SLASEC8B February   2017  – January 2019 PGA460-Q1

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Typical Application Diagram (Transformer Drive)
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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  Internal Supply Regulators Characteristics
    6. 6.6  Transducer Driver Characteristics
    7. 6.7  Transducer Receiver Characteristics
    8. 6.8  Analog to Digital Converter Characteristics
    9. 6.9  Digital Signal Processing Characteristics
    10. 6.10 Temperature Sensor Characteristics
    11. 6.11 High-Voltage I/O Characteristics
    12. 6.12 Digital I/O Characteristics
    13. 6.13 EEPROM Characteristics
    14. 6.14 Timing Requirements
    15. 6.15 Switching Characteristics
    16. 6.16 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Power-Supply Block
      2. 7.3.2  Burst Generation
        1. 7.3.2.1 Using Center-Tap Transformer
        2. 7.3.2.2 Direct Drive
        3. 7.3.2.3 Other Configurations
      3. 7.3.3  Analog Front-End
      4. 7.3.4  Digital Signal Processing
        1. 7.3.4.1 Ultrasonic Echo—Band-Pass Filter
        2. 7.3.4.2 Ultrasonic Echo–Rectifier, Peak Hold, Low-Pass Filter, and Data Selection
        3. 7.3.4.3 Ultrasonic Echo—Nonlinear Scaling
        4. 7.3.4.4 Ultrasonic Echo—Threshold Data Assignment
        5. 7.3.4.5 Digital Gain
      5. 7.3.5  System Diagnostics
        1. 7.3.5.1 Device Internal Diagnostics
      6. 7.3.6  Interface Description
        1. 7.3.6.1 Time-Command Interface
          1. 7.3.6.1.1 RUN Commands
          2. 7.3.6.1.2 CONFIGURATION/STATUS Command
        2. 7.3.6.2 USART Interface
          1. 7.3.6.2.1 USART Asynchronous Mode
            1. 7.3.6.2.1.1 Sync Field
            2. 7.3.6.2.1.2 Command Field
            3. 7.3.6.2.1.3 Data Fields
            4. 7.3.6.2.1.4 Checksum Field
            5. 7.3.6.2.1.5 PGA460-Q1 UART Commands
            6. 7.3.6.2.1.6 UART Operations
              1. 7.3.6.2.1.6.1 No-Response Operation
              2. 7.3.6.2.1.6.2 Response Operation (All Except Register Read)
              3. 7.3.6.2.1.6.3 Response Operation (Register Read)
            7. 7.3.6.2.1.7 Diagnostic Field
            8. 7.3.6.2.1.8 USART Synchronous Mode
          2. 7.3.6.2.2 One-Wire UART Interface
          3. 7.3.6.2.3 Ultrasonic Object Detection Through UART Operations
        3. 7.3.6.3 In-System IO-Pin Interface Selection
      7. 7.3.7  Echo Data Dump
        1. 7.3.7.1 On-Board Memory Data Store
        2. 7.3.7.2 Direct Data Burst Through USART Synchronous Mode
      8. 7.3.8  Low-Power Mode
        1. 7.3.8.1 Time-Command Interface
        2. 7.3.8.2 UART Interface
      9. 7.3.9  Transducer Time and Temperature Decoupling
        1. 7.3.9.1 Time Decoupling
        2. 7.3.9.2 Temperature Decoupling
      10. 7.3.10 Memory CRC Calculation
      11. 7.3.11 Temperature Sensor and Temperature Data-Path
      12. 7.3.12 TEST Pin Functionality
    4. 7.4 Device Functional Modes
    5. 7.5 Programming
      1. 7.5.1 UART and USART Communication Examples
    6. 7.6 Register Maps
      1. 7.6.1 EEPROM Programming
      2. 7.6.2 Register Map Partitioning and Default Values
      3. 7.6.3 REGMAP Registers
        1. 7.6.3.1  USER_DATA1 Register (Address = 0h) [reset = 0h]
          1. Table 9. USER_DATA1 Register Field Descriptions
        2. 7.6.3.2  USER_DATA2 Register (Address = 1h) [reset = 0h]
          1. Table 10. USER_DATA2 Register Field Descriptions
        3. 7.6.3.3  USER_DATA3 Register (Address = 2h) [reset = 0h]
          1. Table 11. USER_DATA3 Register Field Descriptions
        4. 7.6.3.4  USER_DATA4 Register (Address = 3h) [reset = 0h]
          1. Table 12. USER_DATA4 Register Field Descriptions
        5. 7.6.3.5  USER_DATA5 Register (Address = 4h) [reset = 0h]
          1. Table 13. USER_DATA5 Register Field Descriptions
        6. 7.6.3.6  USER_DATA6 Register (Address = 5h) [reset = 0h]
