Data SheetAD8421PIN CONFIGURATION AND FUNCTION DESCRIPTIONSAD8421–IN18+VSRG 27VOUTRG 36REF+IN45–VS 2 00 TOP VIEW(Not to Scale) 123- 10 Figure 3. Pin Configuration Table 5. Pin Function Descriptions Pin No.MnemonicDescription 1 −IN Negative Input Terminal. 2, 3 RG Gain Setting Terminals. Place resistor across the RG pins to set the gain. G = 1 + (9.9 kΩ/RG). 4 +IN Positive Input Terminal. 5 −VS Negative Power Supply Terminal. 6 REF Reference Voltage Terminal. Drive this terminal with a low impedance voltage source to level shift the output. 7 VOUT Output Terminal. 8 +VS Positive Power Supply Terminal. Rev. 0 | Page 9 of 28 Document Outline FEATURES APPLICATIONS PIN CONNECTION DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS AR AND BR GRADES ARM AND BRM GRADES ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS THEORY OF OPERATION ARCHITECTURE GAIN SELECTION RG Power Dissipation REFERENCE TERMINAL INPUT VOLTAGE RANGE LAYOUT Common-Mode Rejection Ratio over Frequency Power Supplies and Grounding Reference Pin INPUT BIAS CURRENT RETURN PATH INPUT VOLTAGES BEYOND THE SUPPLY RAILS Input Voltages Beyond the Maximum Ratings RADIO FREQUENCY INTERFERENCE (RFI) CALCULATING THE NOISE OF THE INPUT STAGE Source Resistance Noise Voltage Noise of the Instrumentation Amplifier Current Noise of the Instrumentation Amplifier Total Noise Density Calculation APPLICATIONS INFORMATION DIFFERENTIAL OUTPUT CONFIGURATION DRIVING AN ADC OUTLINE DIMENSIONS ORDERING GUIDE