SLASF44 may   2023 AFE78201 , AFE88201

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-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  Internal Reference
      6. 7.3.6  Integrated Precision Oscillator
      7. 7.3.7  Precision Oscillator Diagnostics
      8. 7.3.8  One-Time Programmable (OTP) Memory
      9. 7.3.9  GPIO
      10. 7.3.10 Timer
      11. 7.3.11 Unique Chip Identifier (ID)
      12. 7.3.12 Scratch Pad Register
    4. 7.4 Device Functional Modes
      1. 7.4.1 Register Built-In Self-Test (RBIST)
      2. 7.4.2 DAC Power-Down Mode
      3. 7.4.3 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 GPIO Programming
      3. 7.5.3 Serial Peripheral Interface (SPI)
        1. 7.5.3.1 SPI Frame Definition
        2. 7.5.3.2 SPI Read and Write
        3. 7.5.3.3 Frame Error Checking
        4. 7.5.3.4 Synchronization
      4. 7.5.4 UART Interface
        1. 7.5.4.1 UART Break Mode (UBM)
      5. 7.5.5 Status Bits
      6. 7.5.6 Watchdog Timer
    6. 7.6 Register Maps
      1. 7.6.1 AFEx8201 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 Analog Output Module
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 XTR305
            1. 8.2.1.2.1.1 Current-Output Mode
            2. 8.2.1.2.1.2 Voltage Output Mode
            3. 8.2.1.2.1.3 Diagnostic Features
        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
  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

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報
8.2.1.2.1.1 Current-Output Mode

In the current-output mode, a 0-V to 2.5-V control input is converted to a ±25-mA current output. As the input is unipolar, and the output is bipolar, a reference bias voltage (VREF) is required on the input stage of the XTR305. The bias voltage of 1.25 V is taken from a buffered VREFIO output from the AFE88201. Figure 8-4 shows the configuration of the XTR305 in current-output mode.

GUID-20221106-SS0I-1973-PSMT-G5FTJGRFBXGV-low.svg Figure 8-4 The XTR305 Standard Circuit for Current Output

For current-output mode, OD is set high, M1 is set low, and M2 is set high. The normal transfer function for this circuit is given in Equation 10.

Equation 10. I O U T =   10 × V I N R S E T   +   V I N   –   V R E F R O S

However, with the RSET resistor as an open circuit, the singular VIN term drops out. Using Equation 10, the ROS term sets the output. The transconductance gain is set by ROS according to Equation 11.

Equation 11. R O S =   10 I o u t F S R × V i n F S R = 10 50   m A × 2.5   V = 500   Ω

Select ROS = 499 Ω as a standard resistor value. This gives an IoutFSR of 50.1 mA, with an output range of ±25.05 mA. The transfer function is given by Equation 12.

Equation 12. I O U T =   10 R O S × V i n –   V R E F    

Using the AFE88201, the transfer function from code to output current is shown in Equation 13.

Equation 13. I O U T = 10 R O S × D A C _ C O D E   ×   2.5   V 2 16   – 1.25 V

When using the current-output mode, the output load voltage can be monitored through an analog output monitor in the XTR305. See also Section 8.2.1.2.1.3.