Datasheet AD7798, AD7799 (Analog Devices) - 10

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AD7798/AD7799 Data Sheet OUTPUT NOISE AND RESOLUTION SPECIFICATIONS AD7798
Table 5 shows the AD7798 output rms noise for some update the effective resolution is calculated using the rms noise, whereas rates and gain settings. The numbers given are for the bipolar the peak-to-peak resolution is based on the peak-to-peak noise. input range with a 2.5 V reference. These numbers are typical The peak-to-peak resolution represents the resolution for which and are generated with a differential input voltage of 0 V. Table 6 there is no code flicker. These numbers are typical and are shows the effective resolution, and the output peak-to-peak rounded to the nearest LSB. resolution is shown in parentheses. It is important to note that
Table 5. Output RMS Noise (µV) vs. Gain and Output Update Rate for the AD7798 Using a 2.5 V Reference Update Rate Gain of 1 Gain of 2 Gain of 4 Gain of 8 Gain of 16 Gain of 32 Gain of 64 Gain of 128
4.17 Hz 0.64 0.6 0.29 0.22 0.1 0.065 0.039 0.041 8.33 Hz 1.04 0.96 0.38 0.26 0.13 0.078 0.057 0.055 16.7 Hz 1.55 1.45 0.54 0.36 0.18 0.11 0.087 0.086 33.2 Hz 2.3 2.13 0.74 0.5 0.23 0.17 0.124 0.118 62 Hz 2.95 2.85 0.92 0.58 0.29 0.2 0.153 0.144 123 Hz 4.89 4.74 1.49 1 0.48 0.32 0.265 0.283 242 Hz 11.76 9.5 4.02 1.96 0.88 0.45 0.379 0.397 470 Hz 11.33 9.44 3.07 1.79 0.99 0.63 0.568 0.593
Table 6. Typical Resolution (Bits) vs. Gain and Output Update Rate for the AD7798 Using a 2.5 V Reference Update Rate Gain of 1 Gain of 2 Gain of 4 Gain of 8 Gain of 16 Gain of 32 Gain of 64 Gain of 128
4.17 Hz 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 8.33 Hz 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16.7 Hz 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 33.2 Hz 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 62 Hz 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (15.5) 123 Hz 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (16) 16 (15.5) 16 (14.5) 242 Hz 16 (16) 16 (15.5) 16 (15.5) 16 (15.5) 16 (16) 16 (16) 16 (15) 16 (14) 470 Hz 16 (16) 16 (15.5) 16 (16) 16 (16) 16 (15.5) 16 (15.5) 16 (14.5) 15.5 (13.5) Rev. B | Page 10 of 28 Document Outline Features Interface Applications Functional Block Diagram General Description Revision History Specifications Timing Characteristics Absolute Maximum Ratings ESD Caution Pin Configuration and Function Descriptions Output Noise and Resolution Specifications AD7798 AD7799 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 (AD7798)/0x88 (AD7799) 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(00) ID Register RS2, RS1, RS0 = 1, 0, 0; Power-On/Reset = 0xX8 (AD7798)/0xX9 (AD7799) IO Register RS2, RS1, RS0 = 1, 0, 1; Power-On/Reset = 0x00 Offset Register RS2, RS1, RS0 = 1, 1, 0; Power-On/Reset = 0x8000(AD7798)/0x800000 (AD7799) Full-Scale Register RS2, RS1, RS0 = 1, 1, 1; Power-On/Reset = 0x5XXX (AD7798)/0x5XXX00 (AD7799) ADC Circuit Information Overview Digital Interface Single-Conversion Mode Continuous-Conversion Mode Continuous Read Circuit Description Analog Input Channel Instrumentation Amplifier Bipolar/Unipolar Configuration Data Output Coding Burnout Currents Reference Reference Detect Reset AVDD Monitor Calibration Grounding and Layout Applications Information Weigh Scales Outline Dimensions Ordering Guide