SBAS790C October   2018  – June 2019 ADS125H02

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Functional Block Diagram
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 Typical Characteristics
  8. 8 Parameter Measurement Information
    1. 8.1 Noise Performance
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Input Range
      2. 9.3.2 Analog Inputs
        1. 9.3.2.1 ESD Diodes
        2. 9.3.2.2 Input Multiplexer
          1. 9.3.2.2.1 Analog Inputs (AIN0, AIN1, AINCOM)
          2. 9.3.2.2.2 High-Voltage Power Supply Readback
          3. 9.3.2.2.3 Internal VCOM Connection (Default)
          4. 9.3.2.2.4 Temperature Sensor
      3. 9.3.3 Programmable Gain Amplifier (PGA)
        1. 9.3.3.1 PGA Operating Range
        2. 9.3.3.2 PGA Monitor
      4. 9.3.4 Reference Voltage
        1. 9.3.4.1 Internal Reference
        2. 9.3.4.2 External Reference
        3. 9.3.4.3 AVDD Power-Supply Reference
        4. 9.3.4.4 Reference Monitor
      5. 9.3.5 Current Sources (IDAC1 and IDAC2)
      6. 9.3.6 General-Purpose Inputs and Outputs (GPIOs)
      7. 9.3.7 ADC Modulator
      8. 9.3.8 Digital Filter
        1. 9.3.8.1 Sinc Filter Mode
          1. 9.3.8.1.1 Sinc Filter Frequency Response
        2. 9.3.8.2 FIR Filter
        3. 9.3.8.3 50-Hz and 60-Hz Normal Mode Rejection
    4. 9.4 Device Functional Modes
      1. 9.4.1 Conversion Control
        1. 9.4.1.1 Continuous-Conversion Mode
        2. 9.4.1.2 Pulse-Conversion Mode
        3. 9.4.1.3 Conversion Latency
        4. 9.4.1.4 Start-Conversion Delay
      2. 9.4.2 Auto-Zero Mode
      3. 9.4.3 Clock Mode
      4. 9.4.4 Reset
        1. 9.4.4.1 Power-On Reset
        2. 9.4.4.2 Reset by Pin
        3. 9.4.4.3 Reset by Command
      5. 9.4.5 Calibration
        1. 9.4.5.1 Offset and Full-Scale Calibration
          1. 9.4.5.1.1 Offset Calibration Registers
          2. 9.4.5.1.2 Full-Scale Calibration Registers
        2. 9.4.5.2 Offset Calibration (OFSCAL)
        3. 9.4.5.3 Full-Scale Calibration (GANCAL)
        4. 9.4.5.4 Calibration Command Procedure
        5. 9.4.5.5 User Calibration Procedure
    5. 9.5 Programming
      1. 9.5.1 Serial Interface
        1. 9.5.1.1 Chip-Select Pins (CS1 and CS2)
        2. 9.5.1.2 Serial Clock (SCLK)
        3. 9.5.1.3 Data Input (DIN)
        4. 9.5.1.4 Data Output/Data Ready (DOUT/DRDY)
      2. 9.5.2 Data Ready (DRDY)
        1. 9.5.2.1 DRDY in Continuous-Conversion Mode
        2. 9.5.2.2 DRDY in Pulse-Conversion Mode
        3. 9.5.2.3 Data Ready by Software Polling
      3. 9.5.3 Conversion Data
        1. 9.5.3.1 Status Byte (STATUS0)
        2. 9.5.3.2 Conversion Data Format
      4. 9.5.4 Cyclic Redundancy Check (CRC)
      5. 9.5.5 Commands
        1. 9.5.5.1  General Command Format
        2. 9.5.5.2  NOP Command
        3. 9.5.5.3  RESET Command
        4. 9.5.5.4  START Command
        5. 9.5.5.5  STOP Command
        6. 9.5.5.6  RDATA Command
        7. 9.5.5.7  OFSCAL Command
        8. 9.5.5.8  GANCAL Command
        9. 9.5.5.9  RREG Command
        10. 9.5.5.10 WREG Command
        11. 9.5.5.11 LOCK Command
        12. 9.5.5.12 UNLOCK Command