          1. Table 14. USER_DATA6 Register Field Descriptions
        7. 7.6.3.7  USER_DATA7 Register (Address = 6h) [reset = 0h]
          1. Table 15. USER_DATA7 Register Field Descriptions
        8. 7.6.3.8  USER_DATA8 Register (Address = 7h) [reset = 0h]
          1. Table 16. USER_DATA8 Register Field Descriptions
        9. 7.6.3.9  USER_DATA9 Register (Address = 8h) [reset = 0h]
          1. Table 17. USER_DATA9 Register Field Descriptions
        10. 7.6.3.10 USER_DATA10 Register (Address = 9h) [reset = 0h]
          1. Table 18. USER_DATA10 Register Field Descriptions
        11. 7.6.3.11 USER_DATA11 Register (Address = Ah) [reset = 0h]
          1. Table 19. USER_DATA11 Register Field Descriptions
        12. 7.6.3.12 USER_DATA12 Register (Address = Bh) [reset = 0h]
          1. Table 20. USER_DATA12 Register Field Descriptions
        13. 7.6.3.13 USER_DATA13 Register (Address = Ch) [reset = 0h]
          1. Table 21. USER_DATA13 Register Field Descriptions
        14. 7.6.3.14 USER_DATA14 Register (Address = Dh) [reset = 0h]
          1. Table 22. USER_DATA14 Register Field Descriptions
        15. 7.6.3.15 USER_DATA15 Register (Address = Eh) [reset = 0h]
          1. Table 23. USER_DATA15 Register Field Descriptions
        16. 7.6.3.16 USER_DATA16 Register (Address = Fh) [reset = 0h]
          1. Table 24. USER_DATA16 Register Field Descriptions
        17. 7.6.3.17 USER_DATA17 Register (Address = 10h) [reset = 0h]
          1. Table 25. USER_DATA17 Register Field Descriptions
        18. 7.6.3.18 USER_DATA18 Register (Address = 11h) [reset = 0h]
          1. Table 26. USER_DATA18 Register Field Descriptions
        19. 7.6.3.19 USER_DATA19 Register (Address = 12h) [reset = 0h]
          1. Table 27. USER_DATA19 Register Field Descriptions
        20. 7.6.3.20 USER_DATA20 Register (Address = 13h) [reset = 0h]
          1. Table 28. USER_DATA20 Register Field Descriptions
        21. 7.6.3.21 TVGAIN0 Register (Address = 14h) [reset = 0h]
          1. Table 29. TVGAIN0 Register Field Descriptions
        22. 7.6.3.22 TVGAIN1 Register (Address = 15h) [reset = 0h]
          1. Table 30. TVGAIN1 Register Field Descriptions
        23. 7.6.3.23 TVGAIN2 Register (Address = 16h) [reset = 0h]
          1. Table 31. TVGAIN2 Register Field Descriptions
        24. 7.6.3.24 TVGAIN3 Register (Address = 17h) [reset = 0h]
          1. Table 32. TVGAIN3 Register Field Descriptions
        25. 7.6.3.25 TVGAIN4 Register (Address = 18h) [reset = 0h]
          1. Table 33. TVGAIN4 Register Field Descriptions
        26. 7.6.3.26 TVGAIN5 Register (Address = 19h) [reset = 0h]
          1. Table 34. TVGAIN5 Register Field Descriptions
        27. 7.6.3.27 TVGAIN6 Register (Address = 1Ah) [reset = 0h]
          1. Table 35. TVGAIN6 Register Field Descriptions
        28. 7.6.3.28 INIT_GAIN Register (Address = 1Bh) [reset = 0h]
          1. Table 36. INIT_GAIN Register Field Descriptions
        29. 7.6.3.29 FREQUENCY Register (Address = 1Ch) [reset = 0h]
          1. Table 37. FREQUENCY Register Field Descriptions
        30. 7.6.3.30 DEADTIME Register (Address = 1Dh) [reset = 0h]
          1. Table 38. DEADTIME Register Field Descriptions
        31. 7.6.3.31 PULSE_P1 Register (Address = 1Eh) [reset = 0h]
          1. Table 39. PULSE_P1 Register Field Descriptions
        32. 7.6.3.32 PULSE_P2 Register (Address = 1Fh) [reset = 0h]
          1. Table 40. PULSE_P2 Register Field Descriptions
        33. 7.6.3.33 CURR_LIM_P1 Register (Address = 20h) [reset = 0h]
          1. Table 41. CURR_LIM_P1 Register Field Descriptions
        34. 7.6.3.34 CURR_LIM_P2 Register (Address = 21h) [reset = 0h]
          1. Table 42. CURR_LIM_P2 Register Field Descriptions
        35. 7.6.3.35 REC_LENGTH Register (Address = 22h) [reset = 0h]
          1. Table 43. REC_LENGTH Register Field Descriptions
        36. 7.6.3.36 FREQ_DIAG Register (Address = 23h) [reset = 0h]
