Datasheet AD7796, AD7797 (Analog Devices) - 9

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Data Sheet AD7796/AD7797 RMS NOISE AND RESOLUTION SPECIFICATIONS
Table 6 shows the rms noise of the AD7796/AD7797 for some
Table 7. Typical Resolution (Bits) vs. Output Update Rate for
of the update rates. The numbers given are for the bipolar input
the AD7797 U sing a 2.5 V Reference
range with an external 2.5 V reference. These numbers are typical
Update Rate (Hz) Effective Bits (p-p)
and are generated with a differential input voltage of 0 V. Table 7 4.17 19 (16.5) and Table 8 show the effective resolution, while the output 6.25 19 (16.5) peak-to-peak (p-p) resolution is shown in parentheses. It is 8.33 19 (16) important to note that the effective resolution is calculated using the rms noise, while the p-p resolution is based on the p-p 10 18.5 (16) noise. The p-p resolution represents the resolution for which 12.5 18.5 (16) there is no code flicker. These numbers are typical and are 16.7 18.5 (15.5) rounded to the nearest 0.5 LSB. 33.2 18 (15) 50 17.5 (15)
Table 6. RMS Noise (µV) vs. Output Update Rate for the
62 17.5 (14.5)
AD7796/ AD7797 U sing a 2.5 V Reference
123 16.5 (13.5)
Update Rate (Hz) RMS Noise (µV) Table 8. Typical Resolution (Bits) vs. Output Update Rate for
4.17 0.065
the AD7796 U sing a 2.5 V Reference
6.25 0.07
Update Rate (Hz) Effective Bits (p-p)
8.33 0.08 4.17 16 (16) 10 0.09 6.25 16 (16) 12.5 0.1 8.33 16 (16) 16.7 0.12 10 16 (16) 33.2 0.17 50 0.21 12.5 16 (16) 62 0.23 16.7 16 (15.5) 123 0.43 33.2 16 (15) 50 16 (15) 62 16 (14.5) 123 16 (13.5) Rev. B | Page 9 of 24 Document Outline FEATURES INTERFACE APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS TIMING CHARACTERISTICS TIMING DIAGRAMS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS RMS NOISE AND RESOLUTION SPECIFICATIONS TYPICAL PERFORMANCE CHARACTERISTICS ON-CHIP REGISTERS COMMUNICATION REGISTER RS2, RS1, RS0 = 0, 0, 0 STATUS REGISTER RS2, RS1, RS0 = 0, 0, 0; Power-On/Reset = 0x80 MODE REGISTER RS2, RS1, RS0 = 0, 0, 1; Power-On/Reset = 0x000A CONFIGURATION REGISTER RS2, RS1, RS0 = 0, 1, 0; Power-On/Reset = 0x0710 DATA REGISTER RS2, RS1, RS0 = 0, 1, 1; Power-On/Reset = 0x0000 (AD7796)/0x000000 (AD7797) ID REGISTER RS2, RS1, RS0 = 1, 0, 0; Power-On/Reset = 0x5A (AD7796)/0x5B (AD7797) OFFSET REGISTER RS2, RS1, RS0 = 1, 1, 0; Power-On/Reset = 0x8000 (AD7796)/0x800000 (AD7797) FULL-SCALE REGISTER RS2, RS1, RS0 = 1, 1, 1; Power-On/Reset = 0x5XXX (AD7796)/0x5XXX00 (AD7797) ADC CIRCUIT INFORMATION OVERVIEW DIGITAL INTERFACE Single Conversion Mode Continuous Conversion Mode Continuous Read Mode CIRCUIT DESCRIPTION ANALOG INPUT CHANNEL BIPOLAR/UNIPOLAR CONFIGURATION DATA OUTPUT CODING REFERENCE RESET BURNOUT CURRENTS AVDD MONITOR TEMPERATURE MONITOR CALIBRATION GROUNDING AND LAYOUT APPLICATIONS INFORMATION WEIGH SCALES OUTLINE DIMENSIONS ORDERING GUIDE