    6. 9.6 Register Map
      1. 9.6.1  Device Identification (ID) Register (address = 00h) [reset = 6xh]
        1. Table 30. ID Register Field Descriptions
      2. 9.6.2  Main Status (STATUS0) Register (address = 01h) [reset = 01h]
        1. Table 31. STATUS0 Register Field Descriptions
      3. 9.6.3  Mode 0 (MODE0) Register (address = 02h) [reset = 24h]
        1. Table 32. MODE0 Register Field Descriptions
      4. 9.6.4  Mode 1 (MODE1) Register (address = 03h) [reset = 01h]
        1. Table 33. MODE1 Register Field Descriptions
      5. 9.6.5  Mode 2 (MODE2) Register (address = 04h) [reset = 00h]
        1. Table 34. MODE2 Register Field Descriptions
      6. 9.6.6  Mode 3 (MODE3) Register (address = 05h) [reset = 00h]
        1. Table 35. MODE3 Register Field Descriptions
      7. 9.6.7  Reference Configuration (REF) Register (address = 06h) [reset = 05h]
        1. Table 36. REF Register Field Descriptions
      8. 9.6.8  Offset Calibration (OFCALx) Registers (address = 07h, 08h, 09h) [reset = 00h, 00h, 00h]
        1. Table 37. OFCAL0, OFCAL1, OFCAL2 Registers Field Description
      9. 9.6.9  Full-Scale Calibration (FSCALx) Registers (address = 0Ah, 0Bh, 0Ch) [reset = 00h, 00h, 40h]
        1. Table 38. FSCAL0, FSCAL1, FSCAL2 Registers Field Description
      10. 9.6.10 Current Source Multiplexer (I_MUX) Register (address = 0Dh) [reset = FFh]
        1. Table 39. I_MUX Register Field Descriptions
      11. 9.6.11 Current Source Magnitude (I_MAG) Register (address = 0Eh) [reset = 00h]
        1. Table 40. I_MAG Register Field Descriptions
      12. 9.6.12 Reserved (RESERVED) Register (address = 0Fh) [reset = 00h]
        1. Table 41. RESERVED Register Field Descriptions
      13. 9.6.13 MODE4 (MODE4) Register (address = 10h) [reset = 50h]
        1. Table 42. MODE4 Register Field Descriptions
      14. 9.6.14 PGA Alarm (STATUS1) Register (address = 11h) [reset = xxh]
        1. Table 43. STATUS1 Register Field Descriptions
      15. 9.6.15 Status 2 (STATUS2) Register (address = 12h) [reset = 0xh]
        1. Table 44. STATUS2 Register Field Descriptions
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Input Range
      2. 10.1.2 Input Overload
        1. 10.1.2.1 Input Signal Rate of Change (dV/dt)
      3. 10.1.3 Unused Inputs and Outputs
    2. 10.2 Typical Applications
      1. 10.2.1 ±10-V Analog Input Module
        1. 10.2.1.1 Design Requirements
        2. 10.2.1.2 Detailed Design Procedure
        3. 10.2.1.3 Application Curves
      2. 10.2.2 Thermocouple Input With High Common-Mode Voltage
    3. 10.3 Initialization Setup
  11. 11Power Supply Recommendations
    1. 11.1 Power-Supply Decoupling
    2. 11.2 Analog Power-Supply Clamp
    3. 11.3 Power-Supply Sequencing
    4. 11.4 5-V to ±15-V DC-DC Converter
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Documentation Support
      1. 13.1.1 Related Documentation
    2. 13.2 Receiving Notification of Documentation Updates
    3. 13.3 Community Resources
    4. 13.4 Trademarks
    5. 13.5 Electrostatic Discharge Caution
    6. 13.6 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.1 Noise Performance

