SLVS331I December   2000  – October 2021

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
    1.     6
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 Dissipation Ratings
    9. 7.9 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Input Voltage (VDD)
        1. 8.3.1.1 VDD Hysteresis
        2. 8.3.1.2 VDD Glitch Immunity
      2. 8.3.2 User-Programmable Watchdog Timer (WDI)
      3. 8.3.3 RESET Output
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Operation (VDD > VIT)
      2. 8.4.2 Above Power-On Reset But Less Than Threshold (VPOR < VDD < VIT)
      3. 8.4.3 Below Power-On Reset (VDD < VPOR)
    5. 8.5 Programming
      1. 8.5.1 Implementing Window-Watchdog Settings
      2. 8.5.2 Programmable Window-Watchdog by Using an External Capacitor
      3. 8.5.3 Lower Boundary Calculation
      4. 8.5.4 Watchdog Software Considerations
      5. 8.5.5 Power-Up Considerations
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.1 Overview

The TPS3813xxx family of supervisory circuits provide circuit initialization and timing supervision signals. During power on, RESET is asserted (low) when the supply voltage (VDD) increases above 1.1 V. Thereafter, the supervisory circuit monitors VDD and keeps RESET low as long as VDD remains below the threshold voltage (VIT). Once VDD increases above VIT, an internal timer delays the deassertion of the output to allow for a proper system reset before RESET transitions to a high state. The delay time (td) is 25 ms typical and starts after VDD rises above the VIT. When the supply voltage drops below VIT, the output transitions low again. All the devices of this family have a fixed threshold voltage set by an internal voltage divider.

The TPS3813xxx family incorporates a so-called window-watchdog timer, which has a programmable delay and window ratio. The supervised processor must trigger the WDI pin of the TPS3813xxx within the user-programmable window to keep RESET from asserting. The upper limit of the watchdog time-out can be set by either connecting WDT to GND, VDD, or using an external capacitor. The lower limit and thus the window ratio is set by connecting WDR to GND or VDD.