          1. Table 44. FREQ_DIAG Register Field Descriptions
        37. 7.6.3.37 SAT_FDIAG_TH Register (Address = 24h) [reset = 0h]
          1. Table 45. SAT_FDIAG_TH Register Field Descriptions
        38. 7.6.3.38 FVOLT_DEC Register (Address = 25h) [reset = 0h]
          1. Table 46. FVOLT_DEC Register Field Descriptions
        39. 7.6.3.39 DECPL_TEMP Register (Address = 26h) [reset = 0h]
          1. Table 47. DECPL_TEMP Register Field Descriptions
        40. 7.6.3.40 DSP_SCALE Register (Address = 27h) [reset = 0h]
          1. Table 48. DSP_SCALE Register Field Descriptions
        41. 7.6.3.41 TEMP_TRIM Register (Address = 28h) [reset = 0h]
          1. Table 49. TEMP_TRIM Register Field Descriptions
        42. 7.6.3.42 P1_GAIN_CTRL Register (Address = 29h) [reset = 0h]
          1. Table 50. P1_GAIN_CTRL Register Field Descriptions
        43. 7.6.3.43 P2_GAIN_CTRL Register (Address = 2Ah) [reset = 0h]
          1. Table 51. P2_GAIN_CTRL Register Field Descriptions
        44. 7.6.3.44 EE_CRC Register (Address = 2Bh) [reset = 0h]
          1. Table 52. EE_CRC Register Field Descriptions
        45. 7.6.3.45 EE_CNTRL Register (Address = 40h) [reset = 00h]
          1. Table 53. EE_CNTRL Register Field Descriptions
        46. 7.6.3.46 BPF_A2_MSB Register (Address = 41h) [reset = 00h]
          1. Table 54. BPF_A2_MSB Register Field Descriptions
        47. 7.6.3.47 BPF_A2_LSB Register (Address = 42h) [reset = 00h]
          1. Table 55. BPF_A2_LSB Register Field Descriptions
        48. 7.6.3.48 BPF_A3_MSB Register (Address = 43h) [reset = 00h]
          1. Table 56. BPF_A3_MSB Register Field Descriptions
        49. 7.6.3.49 BPF_A3_LSB Register (Address = 44h) [reset = 00h]
          1. Table 57. BPF_A3_LSB Register Field Descriptions
        50. 7.6.3.50 BPF_B1_MSB Register (Address = 45h) [reset = 00h]
          1. Table 58. BPF_B1_MSB Register Field Descriptions
        51. 7.6.3.51 BPF_B1_LSB Register (Address = 46h) [reset = 00h]
          1. Table 59. BPF_B1_LSB Register Field Descriptions
        52. 7.6.3.52 LPF_A2_MSB Register (Address = 47h) [reset = 00h]
          1. Table 60. LPF_A2_MSB Register Field Descriptions
        53. 7.6.3.53 LPF_A2_LSB Register (Address = 48h) [reset = 00h]
          1. Table 61. LPF_A2_LSB Register Field Descriptions
        54. 7.6.3.54 LPF_B1_MSB Register (Address = 49h) [reset = 00h]
          1. Table 62. LPF_B1_MSB Register Field Descriptions
        55. 7.6.3.55 LPF_B1_LSB Register (Address = 4Ah) [reset = 00h]
          1. Table 63. LPF_B1_LSB Register Field Descriptions
        56. 7.6.3.56 TEST_MUX Register (Address = 4Bh) [reset = 00h]
          1. Table 64. TEST_MUX Register Field Descriptions
        57. 7.6.3.57 DEV_STAT0 Register (Address = 4Ch) [reset = 84h]
          1. Table 65. DEV_STAT0 Register Field Descriptions
        58. 7.6.3.58 DEV_STAT1 Register (Address = 4Dh) [reset = 00h]
          1. Table 66. DEV_STAT1 Register Field Descriptions
        59. 7.6.3.59 P1_THR_0 Register (Address = 5Fh) [reset = X]
          1. Table 67. P1_THR_0 Register Field Descriptions
        60. 7.6.3.60 P1_THR_1 Register (Address = 60h) [reset = X]
          1. Table 68. P1_THR_1 Register Field Descriptions
        61. 7.6.3.61 P1_THR_2 Register (Address = 61h) [reset = X]
          1. Table 69. P1_THR_2 Register Field Descriptions
        62. 7.6.3.62 P1_THR_3 Register (Address = 62h) [reset = X]
          1. Table 70. P1_THR_3 Register Field Descriptions
        63. 7.6.3.63 P1_THR_4 Register (Address = 63h) [reset = X]
          1. Table 71. P1_THR_4 Register Field Descriptions
        64. 7.6.3.64 P1_THR_5 Register (Address = 64h) [reset = X]
          1. Table 72. P1_THR_5 Register Field Descriptions
        65. 7.6.3.65 P1_THR_6 Register (Address = 65h) [reset = X]
          1. Table 73. P1_THR_6 Register Field Descriptions