Noise performance depends on the device configuration: data rate, input gain, digital filter mode, and auto-zero mode. Two significant factors affecting noise performance are data rate and input gain. Decreasing the data rate lowers the noise because the bandwidth is reduced over the fixed noise profile of the ADC. Increasing the gain reduces noise (when noise is treated as an input-referred quantity) because the noise of the PGA is lower than that of the ADC. Noise performance also depends on the digital filter and auto-zero mode. As the digital filter order increases, the bandwidth decreases, which results in lower noise. As a result of two-point data averaging in auto-zero mode, noise performance improves by √2 compared to the normal operating mode.

Table 1 lists the noise data of gain equal to 0.125 to 2 (corresponding input ranges of ±20 V to ±1.25 V) as input-referred values. Table 2 lists the noise data of gain equal to 4 to 128 (corresponding input ranges of ±625 mV to ±19.5 mV). The noise data are in units of µVRMS (RMS = root mean square) under the conditions listed. Values in parenthesis are peak-to-peak (µVpp).

The noise data represent typical ADC performance at TA = 25°C, 2.5-V reference voltage, and auto-zero mode disabled. The noise data are the standard deviation and peak-to-peak computations of the ADC data. The data are acquired with inputs shorted, based on consecutive ADC readings for a period of ten seconds or 8192 data points, whichever occurs first. Because of the statistical nature of noise, repeated measurements may yield higher or lower noise results. Similarly, longer periods of data acquisition may result in higher peak-to-peak noise results.

