link to page 21 link to page 22 link to page 9 link to page 9 AD8421Data SheetABSOLUTE MAXIMUM RATINGSTHERMAL RESISTANCETable 3. θ Parameter Rating JA is specified for a device in free air using a 4-layer JEDEC printed circuit board (PCB). Supply Voltage ±18 V Output Short-Circuit Current Duration Indefinite Table 4. Maximum Voltage at −IN or +IN1 −VS + 40 V Package θJA Unit Minimum Voltage at −IN or +IN +VS − 40 V 8-Lead SOIC 107.8 °C/W Maximum Voltage at REF2 +VS + 0.3 V 8-Lead MSOP 138.6 °C/W Minimum Voltage at REF −VS − 0.3 V Storage Temperature Range −65°C to +150°C Operating Temperature Range −40°C to +125°C ESD CAUTION Maximum Junction Temperature 150°C ESD Human Body Model 2 kV Charged Device Model 1.25 kV Machine Model 0.2 kV 1 For voltages beyond these limits, use input protection resistors. See the Theory of Operation section for more information. 2 There are ESD protection diodes from the reference input to each supply, so REF cannot be driven beyond the supplies in the same way that +IN and −IN can. See the Reference Terminal section for more information. Stresses above those listed under Absolute Maximum Ratings may cause permanent 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 rating conditions for extended periods may affect device reliability. Rev. 0 | Page 8 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