        66. 7.6.3.66 P1_THR_7 Register (Address = 66h) [reset = X]
          1. Table 74. P1_THR_7 Register Field Descriptions
        67. 7.6.3.67 P1_THR_8 Register (Address = 67h) [reset = X]
          1. Table 75. P1_THR_8 Register Field Descriptions
        68. 7.6.3.68 P1_THR_9 Register (Address = 68h) [reset = X]
          1. Table 76. P1_THR_9 Register Field Descriptions
        69. 7.6.3.69 P1_THR_10 Register (Address = 69h) [reset = X]
          1. Table 77. P1_THR_10 Register Field Descriptions
        70. 7.6.3.70 P1_THR_11 Register (Address = 6Ah) [reset = X]
          1. Table 78. P1_THR_11 Register Field Descriptions
        71. 7.6.3.71 P1_THR_12 Register (Address = 6Bh) [reset = X]
          1. Table 79. P1_THR_12 Register Field Descriptions
        72. 7.6.3.72 P1_THR_13 Register (Address = 6Ch) [reset = X]
          1. Table 80. P1_THR_13 Register Field Descriptions
        73. 7.6.3.73 P1_THR_14 Register (Address = 6Dh) [reset = X]
          1. Table 81. P1_THR_14 Register Field Descriptions
        74. 7.6.3.74 P1_THR_15 Register (Address = 6Eh) [reset = X]
          1. Table 82. P1_THR_15 Register Field Descriptions
        75. 7.6.3.75 P2_THR_0 Register (Address = 6Fh) [reset = X]
          1. Table 83. P2_THR_0 Register Field Descriptions
        76. 7.6.3.76 P2_THR_1 Register (Address = 70h) [reset = X]
          1. Table 84. P2_THR_1 Register Field Descriptions
        77. 7.6.3.77 P2_THR_2 Register (Address = 71h) [reset = X]
          1. Table 85. P2_THR_2 Register Field Descriptions
        78. 7.6.3.78 P2_THR_3 Register (Address = 72h) [reset = X]
          1. Table 86. P2_THR_3 Register Field Descriptions
        79. 7.6.3.79 P2_THR_4 Register (Address = 73h) [reset = X]
          1. Table 87. P2_THR_4 Register Field Descriptions
        80. 7.6.3.80 P2_THR_5 Register (Address = 74h) [reset = X]
          1. Table 88. P2_THR_5 Register Field Descriptions
        81. 7.6.3.81 P2_THR_6 Register (Address = 75h) [reset = X]
          1. Table 89. P2_THR_6 Register Field Descriptions
        82. 7.6.3.82 P2_THR_7 Register (Address = 76h) [reset = X]
          1. Table 90. P2_THR_7 Register Field Descriptions
        83. 7.6.3.83 P2_THR_8 Register (Address = 77h) [reset = X]
          1. Table 91. P2_THR_8 Register Field Descriptions
        84. 7.6.3.84 P2_THR_9 Register (Address = 78h) [reset = X]
          1. Table 92. P2_THR_9 Register Field Descriptions
        85. 7.6.3.85 P2_THR_10 Register (Address = 79h) [reset = X]
          1. Table 93. P2_THR_10 Register Field Descriptions
        86. 7.6.3.86 P2_THR_11 Register (Address = 7Ah) [reset = X]
          1. Table 94. P2_THR_11 Register Field Descriptions
        87. 7.6.3.87 P2_THR_12 Register (Address = 7Bh) [reset = X]
          1. Table 95. P2_THR_12 Register Field Descriptions
        88. 7.6.3.88 P2_THR_13 Register (Address = 7Ch) [reset = X]
          1. Table 96. P2_THR_13 Register Field Descriptions
        89. 7.6.3.89 P2_THR_14 Register (Address = 7Dh) [reset = X]
          1. Table 97. P2_THR_14 Register Field Descriptions
        90. 7.6.3.90 P2_THR_15 Register (Address = 7Eh) [reset = X]
          1. Table 98. P2_THR_15 Register Field Descriptions
        91. 7.6.3.91 THR_CRC Register (Address = 7Fh) [reset = X]
          1. Table 99. THR_CRC Register Field Descriptions
  8. Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Transducer Types
    2. 8.2 Typical Applications
      1. 8.2.1 Transformer-Driven Method
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Transducer Driving Voltage
          2. 8.2.1.2.2 Transducer Driving Frequency
          3. 8.2.1.2.3 Transducer Pulse Count
          4. 8.2.1.2.4 Transformer Turns Ratio
          5. 8.2.1.2.5 Transformer Saturation Current and Main Voltage Rating
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Direct-Driven (Transformer-Less) Method
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