Table 1. Typical Noise (en) in µVRMS and (µVPP), Gain = 0.125 to 2, VREF = 2.5 V

DATA RATE (SPS) FILTER MODE GAIN (Full-Scale Range)
0.125 (±20 V) 0.1875 (±13.3 V) 0.25 (±10 V) 0.5 (±5 V) 1 (±2.5 V) 2 (±1.25 V)
2.5 FIR 1.3 (4.8) 0.89 (3.6) 0.69 (2.1) 0.49 (1.9) 0.37 (1.5) 0.17 (0.67)
2.5 Sinc1 1.1 (4.2) 0.6 (2.4) 0.57 (2.4) 0.39 (1.5) 0.29 (1) 0.15 (0.63)
2.5 Sinc2 1 (3.6) 0.68 (2) 0.44 (1.8) 0.32 (1) 0.26 (0.97) 0.12 (0.52)
2.5 Sinc3 1.1 (3) 0.67 (2) 0.49 (1.5) 0.32 (1) 0.24 (0.89) 0.11 (0.41)
2.5 Sinc4 0.98 (3.6) 0.64 (2) 0.48 (1.2) 0.3 (1) 0.26 (0.97) 0.11 (0.41)
5 FIR 1.7 (6.6) 1.2 (4.8) 0.93 (4.2) 0.57 (2.5) 0.45 (2) 0.24 (1.2)
5 Sinc1 1.5 (6.6) 0.98 (3.6) 0.77 (3.6) 0.53 (2.2) 0.4 (1.9) 0.2 (0.93)
5 Sinc2 1.3 (4.8) 0.91 (4) 0.68 (2.4) 0.44 (1.8) 0.35 (1.6) 0.18 (0.82)
5 Sinc3 1.2 (4.8) 0.83 (3.2) 0.62 (2.4) 0.39 (1.6) 0.3 (1.3) 0.16 (0.75)
5 Sinc4 1.2 (3.6) 0.75 (3.2) 0.54 (2.1) 0.38 (1.5) 0.27 (1.2) 0.14 (0.56)
10 FIR 2.4 (11) 1.6 (7.9) 1.2 (5.7) 0.82 (4.3) 0.69 (3.3) 0.34 (1.7)
10 Sinc1 1.9 (9.5) 1.4 (6.8) 1.1 (5.4) 0.7 (3.4) 0.55 (2.7) 0.3 (1.5)
10 Sinc2 1.7 (8.9) 1.2 (5.6) 0.9 (4.5) 0.56 (2.7) 0.47 (2.3) 0.24 (1.2)
10 Sinc3 1.5 (6.6) 1.1 (5.2) 0.89 (4.2) 0.54 (2.7) 0.46 (2.5) 0.24 (1.1)
10 Sinc4 1.5 (6.6) 0.99 (4.4) 0.79 (3.6) 0.49 (2.4) 0.39 (1.9) 0.2 (1)
16.6 Sinc1 2.6 (11) 1.7 (8.7) 1.4 (6.6) 0.87 (4.5) 0.72 (3.5) 0.37 (2)
16.6 Sinc2 2.1 (10) 1.5 (7.5) 1.1 (5.7) 0.78 (3.7) 0.62 (3.2) 0.32 (1.6)
16.6 Sinc3 1.9 (9.5) 1.4 (7.2) 1.1 (5.1) 0.72 (3.6) 0.54 (2.5) 0.27 (1.3)
16.6 Sinc4 1.8 (7.7) 1.3 (6.4) 0.97 (4.8) 0.65 (3.1) 0.48 (2.5) 0.24 (1.2)
20 FIR 3 (15) 2.1 (11) 1.8 (8.6) 1.1 (5.2) 0.89 (4.8) 0.46 (2.6)
20 Sinc1 2.7 (13) 1.9 (9.5) 1.5 (7.5) 0.97 (5.5) 0.76 (4.2) 0.43 (2.3)
20 Sinc2 2.2 (11) 1.5 (7.2) 1.3 (6) 0.83 (4.2) 0.69 (3.7) 0.35 (1.8)
20 Sinc3 2.1 (10) 1.6 (8.3) 1.2 (5.4) 0.77 (4) 0.64 (3.1) 0.31 (1.6)
20 Sinc4 2 (9.5) 1.3 (6.8) 1.1 (4.8) 0.65 (3.1) 0.56 (2.7) 0.28 (1.4)
50 Sinc1 4.1 (24) 2.9 (17) 2.3 (14) 1.5 (7.7) 1.2 (7.5) 0.64 (3.7)
50 Sinc2 3.2 (18) 2.3 (12) 1.9 (11) 1.3 (7) 1.1 (5.8) 0.54 (3.1)
50 Sinc3 3.3 (18) 2.2 (13) 1.8 (9.2) 1.2 (6.7) 0.93 (5.3) 0.49 (3)
