SBAS444D May   2009  – January 2018 ADS1113 , ADS1114 , ADS1115

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Block Diagrams
  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: I2C
    7. 7.7 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 Diagrams
    3. 9.3 Feature Description
      1. 9.3.1 Multiplexer
      2. 9.3.2 Analog Inputs
      3. 9.3.3 Full-Scale Range (FSR) and LSB Size
      4. 9.3.4 Voltage Reference
      5. 9.3.5 Oscillator
      6. 9.3.6 Output Data Rate and Conversion Time
      7. 9.3.7 Digital Comparator (ADS1114 and ADS1115 Only)
      8. 9.3.8 Conversion Ready Pin (ADS1114 and ADS1115 Only)
      9. 9.3.9 SMbus Alert Response
    4. 9.4 Device Functional Modes
      1. 9.4.1 Reset and Power-Up
      2. 9.4.2 Operating Modes
        1. 9.4.2.1 Single-Shot Mode
        2. 9.4.2.2 Continuous-Conversion Mode
      3. 9.4.3 Duty Cycling For Low Power
    5. 9.5 Programming
      1. 9.5.1 I2C Interface
        1. 9.5.1.1 I2C Address Selection
        2. 9.5.1.2 I2C General Call
        3. 9.5.1.3 I2C Speed Modes
      2. 9.5.2 Slave Mode Operations
        1. 9.5.2.1 Receive Mode
        2. 9.5.2.2 Transmit Mode
      3. 9.5.3 Writing To and Reading From the Registers
      4. 9.5.4 Data Format
    6. 9.6 Register Map
      1. 9.6.1 Address Pointer Register (address = N/A) [reset = N/A]
        1. Table 6. Address Pointer Register Field Descriptions
      2. 9.6.2 Conversion Register (P[1:0] = 0h) [reset = 0000h]
        1. Table 7. Conversion Register Field Descriptions
      3. 9.6.3 Config Register (P[1:0] = 1h) [reset = 8583h]
        1. Table 8. Config Register Field Descriptions
      4. 9.6.4 Lo_thresh (P[1:0] = 2h) [reset = 8000h] and Hi_thresh (P[1:0] = 3h) [reset = 7FFFh] Registers
        1. Table 9. Lo_thresh and Hi_thresh Register Field Descriptions
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Basic Connections
      2. 10.1.2 Single-Ended Inputs
      3. 10.1.3 Input Protection
      4. 10.1.4 Unused Inputs and Outputs
      5. 10.1.5 Analog Input Filtering
      6. 10.1.6 Connecting Multiple Devices
      7. 10.1.7 Quickstart Guide
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Shunt Resistor Considerations
        2. 10.2.2.2 Operational Amplifier Considerations
        3. 10.2.2.3 ADC Input Common-Mode Considerations
        4. 10.2.2.4 Resistor (R1, R2, R3, R4) Considerations
        5. 10.2.2.5 Noise and Input Impedance Considerations
        6. 10.2.2.6 First-order RC Filter Considerations
        7. 10.2.2.7 Circuit Implementation
        8. 10.2.2.8 Results Summary
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
    1. 11.1 Power-Supply Sequencing
    2. 11.2 Power-Supply Decoupling
  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 Related Links
    3. 13.3 Receiving Notification of Documentation Updates
    4. 13.4 Community Resources
    5. 13.5 Trademarks
    6. 13.6 Electrostatic Discharge Caution
    7. 13.7 Glossary
  14. 14Mechanical, Packaging, and Orderable Information

10.2.2.6 First-order RC Filter Considerations

Although the device digital filter attenuates high-frequency noise, use a first order low-pass RC filter at the ADC inputs to further reject out-of-bandwidth noise and avoid aliasing. A differential low-pass RC filter formed by R5, R6, and the differential capacitor CDIFF sets the –3-dB cutoff frequency, fC, given by Equation 16. These filter resistors produce a voltage drop because of the input currents flowing into and out of the ADC. This voltage drop could contribute to an additional gain error. Limit the filter resistor values to below 1 kΩ.

Equation 16. fC = 1 / [2π · (R5 + R6) · CDIFF]

Two common-mode filter capacitors (CCM1 and CCM2) are also added to offer attenuation of high-frequency, common-mode noise components. Select a differential capacitor, CDIFF, that is at least an order of magnitude (10x) larger than these common-mode capacitors because mismatches in these common-mode capacitors can convert common-mode noise into differential noise.