SBASA57 September   2023 AMC131M01

PRODUCTION DATA  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Revision History
  6. Pin Configuration and Functions
  7. 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  Insulation Specifications
    6. 6.6  Safety-Related Certifications
    7. 6.7  Safety Limiting Values
    8. 6.8  Electrical Characteristics
    9. 6.9  Timing Requirements
    10. 6.10 Switching Characteristics
    11. 6.11 Timing Diagrams
    12. 6.12 Typical Characteristics
  8. Parameter Measurement Information
    1. 7.1 Noise Measurements
  9. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Isolated DC/DC Converter
        1. 8.3.1.1 DC/DC Converter Failure Detection
      2. 8.3.2  High-Side Current Drive Capability
      3. 8.3.3  Isolation Channel Signal Transmission
      4. 8.3.4  Input ESD Protection Circuitry
      5. 8.3.5  Input Multiplexer
      6. 8.3.6  Programmable Gain Amplifier (PGA)
      7. 8.3.7  Voltage Reference
      8. 8.3.8  Internal Test Signals
      9. 8.3.9  Clocking and Power Modes
      10. 8.3.10 ΔΣ Modulator
      11. 8.3.11 Digital Filter
        1. 8.3.11.1 Digital Filter Implementation
          1. 8.3.11.1.1 Fast-Settling Filter
          2. 8.3.11.1.2 SINC3 and SINC3 + SINC1 Filter
        2. 8.3.11.2 Digital Filter Characteristic
      12. 8.3.12 Calibration Registers
      13. 8.3.13 Register Map CRC
      14. 8.3.14 General-Purpose Digital Output (GPO)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-Up and Reset
        1. 8.4.1.1 Power-On Reset
        2. 8.4.1.2 SYNC/RESET Pin
        3. 8.4.1.3 RESET Command
      2. 8.4.2 Start-Up Behavior After Power-Up
      3. 8.4.3 Start-Up Behavior After a Pin Reset or RESET Command
      4. 8.4.4 Start-Up Behavior After a Pause in CLKIN
      5. 8.4.5 Synchronization
      6. 8.4.6 Conversion Modes
        1. 8.4.6.1 Continuous-Conversion Mode
        2. 8.4.6.2 Global-Chop Mode
      7. 8.4.7 Power Modes
      8. 8.4.8 Standby Mode
    5. 8.5 Programming
      1. 8.5.1 Serial Interface
        1. 8.5.1.1  Chip Select (CS)
        2. 8.5.1.2  Serial Data Clock (SCLK)
        3. 8.5.1.3  Serial Data Input (DIN)
        4. 8.5.1.4  Serial Data Output (DOUT)
        5. 8.5.1.5  Data Ready (DRDY)
        6. 8.5.1.6  Conversion Synchronization or System Reset (SYNC/RESET)
        7. 8.5.1.7  SPI Communication Frames
        8. 8.5.1.8  SPI Communication Words
        9. 8.5.1.9  Short SPI Frames
        10. 8.5.1.10 Communication Cyclic Redundancy Check (CRC)
        11. 8.5.1.11 SPI Timeout
      2. 8.5.2 ADC Conversion Data
      3. 8.5.3 Commands
        1. 8.5.3.1 NULL (0000 0000 0000 0000)
        2. 8.5.3.2 RESET (0000 0000 0001 0001)
        3. 8.5.3.3 STANDBY (0000 0000 0010 0010)
        4. 8.5.3.4 WAKEUP (0000 0000 0011 0011)
        5. 8.5.3.5 LOCK (0000 0101 0101 0101)
        6. 8.5.3.6 UNLOCK (0000 0110 0101 0101)
        7. 8.5.3.7 RREG (101a aaaa annn nnnn)
          1. 8.5.3.7.1 Reading a Single Register
          2. 8.5.3.7.2 Reading Multiple Registers
        8. 8.5.3.8 WREG (011a aaaa annn nnnn)
      4. 8.5.4 ADC Output Buffer and FIFO Buffer
      5. 8.5.5 Collecting Data for the First Time or After a Pause in Data Collection
    6. 8.6 AMC131M01 Registers
  10. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Unused Inputs and Outputs
      2. 9.1.2 Antialiasing
      3. 9.1.3 Minimum Interface Connections
      4. 9.1.4 Multiple Device Configuration
      5. 9.1.5 Calibration
      6. 9.1.6 Troubleshooting
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Current Shunt Measurement
      3. 9.2.3 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

ADC Output Buffer and FIFO Buffer

As shown in Figure 8-26, the AMC131M01 has two internal data buffers holding conversion data: an ADC output buffer and a FIFO buffer. Each buffer can only hold one conversion result at a time. The data output on DOUT is always from the FIFO buffer.