50 Sinc4 3.1 (17) 2 (11) 1.6 (8.3) 1 (5.8) 0.87 (4.7) 0.43 (2.4)
60 Sinc1 4.5 (27) 3.1 (17) 2.4 (13) 1.6 (9.2) 1.4 (8.3) 0.69 (3.8)
60 Sinc2 3.8 (23) 2.6 (14) 2.1 (11) 1.4 (7.3) 1.2 (5.9) 0.57 (3.1)
60 Sinc3 3.4 (19) 2.3 (13) 1.8 (9.2) 1.3 (6.9) 1 (5.4) 0.54 (3.1)
60 Sinc4 3.3 (18) 2.1 (12) 1.9 (9.8) 1.2 (6.6) 0.95 (5.2) 0.52 (2.8)
100 Sinc1 5.6 (34) 4.1 (23) 3.3 (20) 2.1 (12) 1.8 (9.7) 0.91 (5.7)
100 Sinc2 4.9 (30) 3.4 (21) 2.7 (16) 1.8 (11) 1.5 (8.7) 0.75 (4.4)
100 Sinc3 4.4 (26) 3.1 (18) 2.5 (14) 1.7 (10) 1.3 (8.2) 0.69 (4.2)
100 Sinc4 4.1 (24) 2.9 (17) 2.3 (14) 1.5 (8.5) 1.3 (7.7) 0.63 (4)
400 Sinc1 12 (74) 8.1 (55) 6.4 (43) 4.3 (27) 3.6 (25) 1.8 (11)
400 Sinc2 9.3 (60) 6.7 (44) 5.3 (32) 3.5 (23) 2.9 (19) 1.5 (10)
400 Sinc3 8.6 (54) 6.2 (39) 4.9 (32) 3.2 (20) 2.7 (17) 1.4 (9.1)
400 Sinc4 8 (52) 5.6 (37) 4.5 (30) 3 (20) 2.5 (16) 1.3 (8.3)
1200 Sinc1 20 (140) 14 (98) 11 (75) 7.3 (48) 6 (40) 3.1 (20)
1200 Sinc2 17 (110) 12 (78) 9.2 (62) 6.1 (41) 5 (33) 2.6 (18)
1200 Sinc3 15 (100) 11 (72) 8.4 (56) 5.6 (37) 4.6 (31) 2.4 (16)
1200 Sinc4 14 (95) 9.9 (68) 7.8 (51) 5.2 (37) 4.3 (29) 2.2 (15)
2400 Sinc1 27 (200) 19 (140) 15 (110) 10 (72) 8.3 (60) 4.2 (30)
2400 Sinc2 23 (180) 16 (120) 13 (97) 8.7 (62) 7 (53) 3.6 (26)
2400 Sinc3 21 (160) 15 (110) 12 (94) 7.9 (59) 6.5 (50) 3.3 (23)
2400 Sinc4 20 (140) 14 (100) 11 (78) 7.3 (53) 6 (43) 3.1 (22)
4800 Sinc1 37 (270) 26 (200) 21 (160) 14 (110) 11 (83) 5.6 (42)
4800 Sinc2 33 (250) 23 (170) 18 (140) 12 (88) 9.8 (73) 5 (40)
4800 Sinc3 31 (230) 21 (150) 17 (130) 11 (83) 9 (65) 4.7 (36)
4800 Sinc4 29 (220) 20 (150) 16 (120) 11 (81) 8.5 (63) 4.4 (33)
7200 Sinc1 44 (330) 31 (230) 24 (180) 16 (120) 13 (98) 6.5 (48)
7200 Sinc2 39 (300) 28 (210) 22 (170) 14 (100) 12 (90) 5.9 (46)
7200 Sinc3 37 (280) 26 (200) 21 (160) 13 (100) 11 (82) 5.5 (41)
7200 Sinc4 35 (260) 25 (180) 20 (150) 13 (95) 10 (81) 5.3 (41)
14400 Sinc5 53 (430) 36 (290) 29 (220) 18 (140) 14 (120) 7.4 (58)
19200 Sinc5 72 (560) 50 (390) 39 (320) 23 (180) 17 (130) 8.8 (71)
25600 Sinc5 150 (1300) 100 (870) 79 (640) 42 (350) 26 (220) 13 (110)
40000 Sinc5 250 (2000) 160 (1300) 120 (1000) 65 (530) 37 (310) 19 (150)

