AD8421Data SheetTYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, VS = ±15 V, VREF = 0 V, RL = 2 kΩ, unless otherwise noted. 600600500500400400S TS300ITUNI300UN20020010010000–60–40–200204060 03 0 –400–300–200–1000100200300400 006 3- INPUT OFFSET VOLTAGE (µV) 23- OUTPUT OFFSET VOLTAGE (µV) 101 012 1 Figure 4. Typical Distribution of Input Offset Voltage Figure 7. Typical Distribution of Output Offset Voltage 18001200150010001200800S ITS900IT600UNUN6004003002000–2.0 –1.5 –1.0 –0.500.51.01.52.00 004 –2.0–1.5–1.0–0.500.51.01.52.0 007 INPUT BIAS CURRENT (nA) 10123- INPUT OFFSET CURRENT (nA) 123- 10 Figure 5. Typical Distribution of Input Bias Current Figure 8. Typical Distribution of Input Offset Current 1600140014001200120010001000S800ITS IT800UNUN6006004004002002000–20 –15 –10–505101520 005 0–120–90–60–300306090120 08 -0 PSRR (µV/V) 10123- CMRR (µV/V) 123 10 Figure 6. Typical Distribution of PSRR (G = 1) Figure 9. Typical Distribution of CMRR (G = 1) Rev. 0 | Page 10 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