SLASEU7A March   2023  – October 2026 AFE781H1 , AFE881H1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Electrical Characteristics
    6. 5.6  Timing Requirements
    7. 5.7  Timing Diagrams
    8. 5.8  Typical Characteristics: VOUT DAC
    9. 5.9  Typical Characteristics: ADC
    10. 5.10 Typical Characteristics: Reference
    11. 5.11 Typical Characteristics: HART Modem
    12. 5.12 Typical Characteristics: Power Supply
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Digital-to-Analog Converter (DAC) Overview
        1. 6.3.1.1 DAC Resistor String
        2. 6.3.1.2 DAC Buffer Amplifier
        3. 6.3.1.3 DAC Transfer Function
        4. 6.3.1.4 DAC Gain and Offset Calibration
        5. 6.3.1.5 Programmable Slew Rate
        6. 6.3.1.6 DAC Register Structure and CLEAR State
      2. 6.3.2 Analog-to-Digital Converter (ADC) Overview
        1. 6.3.2.1 ADC Operation
        2. 6.3.2.2 ADC Custom Channel Sequencer
        3. 6.3.2.3 ADC Synchronization
        4. 6.3.2.4 ADC Offset Calibration
        5. 6.3.2.5 External Monitoring Inputs
        6. 6.3.2.6 Temperature Sensor
        7. 6.3.2.7 Self-Diagnostic Multiplexer
        8. 6.3.2.8 ADC Bypass
      3. 6.3.3 Programmable Out-of-Range Alarms
        1. 6.3.3.1 Alarm-Based Interrupts
        2. 6.3.3.2 Alarm Action Configuration Register
        3. 6.3.3.3 Alarm Voltage Generator
        4. 6.3.3.4 Temperature Sensor Alarm Function
        5. 6.3.3.5 Internal Reference Alarm Function
        6. 6.3.3.6 ADC Alarm Function
        7. 6.3.3.7 Fault Detection
      4. 6.3.4 IRQ
      5. 6.3.5 HART Interface
        1. 6.3.5.1  FIFO Buffers
          1. 6.3.5.1.1 FIFO Buffer Access
          2. 6.3.5.1.2 FIFO Buffer Flags
        2. 6.3.5.2  HART Modulator
        3. 6.3.5.3  HART Demodulator
        4. 6.3.5.4  HART Modem Modes
          1. 6.3.5.4.1 Half-Duplex Mode
          2. 6.3.5.4.2 Full-Duplex Mode
        5. 6.3.5.5  HART Modulation and Demodulation Arbitration
          1. 6.3.5.5.1 HART Receive Mode
          2. 6.3.5.5.2 HART Transmit Mode
        6. 6.3.5.6  HART Modulator Timing and Preamble Requirements
        7. 6.3.5.7  HART Demodulator Timing and Preamble Requirements
        8. 6.3.5.8  IRQ Configuration for HART Communication
        9. 6.3.5.9  HART Communication Using the SPI
        10. 6.3.5.10 HART Communication Using UART
        11. 6.3.5.11 Memory Built-In Self-Test (MBIST)
      6. 6.3.6 Internal Reference
      7. 6.3.7 Integrated Precision Oscillator
      8. 6.3.8 One-Time Programmable (OTP) Memory
    4. 6.4 Device Functional Modes
      1. 6.4.1 DAC Power-Down Mode
      2. 6.4.2 Reset
    5. 6.5 Programming
      1. 6.5.1 Communication Setup
        1. 6.5.1.1 SPI Mode
        2. 6.5.1.2 UART Mode
        3. 6.5.1.3 SPI Plus UART Mode
        4. 6.5.1.4 HART Functionality Setup Options
      2. 6.5.2 Serial Peripheral Interface (SPI)
        1. 6.5.2.1 SPI Frame Definition
        2. 6.5.2.2 SPI Read and Write
        3. 6.5.2.3 Frame Error Checking
        4. 6.5.2.4 Synchronization
      3. 6.5.3 UART Interface
        1. 6.5.3.1 UART Break Mode (UBM)
          1. 6.5.3.1.1 Interface With FIFO Buffers and Register Map
      4. 6.5.4 Status Bits
      5. 6.5.5 Watchdog Timer
    6. 6.6 Register Maps
      1. 6.6.1 AFEx81H1 Registers
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Multichannel Configuration
    2. 7.2 Typical Application
      1. 7.2.1 4mA to 20mA Current Transmitter
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Start-Up Circuit
          2. 7.2.1.2.2 Current Loop Control
          3. 7.2.1.2.3 Input Protection and Rectification
          4. 7.2.1.2.4 System Current Budget
        3. 7.2.1.3 Application Curves
    3. 7.3 Initialization Set Up
    4. 7.4 Power Supply Recommendations
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
      2. 7.5.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.1 Digital-to-Analog Converter (DAC) Overview

The AFEx81H1 feature a 16‑bit (AFE881H1) or 14-bit (AFE781H1) string DAC followed by an output voltage buffer. The DAC can be configured to support two low PVDD (0.15V to 1.25V and 0.2V to 1V), or high PVDD (0.3V to 2.5V and 0.4V to 2V) output ranges of operation depending on the PVDD supply voltage and the DAC_CFG.RANGE bit in the device configuration register. Using a voltage-to-current converter stage, these output voltages can be used to control a 4mA to 20mA loop. The narrow range corresponds to a 4mA to 20mA range. The full range allows for currents under and over the 4mA to 20mA range.

The devices continuously monitor the PVDD supply to provide proper operation based on the DAC range setting. Table 6-1 shows the valid supply ranges and corresponding VOUT DAC voltage ranges for the AFEx81H1.

Table 6-1 VOUT DAC Voltage Ranges
DAC CONFIGURATION SUPPLY DAC_CFG.RANGE NAME VOUT DAC VOLTAGE RANGE
PVDD VDD
Invalid configuration 0V ≤ PVDD < 1.71V 0V ≤ VDD < 1.71V NA Alarm condition1 0.15V or 1.25V2
Low PVDD DAC range 1.71V ≤ PVDD ≤ 1.89V 1.71V ≤ VDD ≤ 1.89V 0 Full range 0.15V to 1.25V
1 Narrow range 0.2V to 1V
Invalid configuration 1.89V < PVDD < 2.7V VDD > 1.89V NA Alarm condition1 0.15V or 1.25V2
High PVDD DAC range 2.7V ≤ PVDD ≤ 5.5V VDD is internally generated 0 Full range 0.3V to 2.5V
1 Narrow range 0.4V to 2V
Invalid configuration PVDD > 5.5V VDD > 1.89V NA Alarm condition1 0.3V or 2.5V2
(1) See Table 6-9 for details.
(2) See Figure 6-12 for details.

If PVDD or VDD fall outside the specified threshold values associated with the supply configuration during operation, an alarm triggers and the DAC output sets according to the ALARM_ACT register settings.