Table 2. Typical Noise (en) in µVRMS and (µVPP), Gain = 4 to 128, VREF = 2.5 V

DATA RATE (SPS) FILTER MODE GAIN (Full-Scale Range)
4 (±625 mV) 8 (±312 mV) 16 (±156 mV) 32 (±78.1 mV) 64 (±39.1 mV) 128 (±19.5 mV)
2.5 FIR 0.082 (0.35) 0.051 (0.2) 0.032 (0.14) 0.027 (0.11) 0.027 (0.1) 0.029 (0.12)
2.5 Sinc1 0.088 (0.35) 0.05 (0.19) 0.024 (0.089) 0.024 (0.089) 0.023 (0.098) 0.024 (0.1)
2.5 Sinc2 0.059 (0.24) 0.037 (0.14) 0.021 (0.084) 0.018 (0.072) 0.017 (0.076) 0.019 (0.076)
2.5 Sinc3 0.06 (0.24) 0.034 (0.13) 0.019 (0.075) 0.017 (0.07) 0.016 (0.073) 0.018 (0.075)
2.5 Sinc4 0.054 (0.19) 0.034 (0.13) 0.019 (0.075) 0.016 (0.065) 0.015 (0.062) 0.016 (0.069)
5 FIR 0.12 (0.52) 0.071 (0.33) 0.046 (0.21) 0.038 (0.19) 0.039 (0.17) 0.037 (0.18)
5 Sinc1 0.11 (0.48) 0.061 (0.28) 0.038 (0.18) 0.029 (0.14) 0.029 (0.15) 0.029 (0.13)
5 Sinc2 0.093 (0.43) 0.048 (0.21) 0.029 (0.14) 0.024 (0.11) 0.026 (0.12) 0.023 (0.1)
5 Sinc3 0.081 (0.41) 0.044 (0.2) 0.03 (0.13) 0.023 (0.1) 0.022 (0.1) 0.022 (0.11)
5 Sinc4 0.066 (0.3) 0.043 (0.2) 0.027 (0.13) 0.022 (0.093) 0.022 (0.11) 0.021 (0.096)
10 FIR 0.19 (1) 0.099 (0.51) 0.064 (0.36) 0.053 (0.29) 0.051 (0.3) 0.054 (0.3)
10 Sinc1 0.16 (0.82) 0.086 (0.46) 0.054 (0.3) 0.045 (0.22) 0.043 (0.21) 0.044 (0.23)
10 Sinc2 0.12 (0.56) 0.068 (0.36) 0.044 (0.23) 0.037 (0.2) 0.034 (0.18) 0.033 (0.18)
10 Sinc3 0.11 (0.52) 0.066 (0.31) 0.042 (0.21) 0.032 (0.17) 0.032 (0.16) 0.032 (0.16)
10 Sinc4 0.096 (0.45) 0.059 (0.31) 0.039 (0.2) 0.032 (0.17) 0.031 (0.16) 0.03 (0.15)
16.6 Sinc1 0.19 (1) 0.11 (0.56) 0.075 (0.38) 0.054 (0.3) 0.055 (0.29) 0.056 (0.31)
16.6 Sinc2 0.16 (0.89) 0.086 (0.4) 0.054 (0.27) 0.044 (0.22) 0.049 (0.24) 0.046 (0.24)
16.6 Sinc3 0.15 (0.73) 0.084 (0.41) 0.053 (0.27) 0.041 (0.22) 0.04 (0.22) 0.041 (0.2)
16.6 Sinc4 0.13 (0.67) 0.076 (0.39) 0.053 (0.29) 0.042 (0.24) 0.04 (0.21) 0.036 (0.17)
20 FIR 0.24 (1.2) 0.14 (0.72) 0.088 (0.45) 0.072 (0.38) 0.071 (0.37) 0.074 (0.37)
20 Sinc1 0.22 (1.1) 0.12 (0.58) 0.079 (0.41) 0.064 (0.32) 0.061 (0.32) 0.06 (0.34)
20 Sinc2 0.18 (1) 0.1 (0.57) 0.062 (0.34) 0.049 (0.25) 0.049 (0.26) 0.047 (0.29)
20 Sinc3 0.16 (0.89) 0.089 (0.48) 0.063 (0.32) 0.046 (0.22) 0.045 (0.21) 0.045 (0.23)
20 Sinc4 0.15 (0.82) 0.083 (0.41) 0.056 (0.29) 0.045 (0.23) 0.042 (0.22) 0.046 (0.24)
50 Sinc1 0.35 (2.1) 0.19 (1.1) 0.12 (0.69) 0.097 (0.52) 0.096 (0.57) 0.098 (0.58)
50 Sinc2 0.28 (1.6) 0.15 (0.84) 0.099 (0.56) 0.075 (0.43) 0.077 (0.43) 0.076 (0.46)
50 Sinc3 0.25 (1.5) 0.14 (0.75) 0.093 (0.51) 0.074 (0.41) 0.07 (0.38) 0.071 (0.37)
