SLASF43 December   2023 AFE782H1 , AFE882H1

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  Precision Oscillator Diagnostics
      9. 6.3.9  One-Time Programmable (OTP) Memory
      10. 6.3.10 GPIO
      11. 6.3.11 Timer
      12. 6.3.12 Unique Chip Identifier (ID)
      13. 6.3.13 Scratch Pad Register
    4. 6.4 Device Functional Modes
      1. 6.4.1 DAC Power-Down Mode
      2. 6.4.2 Register Built-In Self-Test (RBIST)
      3. 6.4.3 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 GPIO Programming
      3. 6.5.3 Serial Peripheral Interface (SPI)
        1. 6.5.3.1 SPI Frame Definition
        2. 6.5.3.2 SPI Read and Write
        3. 6.5.3.3 Frame Error Checking
        4. 6.5.3.4 Synchronization
      4. 6.5.4 UART Interface
        1. 6.5.4.1 UART Break Mode (UBM)
          1. 6.5.4.1.1 Interface With FIFO Buffers and Register Map
      5. 6.5.5 Status Bits
      6. 6.5.6 Watchdog Timer
  8. 7 Register Maps
    1. 7.1 AFEx82H1 Registers
  9. 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 Current Loop Control
          2. 8.2.1.2.2 HART Connections
          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 Setup
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  10. 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
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RRU|24
Thermal pad, mechanical data (Package|Pins)
Orderable Information

6.3.5.6 HART Modulator Timing and Preamble Requirements

The HART modulator starts modulating the carrier as soon as the CTS response is asserted. If data are enqueued into FIFO_U2H before the CTS is asserted, make sure to enqueue the required preamble bytes at the beginning of the data packet in accordance with Table 6-7. The first byte is used by the HART recipient receiver to recognize the carrier and properly detect the mark-to-space transition of the start bit in the second character. Alternatively, wait for CTS_ASSERT, and give an appropriate delay while the modulator is transmitting the mark signal. Then enqueue the preamble bytes followed by the data bytes into FIFO_U2H. Monitor the level of FIFO_U2H and timely enqueue the new data to avoid transmission gap errors.

Table 6-6 Carrier Detect and Preamble
HART REQUIREMENT FIFO_U2H STATE AFEx82H1 BEHAVIOR RECOMMENDED USE CASE
Transmit at least 6 bit times of HART signal of specified amplitude for the carrier to be detected by the receiver. FIFO_U2H is empty. HART modulator starts sending mark FSK signal as soon as CTS is asserted. Wait at least 6 bit times from CTS assert before transmitting first preamble byte. Calculate the time to enqueue the data into FIFO_U2H based on the interface mode used.
FIFO_U2H is preloaded with data. HART modulator starts sending FIFO_U2H data as soon as CTS is asserted. Preload FIFO_U2H with one additional preamble byte.

Depending on the interface mode, there is a latency from the UARTIN or CS pin to the MOD_OUT pin as a result of using FIFO_U2H in the data path.

In the SPI plus UART and UBM modes, a delay of approximately 1.5 bit times (1.5 × tBAUDUART) occurs from the stop bit on the UARTIN pin until the data are enqueued into FIFO_U2H as a result of data decoding and synchronization. Figure 6-23 shows this timing.

GUID-20210629-CA0I-K4V2-8X9T-FJHH2XDG9CMZ-low.svg Figure 6-20 HART Transmit Start Timing Diagram (UART Mode)

In SPI only mode, the HART transmit data are enqueued into FIFO_U2H using FIFO_U2H_WR register. Therefore, in this mode, take the standard SPI timing into consideration while calculating the latency of the HART transmit data from the CS pin to the MOD_OUT pin. Figure 6-21 shows the HART transmit start timing for SPI mode.

GUID-20230211-SS0I-RPQX-KC7W-TH0XCPGTR1SB-low.svg Figure 6-21 HART Transmit Start Timing Diagram (SPI Mode)

The HART character contains 11 bits; therefore, a delay of approximately 11 bit times (11 × tBAUDHART) occurs from the moment the data are dequeued from FIFO_U2H until the data are fully transmitted on the MOD_OUT pin (see Figure 6-24).

Additional delay is accumulated when there is a frequency mismatch between the incoming UART_IN data and the HART data transmitted on MOD_OUT. If the UART_IN data frequency is 2% greater compared to the MOD_OUT data frequency, a delay of approximately 1 bit time is accumulated every five HART characters. Add a gap of at least 1 bit time between every five HART characters to account for this latency. Keep the request to send (RTS) asserted until the data are fully transmitted on MOD_OUT.

GUID-20210629-CA0I-CZQQ-0BJH-7JMMG0XPGDKB-low.svg Figure 6-22 HART Transmit End Timing Diagram (UBM, UART Plus SPI Modes)