Datasheet AD623 (Analog Devices) - 16

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AD623 APPLICATIONS INFORMATION BASIC CONNECTION
The input voltage, which can be either single-ended (tie either Figure 42 and Figure 43 show the basic connection circuits for −IN or +IN to ground), or differential is amplified by the the AD623. The +V programmed gain. The output signal appears as the voltage S and −VS terminals are connected to the power supply. The supply can be either bipolar (V difference between the OUTPUT pin and the externally applied S = ±2.5 V to ±6 V) or single supply (−V voltage on the REF input. For a ground-referenced output, REF S = 0 V, +VS = 3.0 V to 12 V). Power supplies should be capacitively decoupled close to the power pins of should be grounded. the device. For the best results, use surface-mount 0.1 μF ceramic
GAIN SELECTION
chip capacitors and 10 μF electrolytic tantalum capacitors. The gain of the AD623 is resistor programmed by RG, or more
+VS
precisely, by whatever impedance appears between Pin 1 and
0.1µF 10µF
Pin 8. The AD623 is designed to offer accurate gains using 0.1% to 1% tolerance resistors. Table 5 shows the required values of
+2.5V TO +6V
RG for the various gains. Note that for G = 1, the RG terminals
RG V R
are unconnected (RG = ∞). For any arbitrary gain, RG can be
IN G OUTPUT VOUT R REF G
calculated by
REF (INPUT)
RG = 100 kΩ/(G − 1)
0.1µF 10µF REFERENCE TERMINAL
42 0
–VS
8-
–2.5V TO –6V
077 0 The reference terminal potential defines the zero output voltage Figure 42. Dual-Supply Basic Connection and is especially useful when the load does not share a precise
+VS
ground with the rest of the system. It provides a direct means of
0.1µF 10µF
injecting a precise offset to the output. The reference terminal is also useful when bipolar signals are being amplified because it
+3V TO +12V
can be used to provide a virtual ground voltage. The voltage on
RG
the reference terminal can be varied from −VS to +VS.
V R IN G OUTPUT VOUT R REF G REF (INPUT)
55 0 8- 77 00 Figure 43. Single-Supply Basic Connection
Table 5. Required Values of Gain Resistors Desired Gain 1% Standard Table Value of RG (Ω) Calculated Gain Using 1% Resistors
2 100 k 2 5 24.9 k 5.02 10 11 k 10.09 20 5.23 k 20.12 33 3.09 k 33.36 40 2.55 k 40.21 50 2.05 k 49.78 65 1.58 k 64.29 100 1.02 k 99.04 200 499 201.4 500 200 501 1000 100 1001 Rev. D | Page 16 of 24 Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION CONNECTION DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS SINGLE SUPPLY DUAL SUPPLIES BOTH DUAL AND SINGLE SUPPLIES ABSOLUTE MAXIMUM RATINGS ESD CAUTION TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION APPLICATIONS INFORMATION BASIC CONNECTION GAIN SELECTION REFERENCE TERMINAL INPUT AND OUTPUT OFFSET VOLTAGE INPUT PROTECTION RF INTERFERENCE GROUNDING Ground Returns for Input Bias Currents Output Buffering Single-Supply Data Acquisition System Amplifying Signals with Low Common-Mode Voltage INPUT DIFFERENTIAL AND COMMON-MODE RANGE vs. SUPPLY AND GAIN OUTLINE DIMENSIONS ORDERING GUIDE