link to page 29 link to page 7 link to page 8 link to page 8 link to page 8 AD8421Data SheetARM GradeBRM GradeTest Conditions/ParameterCommentsMin TypMax Min Typ Max Unit Offset RTI vs. Supply (PSR) VS = ±2.5 V to ±18 V G = 1 90 120 100 120 dB G = 10 110 120 120 140 dB G = 100 124 130 140 150 dB G = 1000 130 140 140 150 dB INPUT CURRENT Input Bias Current 1 2 0.1 1 nA Over Temperature TA = −40°C to +85°C 8 6 nA Average TC 50 50 pA/°C Input Offset Current 0.5 2 0.1 1 nA Over Temperature TA = −40°C to +85°C 3 1.5 nA Average TC 1 1 pA/°C DYNAMIC RESPONSE Small Signal Bandwidth −3 dB G = 1 10 10 MHz G = 10 10 10 MHz G = 100 2 2 MHz G = 1000 0.2 0.2 MHz Settling Time 0.01% 10 V step G = 1 0.7 0.7 μs G = 10 0.4 0.4 μs G = 100 0.6 0.6 μs G = 1000 5 5 μs Settling Time 0.001% 10 V step G = 1 1 1 μs G = 10 0.6 0.6 μs G = 100 0.8 0.8 μs G = 1000 6 6 μs Slew Rate G = 1 to 100 35 35 V/μs GAIN3 G = 1 + (9.9 kΩ/RG) Gain Range 1 10,000 1 10,000 V/V Gain Error VOUT = ±10 V G = 1 0.05 0.02 % G = 10 to 1000 0.3 0.2 % Gain Nonlinearity VOUT = −10 V to +10 V G = 1 RL ≥ 2 kΩ 1 1 ppm RL = 600 Ω 1 3 1 3 ppm G = 10 to 1000 RL ≥ 600 Ω 30 50 30 50 ppm VOUT = −5 V to +5 V 5 10 5 10 ppm Gain vs. Temperature3 G = 1 5 0.1 1 ppm/°C G > 1 −50 −50 ppm/°C INPUT Input Impedance Differential 30||3 30||3 GΩ||pF Common Mode 30||3 30||3 GΩ||pF Input Operating Voltage VS = ±2.5 V to ±18 V −VS + 2.3 +VS − 1.8 −VS + 2.3 +VS − 1.8 V Range4 Over Temperature TA = −40°C −VS + 2.5 +VS − 2.0 −VS + 2.5 +VS − 2.0 V TA = +85°C −VS + 2.1 +VS − 1.8 −VS + 2.1 +VS − 1.8 V Rev. 0 | Page 6 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