SCPS260C August   2017  – February 2022 TIC12400-Q1

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 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  VS Pin
      2. 8.3.2  VDD Pin
      3. 8.3.3  Device Initialization
      4. 8.3.4  Device Trigger
      5. 8.3.5  Device Reset
        1. 8.3.5.1 VS Supply POR
        2. 8.3.5.2 Hardware Reset
        3. 8.3.5.3 Software Reset
      6. 8.3.6  VS Under-Voltage (UV) Condition
      7. 8.3.7  VS Over-Voltage (OV) Condition
      8. 8.3.8  Switch Inputs Settings
        1. 8.3.8.1 Input Current Source and Sink Selection
        2. 8.3.8.2 Input Mode Selection
        3. 8.3.8.3 Input Enable Selection
        4. 8.3.8.4 Thresholds Adjustment
        5. 8.3.8.5 Wetting Current Configuration
      9. 8.3.9  Interrupt Generation and INT Assertion
        1. 8.3.9.1 INT Pin Assertion Scheme
        2. 8.3.9.2 Interrupt Idle Time (tINT_IDLE) Time
        3. 8.3.9.3 Microcontroller Wake-Up
        4. 8.3.9.4 Interrupt Enable or Disable and Interrupt Generation Conditions
        5. 8.3.9.5 Detection Filter
      10. 8.3.10 Temperature Monitor
        1. 8.3.10.1 Temperature Warning (TW)
        2. 8.3.10.2 Temperature Shutdown (TSD)
      11. 8.3.11 Parity Check and Parity Generation
      12. 8.3.12 Cyclic Redundancy Check (CRC)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Continuous Mode
      2. 8.4.2 Polling Mode
        1. 8.4.2.1 Standard Polling
        2. 8.4.2.2 Matrix polling
      3. 8.4.3 Additional Features
        1. 8.4.3.1 Clean Current Polling (CCP)
        2. 8.4.3.2 Wetting Current Auto-Scaling
        3. 8.4.3.3 VS Measurement
        4. 8.4.3.4 Wetting Current Diagnostic
        5. 8.4.3.5 ADC Self-Diagnostic
    5. 8.5 Programming
      1. 8.5.1 SPI Communication Interface Buses
        1. 8.5.1.1 Chip Select ( CS)
        2. 8.5.1.2 System Clock (SCLK)
        3. 8.5.1.3 Slave In (SI)
        4. 8.5.1.4 Slave Out (SO)
      2. 8.5.2 SPI Sequence
        1. 8.5.2.1 Read Operation
        2. 8.5.2.2 Write Operation
        3. 8.5.2.3 Status Flag
    6. 8.6 Register Maps
    7. 8.7 Programming Guidelines
  9. 9 Application Information Disclaimer
    1. 9.1 Application Information
    2. 9.2 Using TIC12400-Q1 in a 12 V Automotive System
    3. 9.3 Resistor-coded Switches Detection in Automotive Body Control Module
      1. 9.3.1 Design Requirements
      2. 9.3.2 Detailed Design Procedure
      3. 9.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

8.3.12 Cyclic Redundancy Check (CRC)

The TIC12400-Q1 includes a CRC module to support redundancy checks on the configuration registers to ensure the integrity of data. The CRC calculation is based on the ITU-T X.25 implementation, and the CRC polynomial (0x1021) used is popularly known as CRC-CCITT-16 since it was initially proposed by the ITU-T (formerly CCITT) committee. The CRC calculation rule is defined in Table 8-5:

Table 8-5 CRC Calculation Rule
CRC RULEVALUE
CRC result width16 bits
Polynomialx16 + x12 + x5 +1 (1021h)
Initial (seed) valueFFFFh
Input data reflectedNo
Result data reflectedNo
XOR value0000h

The CRC calculation is done on all the configuration registers starting from register CONFIG and ending at register MODE. The device substitutes a zero for each reserved configuration register bit during the CRC calculation. The CRC calculation can be triggered by asserting the CRC_T bit in the CONFIG register. Once completed, the CRC_CALC interrupt bit in the INT_STAT register is asserted and an interrupt is issued. The 16-bit CRC calculation result is stored in the register CRC. This interrupt can be disabled by de-asserting the CRC_CALC_EN bit in the INT_EN_CFG0 register. It is important to avoid writing data to the configuration registers when the device is undergoing CRC calculations to prevent false calculation results.

Figure 8-10 shows the block diagram of the CRC module. The module consists of 16 shift-registers and 3 exclusive-OR gates. The registers start with 1111-1111-1111-1111 (or FFFFh) and the module performs an XOR function and shifts its content until the last bit of the register string is used. The final register’s content after the last data bit is the calculated CRC value of the data set and the content is stored in the CRC register.

Note the CRC_T bit self-clears after the CRC calculation is completed. Logic 1 is used for CRC_T bit during CRC calculation.

GUID-46981292-6B09-4119-932D-66F23D9C36C7-low.gifFigure 8-10 CCITT-16 CRC Module Block Diagram