SLVS331J December   2000  – August 2024 TPS3813

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 Switching Characteristics
    8. 6.8 Dissipation Ratings
    9. 6.9 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Input Voltage (VDD)
        1. 7.3.1.1 VDD Hysteresis
        2. 7.3.1.2 VDD Glitch Immunity
      2. 7.3.2 User-Programmable Watchdog Timer (WDI)
      3. 7.3.3 RESET Output
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation (VDD > VIT)
      2. 7.4.2 Above Power-On Reset But Less Than Threshold (VPOR < VDD < VIT)
      3. 7.4.3 Below Power-On Reset (VDD < VPOR)
    5. 7.5 Programming
      1. 7.5.1 Implementing Window-Watchdog Settings
      2. 7.5.2 Programmable Window-Watchdog by Using an External Capacitor
      3. 7.5.3 Lower Boundary Calculation
      4. 7.5.4 Watchdog Software Considerations
      5. 7.5.5 Power-Up Considerations
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curve
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Related Links
    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
  11. 10Revision History
  12. 11Mechanical, 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

7.5.2 Programmable Window-Watchdog by Using an External Capacitor

The upper boundary of the watchdog timer can be set by an external capacitor connected between the WDT pin and GND. Common consumer electronic capacitors can be used to implement this feature. They must have low ESR, low leakage (< 5nA) and low tolerances because the tolerances have to be considered if the calculations are performed. The first formula is used to calculate the upper window frame. After calculating the upper window frame, the lower boundary can be calculated. As in the last example, the most important values are the tboundary,max and twindow,min. The trigger pulse has to fit into this window frame.

The external capacitor must have a value between a minimum of 155pF and a maximum of 63nF.

Table 7-3 Setting Upper Window Using External Capacitor
SELECTED OPERATION MODEWINDOW FRAME
WDT = external capacitor C(ext)WDR = 0V and WDR = VDDtwindow,max = 1.25 × twindow,typ
twindow,min = 0.75 × twindow,typ
Equation 2. TPS3813