SBAS999A June   2019  – January 2021 ADS125H01

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and 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 Timing Diagrams
    9. 7.9 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 Voltage Range
      2. 9.3.2 Analog Inputs (AINP, AINN)
        1. 9.3.2.1 ESD Diodes
        2. 9.3.2.2 Input Switch
      3. 9.3.3 Programmable Gain Amplifier (PGA)
        1. 9.3.3.1 PGA Operating Range
        2. 9.3.3.2 PGA Monitors
      4. 9.3.4 Reference Voltage
        1. 9.3.4.1 Reference Monitor
      5. 9.3.5 ADC Modulator
      6. 9.3.6 Digital Filter
        1. 9.3.6.1 Sinc Filter Mode
          1. 9.3.6.1.1 Sinc Filter Frequency Response
        2. 9.3.6.2 FIR Filter
        3. 9.3.6.3 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 Clock Mode
      3. 9.4.3 Reset
        1. 9.4.3.1 Power-On Reset
        2. 9.4.3.2 Reset by RESETPin
        3. 9.4.3.3 Reset by Command
      4. 9.4.4 Calibration
        1. 9.4.4.1 Offset and Full-Scale Calibration
          1. 9.4.4.1.1 Offset Calibration Registers
          2. 9.4.4.1.2 Full-Scale Calibration Registers
        2. 9.4.4.2 Offset Calibration Command (OFSCAL)
        3. 9.4.4.3 Full-Scale Calibration Command (GANCAL)
        4. 9.4.4.4 Calibration Command Procedure
        5. 9.4.4.5 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
    6. 9.6 Register Map
      1. 9.6.1  Device Identification (ID) Register (address = 00h) [reset = 4xh]
      2. 9.6.2  Main Status (STATUS0) Register (address = 01h) [reset = 01h]
      3. 9.6.3  Mode 0 (MODE0) Register (address = 02h) [reset = 24h]
      4. 9.6.4  Mode 1 (MODE1) Register (address = 03h) [reset = 01h]
      5. 9.6.5  Reserved (RESERVED) Register (address = 04h) [reset = 00h]
      6. 9.6.6  Mode 3 (MODE3) Register (address = 05h) [reset = 00h]
      7. 9.6.7  Reference Configuration (REF) Register (address = 06h) [reset = 05h]
      8. 9.6.8  Offset Calibration (OFCALx) Registers (address = 07h, 08h, 09h) [reset = 00h, 00h, 00h]
      9. 9.6.9  Full-Scale Calibration (FSCALx) Registers (address = 0Ah, 0Bh, 0Ch) [reset = 00h, 00h, 40h]
      10. 9.6.10 Reserved (RESERVED) Register (address = 0Dh) [reset = FFh]
      11. 9.6.11 Reserved (RESERVED) Register (address = 0Eh) [reset = 00h]
      12. 9.6.12 Reserved (RESERVED) Register (address = 0Fh) [reset = 00h]
      13. 9.6.13 MODE4 (MODE4) Register (address = 10h) [reset = 50h]
      14. 9.6.14 PGA Alarm (STATUS1) Register (address = 11h) [reset = xxh]
      15. 9.6.15 Status 2 (STATUS2) Register (address = 12h) [reset = 0xh]
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Example to Determine the PGA Linear Operating Range
      2. 10.1.2 Input Signal Rate of Change (dV/dt)
      3. 10.1.3 Unused Inputs and Outputs
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
      3. 10.2.3 Application Curve
  11. 11Power Supply Recommendations
    1. 11.1 Power-Supply Decoupling
    2. 11.2 Analog Power-Supply Clamp
    3. 11.3 Power-Supply Sequencing
  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 Support 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

9.3.3.1 PGA Operating Range

The absolute input voltage range of the PGA must not be exceeded in order to maintain linear operation. The maximum and minimum absolute input voltage is determined by the PGA gain setting, the maximum differential input voltage (VIN), and the minimum value of the high-voltage power supply. The absolute voltage is the combined differential and common-mode voltages. Maintain the absolute input voltage (VAINx) within the range as shown in Equation 3, otherwise incorrect conversion data can result.

Equation 3. HV_AVSS + 2.5 V + VIN × (Gain – 1) / 2 < V(AINx) < HV_AVDD – 2.5 V – VIN × (Gain – 1) / 2

where:

  • Gain = PGA gain. For gain < 1, use value = 1
  • V(AINx) = Absolute input voltage
  • VIN = VAINP – VAINN = Maximum expected differential input voltage

Additionally, the differential input signal is limited in two conditions. The first condition is when the reference voltage exceeds AVDD – 1 V (nominally VREF > 4 V). In this case, the differential input signal is limited to: VIN = ±(AVDD – 1 V) / Gain, instead of the ideal VIN = ±VREF / Gain. The second condition applies to gains of 0.125 and 0.1875. In this case, the differential input signal range is limited to: VIN = ±20 V, regardless of the reference voltage value.

Figure 9-2 and Figure 9-3 show the relationship between the PGA input voltage and the PGA output voltage. In attenuation mode, the first PGA stage is configured as a unity-gain follower. The second PGA stage attenuates the differential input voltage and shifts the signal common-mode voltage to AVDD / 2 to drive the ADC input.

In gain mode, the first PGA stage amplifies the differential signal. The second PGA stage is configured as a unity-gain follower with level-shift. Figure 9-2 and Figure 9-3 show the corresponding output voltage of the PGA stages that must have operating voltage headroom.

GUID-0F4EBB82-A2EA-49E8-A56B-7BCE0E1039E5-low.gif Figure 9-2 PGA Attenuation Mode
GUID-BE98F6EF-E012-4170-9AA8-E036D9A6A7A5-low.gif Figure 9-3 PGA Gain Mode