SLASF21 December   2022 AFE78101 , AFE88101

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: 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 Action Configuration Register
        2. 7.3.3.2 Alarm Voltage Generator
        3. 7.3.3.3 Temperature Sensor Alarm Function
        4. 7.3.3.4 Internal Reference Alarm Function
        5. 7.3.3.5 ADC Alarm Function
        6. 7.3.3.6 Fault Detection
      4. 7.3.4 IRQ
      5. 7.3.5 Internal Reference
      6. 7.3.6 Integrated Precision Oscillator
      7. 7.3.7 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
      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
        1. 7.5.3.1 UART Break Mode (UBM)
      4. 7.5.4 Status Bits
      5. 7.5.5 Watchdog Timer
    6. 7.6 Register Maps
      1. 7.6.1 AFEx8101 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

7.3.1.6 DAC Register Structure and CLEAR State

The AFE88101 DAC has a 16-bit voltage output, and the AFE78101 DAC has a 14-bit voltage output. Table 7-1 shows four possible VOUT DAC output ranges. With a voltage-to-current converter stage, the narrow range corresponds to a 4-mA to 20-mA range. The full range allows for undercurrents and overcurrents from 3 mA to 25 mA, and is controlled by DAC_CFG.RANGE.

The AFEx8101 provide the option to quickly set the DAC output to the value set in the DAC_CLR_CODE register without writing to the DAC_DATA register, referred to as the CLEAR state. Setting the DAC to CLEAR state also sets the DAC output range according to DAC_CFG.CLR_RANGE. For register details, see Table 7-15.

Transitioning from the DAC_DATA to the DAC_CLR_CODE is synchronous to the clock. If slew mode is enabled, the output slews during the transition. Figure 7-7 shows the full AFEx8101 DAC_DATA signal path. The devices synchronize the DAC_DATA code to the internal clock, causing up to 2.5 internal clock cycles of latency (2 μs) with respect to the rising edge of CS or the end of a UBM command. Update DAC_GAIN and DAC_OFFSET values when DAC_CFG.SR_EN = 0 to avoid an IRQ pulse generated by SR_BUSY.

Set the DAC to CLEAR state either by:

  1. Setting DAC_CFG.CLR.
  2. Configuring the DAC to transition to the CLEAR state in response to an alarm condition.
  3. Using the SDI pin in UBM or the SCLR pin in SPI mode as the CLEAR state input pin.

Method 1 is a direct command to the AFEx8101 to set the DAC to CLEAR state. Set the DAC_CFG.CLR bit to 1h to set the DAC to CLEAR state.

Method 2 is controlled by settings of ALARM_ACT register. For details of conditions and other masks required to use this method, see Table 7-24 and Section 7.3.3.1.

Method 3 supports setting the DAC to CLEAR state without writing to the AFEx8101. This pin-based DAC CLEAR state function is available in SPI mode on the SCLR pin, or in UBM on the SDI pin. The SCLR pin must be tied to GND in UBM. For details of connection options based on communication modes and pins used in each mode, see Section 7.5.1. Set the appropriate pin high to drive the DAC to CLEAR state.

Figure 7-7 DAC Data Path