GUID-20230327-SS0I-NSRC-TBVX-KM5KD5KX4JHP-low.svg Figure 8-25 ADC Data Output Buffer Structure

Whenever the ADC generates new conversion data, the ADC output buffer is updated immediately with the new data. However, updating the FIFO buffer depends on the previous conversion data retrieval by the host. There are three scenarios:

  • If conversion data (N) stored in the FIFO buffer has already been read by the host at the time that new conversion data (N+1) become available, then the FIFO buffer is updated with the new conversion data (N+1). In this case, data in both the ADC output buffer and the FIFO buffer are updated at the same time (that is, both buffers now hold the same conversion data N+1).
  • If conversion data (N) stored in the FIFO buffer has not yet been read by the host when new conversion data (N+1) become available, then the FIFO buffer is not updated and still holds the previous conversion data (N), while the ADC output buffer now holds the new conversion data (N+1). In this case, data content is different between the ADC output buffer (N+1) and the FIFO buffer (N). After the host reads conversion data N from the FIFO buffer, the FIFO buffer is updated with the conversion data N+1. The host can then retrieve conversion data N+1.
  • A special scenario exists if conversion data (N) stored in the FIFO buffer has not been read by the host, but two new conversion data already became available in the meantime (that is, the ADC output buffer is updated with conversion data N+2). In this case, the FIFO buffer is updated with conversion result N+2 at the same time the ADC output buffer is updated with conversion result N+2 (that is, both buffers now hold the same conversion data N+2). That means, conversion data N and N+1 are lost and cannot be retrieved by the host anymore.

Table 8-10 summarizes the ADC output buffer and FIFO buffer operation when new conversion data (N+1) are available.

Table 8-10 New Conversion Data Available: Operation of the ADC Output Buffer and FIFO Buffer
SPI HISTORY NEW CONVERSION DATA AVAILABLE AT TIME t = tS ADC OUTPUT BUFFER CONTENT (t < tS) FIFO BUFFER CONTENT (t < tS) ADC OUTPUT BUFFER CONTENT (t > tS) FIFO BUFFER CONTENT (t > tS)
FIFO data N has been read by the host N+1 N N N+1 N+1
FIFO data N has not yet been read by the host N+1 N N N+1 N
FIFO data N has not yet been read by the host N+2 N+1 N N+2 N+2

The following three examples illustrate the behavior of the ADC output and FIFO buffer using a simplified notation to indicate which conversion data is stored in each buffer: [number of sample in the ADC output buffer | number of sample in the FIFO buffer].

Example 1: Host reads conversion results as soon as the results become available

  • When the first conversion (result 1) completes, this result is placed both in the ADC output buffer and the FIFO buffer [1 | 1].
  • If the host reads conversion result 1 immediately after the conversion completes, the content of the buffers stays at [1 | 1]. The host can read conversion result 1 from the FIFO buffer multiple times if needed before conversion result 2 completes.
  • When conversion result 2 completes, the result is again placed into both the ADC output buffer and the FIFO buffer [2 | 2].
  • If the host reads the result before the third conversion completes, result 2 is read out and the buffers stay at [2 | 2].

Example 2: Host misses reading one conversion result

  • When the first conversion (result 1) completes, the result is placed both in the ADC output buffer and the FIFO buffer [1 | 1].
  • If the host misses reading result 1 from the FIFO buffer before the second conversion completes, then the ADC output buffer holds result 2, and the FIFO buffer still holds result 1 [2 | 1].
  • If the host now reads data before the third conversion completes, result 1 is read. The content of the buffers then updates to [2 | 2].
  • Another conversion data read request by the host shifts out result 2 on DOUT. The buffers stay at [2 | 2].
  • Now when the third conversion completes, both buffers update with result 3 [3 | 3].

Example 3: Host misses reading two consecutive conversion results

  • When the first conversion (result 1) completes, the result is placed both in the ADC output buffer and the FIFO buffer [1 | 1].
  • If the host misses reading result 1 from the FIFO buffer before the second conversion completes, then the ADC output buffer holds result 2, and the FIFO buffer still holds result 1 [2 | 1].
  • Now if the third conversion completes and the host still did not retrieve data from the FIFO buffer, then result 3 overwrites the data in both the ADC output and FIFO buffer [3 | 3].
  • In this case, both conversion result 1 and result 2 are lost and cannot be read anymore by the host.

Resulting from the internal structure of the ADC, including the ADC output buffer and the FIFO buffer, the DRDY pin behaves as described:

  • If conversion data are read by the host every time new conversion data become available, then DRDY follows the format described in the Data Ready (DRDY) section, depending on the DRDY_FMT bit in the MODE register: When the DRDY_FMT bit is 0b, new data are indicated by DRDY changing from high to low and remaining low until either all conversion data are shifted out of the device, or remaining low and going high briefly before the next time DRDY transitions low. When the DRDY_FMT bit is 1b, new data are indicated by a short negative pulse on the DRDY pin.
  • If the DRDY_FMT bit is 0b and the host does not read conversion data from the FIFO buffer before the next conversion completes, then DRDY remains low and goes high briefly before the next time DRDY transitions low (indicating a new conversion).
  • If the DRDY_FMT bit is 1b and the host does not read conversion data from the FIFO buffer before the next conversion completes, then the device skips one DRDY pulse and does not provide another DRDY pulse until the second following instance when data are ready. Therefore, if the DRDY_FMT bit is 1b and the host does not read conversion data at all, the DRDY pin toggles at a rate which is half the conversion rate.