50 Sinc4 0.23 (1.4) 0.13 (0.76) 0.087 (0.47) 0.066 (0.37) 0.065 (0.35) 0.065 (0.37)
60 Sinc1 0.38 (2.2) 0.21 (1.2) 0.14 (0.79) 0.11 (0.57) 0.1 (0.59) 0.1 (0.6)
60 Sinc2 0.3 (1.7) 0.17 (0.93) 0.11 (0.66) 0.085 (0.47) 0.084 (0.49) 0.083 (0.49)
60 Sinc3 0.27 (1.6) 0.15 (0.79) 0.097 (0.53) 0.078 (0.43) 0.078 (0.43) 0.076 (0.42)
60 Sinc4 0.27 (1.6) 0.14 (0.89) 0.092 (0.5) 0.075 (0.46) 0.076 (0.4) 0.073 (0.4)
100 Sinc1 0.49 (2.8) 0.27 (1.5) 0.17 (1) 0.14 (0.81) 0.14 (0.88) 0.13 (0.81)
100 Sinc2 0.39 (2.3) 0.22 (1.4) 0.14 (0.87) 0.11 (0.63) 0.11 (0.69) 0.11 (0.66)
100 Sinc3 0.35 (2.1) 0.2 (1.2) 0.13 (0.75) 0.1 (0.63) 0.1 (0.61) 0.1 (0.69)
100 Sinc4 0.32 (2) 0.18 (1.2) 0.13 (0.73) 0.094 (0.57) 0.092 (0.56) 0.093 (0.57)
400 Sinc1 0.94 (6) 0.53 (3.5) 0.34 (2.1) 0.27 (1.8) 0.27 (1.7) 0.27 (1.8)
400 Sinc2 0.78 (5.2) 0.44 (3.1) 0.29 (1.8) 0.22 (1.4) 0.22 (1.4) 0.22 (1.4)
400 Sinc3 0.72 (4.6) 0.4 (2.6) 0.26 (1.6) 0.2 (1.3) 0.2 (1.3) 0.2 (1.3)
400 Sinc4 0.67 (4.2) 0.37 (2.4) 0.24 (1.6) 0.19 (1.2) 0.19 (1.2) 0.19 (1.1)
1200 Sinc1 1.6 (12) 0.91 (6.3) 0.59 (4.1) 0.46 (3.1) 0.45 (3.1) 0.45 (3.1)
1200 Sinc2 1.3 (9.3) 0.76 (5.2) 0.49 (3.2) 0.39 (2.6) 0.38 (2.6) 0.38 (2.6)
1200 Sinc3 1.2 (8.2) 0.69 (4.7) 0.45 (3.1) 0.35 (2.4) 0.35 (2.4) 0.35 (2.2)
1200 Sinc4 1.2 (7.6) 0.64 (4.3) 0.41 (2.7) 0.33 (2.3) 0.32 (2.2) 0.32 (2.3)
2400 Sinc1 2.2 (17) 1.2 (8.9) 0.81 (5.8) 0.64 (4.5) 0.62 (4.5) 0.62 (4.6)
2400 Sinc2 1.9 (14) 1.1 (7.7) 0.68 (5) 0.54 (3.9) 0.54 (3.9) 0.54 (4)
2400 Sinc3 1.7 (14) 0.97 (7.1) 0.62 (4.4) 0.49 (3.5) 0.48 (3.4) 0.49 (3.5)
2400 Sinc4 1.6 (12) 0.91 (6.7) 0.59 (4.1) 0.46 (3.5) 0.46 (3.4) 0.46 (3.4)
4800 Sinc1 3 (23) 1.6 (13) 1.1 (7.8) 0.83 (6.2) 0.83 (6.2) 0.82 (6.1)
4800 Sinc2 2.6 (20) 1.5 (12) 0.95 (7.2) 0.75 (5.6) 0.74 (5.4) 0.73 (5.5)
4800 Sinc3 2.4 (19) 1.4 (10) 0.89 (6.4) 0.69 (5) 0.68 (5.2) 0.69 (5.5)
4800 Sinc4 2.3 (17) 1.3 (9.8) 0.82 (6.2) 0.64 (5) 0.65 (4.9) 0.64 (4.9)
7200 Sinc1 3.3 (25) 1.9 (15) 1.2 (9) 0.95 (7) 0.94 (6.9) 0.94 (7.1)
7200 Sinc2 3.1 (24) 1.7 (13) 1.1 (8.7) 0.87 (6.6) 0.86 (6.5) 0.86 (6.4)
7200 Sinc3 2.9 (22) 1.6 (12) 1.1 (7.9) 0.83 (6.1) 0.82 (6.2) 0.82 (6.4)
7200 Sinc4 2.8 (21) 1.6 (12) 1 (7.7) 0.79 (5.8) 0.78 (6) 0.78 (5.8)
14400 Sinc5 3.8 (29) 2.1 (17) 1.4 (11) 1.1 (8.4) 1.1 (8.1) 1 (8.4)
19200 Sinc5 4.6 (36) 2.5 (20) 1.6 (13) 1.2 (9.6) 1.2 (9.3) 1.2 (9.5)
25600 Sinc5 6.7 (56) 3.6 (29) 2.1 (17) 1.5 (13) 1.4 (12) 1.4 (12)
40000 Sinc5 9.6 (80) 5 (43) 2.9 (23) 2 (16) 1.8 (15) 1.8 (15)