System Diagnostics

The system diagnostics in the PGA460-Q1 device help characterize the transducer element during the burst itself and determine the status of the overall system. By using the provided information the system should be able to detect transducer failure, driver-circuit failure (transformer failure if used), environmental effects on the system (such as ice, dirt, snow), objects compromising the transducer operation (such as pressure applied to the transducer), and others.

Three implemented system diagnostics are available in the PGA460-Q1 device that provide information which can be used in detecting system flaws. These diagnostics are described as follows:

    Voltage diagnostic measurementThe voltage diagnostic feature is obtained by monitoring the current flowing through the INP pin only when a BURST/LISTEN run command is executed. The transducer excitation voltage at the particular burst frequency results in a current at INP pin that is compared to a reference current with a current comparator as shown in Figure 10. If the excitation current exceeds the threshold level set using the FVOLT_ERR_TH in FVOLT_DEC register, the current comparator output goes high which implies a normal burst with the desired level of excitation voltage. The measurement starts approximately 50 µs after the burst stage is started and ends at the end of the burst stage. The result of this diagnostic measurement is reported in the status frames of the IO time-command or the UART interface as described in the Interface Description section.
    PGA460-Q1 pga460-q1-voltage-diagnostic-measurement.gifFigure 10. Block Diagram for Voltage Diagnostic
    Equation 4. PGA460-Q1 eq_06_vdiag_slasec8.gif

    where

    • FVOLT_ERR_TH[2:0] corresponds to 1 for 000b to 8 for 111b.
    • fburst is the burst frequency in kilohertz.
    • CINP is the input capacitance on the INP pin.
    • RINPis an optional resistor (See Figure 136) used for EMI and ESD robustness.

