SLVSGE9A november   2022  – april 2023 TPS36-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison
  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 Timing Diagrams
    9. 7.9 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Voltage Supervisor
      2. 8.3.2 Window Watchdog Timer
        1. 8.3.2.1 tWC (Close Window) Timer
        2. 8.3.2.2 tWO (Open Window) Timer
        3. 8.3.2.3 Watchdog Enable Disable Operation
        4. 8.3.2.4 tSD Watchdog Start Up Delay
        5. 8.3.2.5 SET Pin Behavior
      3. 8.3.3 Manual RESET
      4. 8.3.4 RESET and WDO Output
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 CRST Delay
        1. 9.1.1.1 Factory-Programmed Reset Delay Timing
        2. 9.1.1.2 Adjustable Capacitor Timing
      2. 9.1.2 Watchdog Window Functionality
        1. 9.1.2.1 Factory-Programmed watchdog Timing
        2. 9.1.2.2 Adjustable Capacitor Timing
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1: Monitoring Microcontroller Supply and Watchdog During Operational and Sleep Modes
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Setting Voltage Threshold
          2. 9.2.1.2.2 Determining Window Timings During Operation and Sleep Modes
          3. 9.2.1.2.3 Meeting the Minimum Reset Delay
          4. 9.2.1.2.4 Setting the Watchdog Window
          5. 9.2.1.2.5 Calculating the RESET Pullup Resistor
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  10. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  11. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.2.3 Watchdog Enable Disable Operation

The TPS36-Q1 supports watchdog enable or disable functionality. This functionality is critical for different use cases as listed below.

  • Disable watchdog during firmware update to avoid host RESET.
  • Disable watchdog during software step-by-step debug operation.
  • Disable watchdog when performing critical task to avoid watchdog error interrupt.
  • Keep watchdog disabled until host boots up.

The TPS36-Q1 supports watchdog enable or disable functionality through either WD-EN pin (pin configuration C,D) or SET[1:0] = 0b'01 (pin configuration B) logic combination. For a given pinout only one of these two methods is available for the user to disable watchdog operation.

For a pinout which offers a WD-EN pin, the watchdog enable disable functionality is controlled by the logic state of WD-EN pin. Drive WD-EN = 1 to enable the watchdog operation or drive WD-EN = 0 to disable the watchdog operation. The WD-EN pin can be toggled any time during the device operation. The Figure 8-7 diagram shows timing behavior with WD-EN pin control.

GUID-20220722-SS0I-LW48-KJR3-GRZCR09SRT9N-low.svg Figure 8-7 Watchdog Enable: WD-EN Pin Control

SET[1:0] = 0b'01 combination can be used to disable watchdog operation with a pinout which offers SET1 and SET0 pins, but does not include WD-EN pin. The SET pin logic states can be changed at any time during watchdog operation. Refer Section 8.3.2.5 section for additional details regarding SET[1:0] pin behavior.

Pinout options A, B offer watchdog timer control using a capacitance connected between CWD and GND pin. A capacitance value higher than recommended or connect to GND leads to watchdog functionality getting disabled. Capacitance based disable operation overrides the other two options mentioned above. Changing capacitance on the fly does not enable or disable watchdog operation. A power supply recycle or device recovery after UV fault, MR low event is needed to detect change in capacitance.

Ongoing watchdog frame is terminated when watchdog is disabled. WDO stays deasserted when watchdog operation is disabled. For a pinout with only RESET output, the RESET can assert if supply supervisor error occurs. When enabled the device immediately enters tWC frame and start watchdog monitoring operation.