JAJSFU0A July   2018  – October 2021 TPS3430

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  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
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 CRST
      2. 7.3.2 Window Watchdog
        1. 7.3.2.1 SET0 and SET1
          1. 7.3.2.1.1 Enabling the Window Watchdog
          2. 7.3.2.1.2 Disabling the Watchdog Timer When Using the CRST Capacitor
          3. 7.3.2.1.3 SET0 and SET1 During Normal Watchdog Operation
      3. 7.3.3 Window Watchdog Timer
        1. 7.3.3.1 CWD
        2. 7.3.3.2 WDI Functionality
        3. 7.3.3.3 WDO Functionality
    4. 7.4 Device Functional Modes
      1. 7.4.1 VDD is Below VPOR ( VDD < VPOR)
      2. 7.4.2 VDD is Above VPOR And Below VDD (min)( VPOR < VDD < VDD (min))
      3. 7.4.3 Normal Operation (VDD ≥ VDD (min))
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 CRST Delay
        1. 8.1.1.1 Factory-Programmed Watchdog Reset Delay Timing
        2. 8.1.1.2 CRST Programmable Watchdog Reset Delay
      2. 8.1.2 CWD Functionality
        1. 8.1.2.1 Factory-Programmed Timing Options
        2. 8.1.2.2 CWD Adjustable Capacitor Watchdog Timeout
    2. 8.2 Typical Applications
      1. 8.2.1 Monitoring Microcontroller with Watchdog Timer - Design 1
        1. 8.2.1.1 Design Requirements - Design 1
        2. 8.2.1.2 Detailed Design Procedure - Design 1
          1. 8.2.1.2.1 Meeting the Minimum Watchdog Reset Delay - Design 1
          2. 8.2.1.2.2 Setting the Watchdog Window - Design 1
          3. 8.2.1.2.3 Calculating the WDO Pull-up Resistor - Design 1
      2. 8.2.2 Monitoring Microcontroller with a Programmed Window Watchdog Timer - Design 2
        1. 8.2.2.1 Design Requirements - Design 2
        2. 8.2.2.2 Detailed Design Procedure - Design 2
          1. 8.2.2.2.1 Meeting the Minimum Watchdog Reset Delay - Design 2
          2. 8.2.2.2.2 Setting the Watchdog Window - Design 2
          3. 8.2.2.2.3 Calculating the WDO Pull-up Resistor - Design 2
      3. 8.2.3 Monitoring Microcontroller with a Latching Window Watchdog Timer - Design 3
        1. 8.2.3.1 Design Requirements - Design 3
        2. 8.2.3.2 Detailed Design Procedure - Design 3
          1. 8.2.3.2.1 Meeting the Latching Output Requirement - Design 3
          2. 8.2.3.2.2 Setting the Watchdog Window - Design 3
        3. 8.2.3.3 Application Curve - Design 3
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 サポート・リソース
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

7.3.3.2 WDI Functionality

WDI is the watchdog timer input that controls the WDO output. The WDI input is triggered by the falling edge of the input signal. For the first pulse, the watchdog acts as a traditional watchdog timer; thus, the first pulse must be issued before tWDU(min). After the first pulse, to ensure proper functionality of the watchdog timer, always issue the WDI pulse within the window of tWDL(max) and tWDU(min). If the pulse is issued in this region, then WDO remains unasserted. Otherwise, the device asserts WDO, putting the WDO pin into a low-impedance state.

The watchdog input (WDI) is a digital pin. To ensure there is no increase in IDD, drive the WDI pin to either VDD or GND at all times. Putting the pin to an intermediate voltage can cause an increase in supply current (IDD) because of the architecture of the digital logic gates. When WDO is asserted, the watchdog is disabled and all signals input to WDI are ignored until the WDO reset delay expires. When WDO is no longer asserted, the device resumes normal operation and no longer ignores the signal on WDI. If the watchdog is disabled, drive the WDI pin to either VDD or GND.