    NOTE

    Prior to bursting, the comparator output is expected to be low. In the event that the output is stuck high, the condition is detected and the diagnostic fail flag is set

    Transducer frequency measurement During the decay stage of the record interval a frequency measurement on the transducer node is performed to validate the performance and proper tuning of the transformer and transducer matching.

    To measure the transducer frequency, a start parameter, FDIAG_START, and a window length parameter, FDIAG_LEN, are defined in EEPROM memory. The start parameter, FDIAG_START, defines the time when the frequency measurement starts relative to the end of the burst time. The diagnostic window length parameter, FDIAG_LEN, sets the time width of the diagnostic window in terms of signal periods captured. A brief example of parameter configuration can be explained:

    1. Assume FDIAG_START = 2 and FDIAG_LEN = 1. Referring to the Register Maps section, the start time of these EEPROM parameters is determined to be 200 µs after the burst is completed and window length of 3 signal periods. Assuming an operating frequency of 58 kHz, the signal period is 17.24 µs and therefore the diagnostic ends at 200 µs + 3 × 17.24 µs = 251.72 µs after the burst is complete.
    2. The frequency information captured in the measurement window is averaged and expressed as a 500-ns time based counter value. The signal frequency can be calculated using Equation 5.
    3. Equation 5. f = 1 / (FDIAG_VAL × 500e–09)

      where

      • FDIAG_VAL is a value that can be extracted using any of the device interfaces.
    4. If the specified number of objects are detected before a frequency diagnostic measurement completes, no frequency measurement results are saved. This can be managed by setting the previously defined diagnostic parameters and threshold settings for near-object detection.

    An additional frequency error feature is implemented in the PGA460-Q1 device to signify that the measured transducer frequency is outside of the limits set by the FDIAG_ERR_TH threshold parameter. The result of this feature is reported in the status frames of the IO time-command or the UART interface. For more information on reporting the transducer frequency error, see the Interface Description section.

    Decay-period time captureDuring the decay stage of the record interval a transducer decay time measurement is performed to verify correct operation of the transducer. This diagnostic in combination with the transducer frequency measurement are commonly used in ultrasonic systems to detect external blockage of the ultrasonic transducer.

    The decay period time is measured at the output of the digital data path. The measurement starts at the same time when the burst stage is completed and the decay period is measured as long as the echo level is higher than a saturation threshold level defined in the EEPROM by the SAT_TH parameter. The provided result can be extracted by using any of the PGA460-Q1 interfaces, while the value is expressed in 16-µs time increments. If the decay time measured greater than 4 ms, the value extracted will read 0xFF.

    Noise level measurement An additional system diagnostic implemented in the PGA460-Q1 device is the noise-level measurement diagnostic. The purpose of this function is to evaluate the surrounding noise generated by other ultrasonic systems nearby to determine disturbances and also evaluate the noise floor level when far distance objects are being detected.

    During the noise-level measurement, the PGA460-Q1 device executes the LISTEN ONLY (Preset2) command (see the Interface Description section for details of the command) where no burst is performed but only a record interval is started and lasts 8.192 ms. During this record interval, the data collected at the output of the digital data path is averaged into two groups each containing 4096 samples. The final noise level is measured by performing the noise-level measurement function is the higher averaged value of the two groups. This value is reported as the final noise-level measurement.

    NOTE

    The nonlinear scaling block is always disabled (scale factor EEPROM by setting the SCALE_K bit 0 and the NOISE_LVL bit to 0) during the noise-level measurement process.

Figure 11 shows the system diagnostics implemented in the PGA460-Q1 device as a full object-detection record cycle example. The numbers 1, 2, and 3 in Figure 11 show voltage diagnostic, transducer frequency, and decay-period measurement, respectively.

PGA460-Q1 g_systems_diagnostics_slasec8.gifFigure 11. Systems Diagnostics Example