SLASEU7 March   2023 AFE781H1 , AFE881H1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1  Absolute Maximum Ratings
    2. 6.2  ESD Ratings
    3. 6.3  Recommended Operating Conditions
    4. 6.4  Thermal Information
    5. 6.5  Electrical Characteristics
    6. 6.6  Timing Requirements
    7. 6.7  Timing Diagrams
    8. 6.8  Typical Characteristics: VOUT DAC
    9. 6.9  Typical Characteristics: ADC
    10. 6.10 Typical Characteristics: Reference
    11. 6.11 Typical Characteristics: HART Modem
    12. 6.12 Typical Characteristics: Power Supply
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Digital-to-Analog Converter (DAC) Overview
        1. 7.3.1.1 DAC Resistor String
        2. 7.3.1.2 DAC Buffer Amplifier
        3. 7.3.1.3 DAC Transfer Function
        4. 7.3.1.4 DAC Gain and Offset Calibration
        5. 7.3.1.5 Programmable Slew Rate
        6. 7.3.1.6 DAC Register Structure and CLEAR State
      2. 7.3.2 Analog-to-Digital Converter (ADC) Overview
        1. 7.3.2.1 ADC Operation
        2. 7.3.2.2 ADC Custom Channel Sequencer
        3. 7.3.2.3 ADC Synchronization
        4. 7.3.2.4 ADC Offset Calibration
        5. 7.3.2.5 External Monitoring Inputs
        6. 7.3.2.6 Temperature Sensor
        7. 7.3.2.7 Self-Diagnostic Multiplexer
        8. 7.3.2.8 ADC Bypass
      3. 7.3.3 Programmable Out-of-Range Alarms
        1. 7.3.3.1 Alarm-Based Interrupts
        2. 7.3.3.2 Alarm Action Configuration Register
        3. 7.3.3.3 Alarm Voltage Generator
        4. 7.3.3.4 Temperature Sensor Alarm Function
        5. 7.3.3.5 Internal Reference Alarm Function
        6. 7.3.3.6 ADC Alarm Function
        7. 7.3.3.7 Fault Detection
      4. 7.3.4 IRQ
      5. 7.3.5 HART Interface
        1. 7.3.5.1  FIFO Buffers
          1. 7.3.5.1.1 FIFO Buffer Access
          2. 7.3.5.1.2 FIFO Buffer Flags
        2. 7.3.5.2  HART Modulator
        3. 7.3.5.3  HART Demodulator
        4. 7.3.5.4  HART Modem Modes
          1. 7.3.5.4.1 Half-Duplex Mode
          2. 7.3.5.4.2 Full-Duplex Mode
        5. 7.3.5.5  HART Modulation and Demodulation Arbitration
          1. 7.3.5.5.1 HART Receive Mode
          2. 7.3.5.5.2 HART Transmit Mode
        6. 7.3.5.6  HART Modulator Timing and Preamble Requirements
        7. 7.3.5.7  HART Demodulator Timing and Preamble Requirements
        8. 7.3.5.8  IRQ Configuration for HART Communication
        9. 7.3.5.9  HART Communication Using the SPI
        10. 7.3.5.10 HART Communication Using UART
        11. 7.3.5.11 Memory Built-In Self-Test (MBIST)
      6. 7.3.6 Internal Reference
      7. 7.3.7 Integrated Precision Oscillator
      8. 7.3.8 One-Time Programmable (OTP) Memory
    4. 7.4 Device Functional Modes
      1. 7.4.1 DAC Power-Down Mode
      2. 7.4.2 Reset
    5. 7.5 Programming
      1. 7.5.1 Communication Setup
        1. 7.5.1.1 SPI Mode
        2. 7.5.1.2 UART Mode
        3. 7.5.1.3 SPI Plus UART Mode
        4. 7.5.1.4 HART Functionality Setup Options
      2. 7.5.2 Serial Peripheral Interface (SPI)
        1. 7.5.2.1 SPI Frame Definition
        2. 7.5.2.2 SPI Read and Write
        3. 7.5.2.3 Frame Error Checking
        4. 7.5.2.4 Synchronization
      3. 7.5.3 UART Interface
        1. 7.5.3.1 UART Break Mode (UBM)
          1. 7.5.3.1.1 Interface With FIFO Buffers and Register Map
      4. 7.5.4 Status Bits
      5. 7.5.5 Watchdog Timer
    6. 7.6 Register Maps
      1. 7.6.1 AFEx81H1 Registers
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Multichannel Configuration
    2. 8.2 Typical Application
      1. 8.2.1 4-mA to 20-mA Current Transmitter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Start-Up Circuit
          2. 8.2.1.2.2 Current Loop Control
          3. 8.2.1.2.3 Input Protection and Rectification
          4. 8.2.1.2.4 System Current Budget
        3. 8.2.1.3 Application Curves
    3. 8.3 Initialization Set Up
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  10. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.5.7 HART Demodulator Timing and Preamble Requirements

The RX_IN and RX_INF pins are continuously monitored by the HART demodulator when not transmitting. AFEx81H1 requires at least 3 mark bits (3 × tBAUDHART) of 1200 Hz for carrier detection.

For UART-based communication setup, the HART data are automatically dequeued from FIFO_H2U and transmitted on the UARTOUT pin as UART characters. A delay of approximately 1.5 bit times (1.5 × tBAUDHART) occurs as a result of data decoding and synchronization from the end of the character on RX_IN or RX_INF pin until the data are enqueued into FIFO_H2U. Thus, when CD deasserts, there is typically still one UART character pending transfer to the system controller on UARTOUT (see Figure 7-24).

FIFO latency is as low as a few microseconds when using the SPI to dequeue the data from FIFO_H2U by reading FIFO_H2U_RD register. Figure 7-23 and Figure 7-24 show the timing diagrams for the start and end of the HART receive character, respectively.

Figure 7-23 HART Receive Start Timing Diagram (SPI and UART Modes)
Figure 7-24 HART Receive End Timing Diagram (UART Mode)