ideal combination of low noise and low input bias currents. Voltage noise is specified as 9 nV/Hz at 1 kHz and 0.28 uV p-p from 0.1 Hz to 10 Hz. Input current noise is also extremely low at 0.1 pA/Hz. The AD621 outperforms FET input devices with an input bias current specification of 1.5 nA max over the full industrial temperature range.
Vp-p

The AD621 is an easy to use, low cost, low power, high accuracy instrumentation amplifier that is ideally suited for a wide range of applications. Its unique combination of high performance, small size and low power, outperforms discrete in amp implementations. High functionality, low gain errors, and low
30,000

TOTAL ERROR, ppm OF FULL SCALE

25,000 3 OP AMP IN AMP (3 OP 07S)

10,000

20,000

TOTAL INPUT VOLTAGE NOISE, G = 100 (0.1 10Hz)

15,000

1,000 TYPICAL STANDARD BIPOLAR INPUT IN AMP

10,000

AD621A

100

5,000

10 AD621 SUPER ETA BIPOLAR INPUT IN AMP

10 SUPPLY CURRENT mA

Figure 1. Three Op Amp IA Designs vs. AD621

0.1 1k 10k 100k 1M SOURCE RESISTANCE 10M 100M

REV. B
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.

Figure 2. Total Voltage Noise vs. Source Resistance

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