ADC noise performance can also be expressed as effective resolution and noise-free resolution (bits). The resolution in bits are computed from the measured noise data. Effective resolution is computed from the RMS value of the measured noise data. Noise-free resolution is computed from the peak-to-peak value of the measured noise data, and is therefore the resolution with no code flicker. Equation 1 is used to compute effective resolution (bits) and noise-free resolution (bits) based on the noise values listed in Table 1 and Table 2.

Equation 1. Effective Resolution or Noise-Free Resolution (Bits) = 3.32 log(FSR / en)

where

  • FSR = Full-scale range = 2 VREF / Gain
  • en = Input-referred noise (RMS value for effective resolution, peak-to-peak value for noise-free resolution)

For example, with a full-scale range = ±13.3 V, data rate = 20 SPS, and filter mode = FIR, the RMS noise value (from Table 1) is 2.1 µV. The effective resolution is: 3.32 log (26.6 V / 2.1 µV) = 23.6 bits.

Figure 52 and Figure 53 show effective resolution (bits) using Equation 1. Figure 54 and Figure 55 show the noise-free resolution (bits) using Equation 1. The data are based on 2.5-V reference operation and the sinc3 filter mode. Effective resolution and noise-free resolution (bits) are improved by increasing the reference voltage (up to 5 V).

ADS125H02 D044_SBAS790.gif
VREF = 2.5 V, sinc3 filter mode
Figure 52. Effective Resolution, Gain = 0.125 to 2
ADS125H02 D046_SBAS790.gif
VREF = 2.5 V, sinc3 filter mode
Figure 54. Noise-Free Resolution, Gain = 0.125 to 2
ADS125H02 D045_SBAS790.gif
VREF = 2.5 V, sinc3 filter mode
Figure 53. Effective Resolution, Gain = 4 to 128
ADS125H02 D047_SBAS790.gif
VREF = 2.5 V, sinc3 filter mode
Figure 55. Noise-Free Resolution, Gain = 4 to 128