SNVSCF5B June   2023  – March 2025 TPS35

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  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  Thermal Information
    6. 6.6  Electrical Characteristics
    7. 6.7  Timing Requirements
    8. 6.8  Switching Characteristics
    9. 6.9  Timing Diagrams
    10. 6.10 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Voltage Supervisor
      2. 7.3.2 Timeout Watchdog Timer
        1. 7.3.2.1 tWD Timer
        2. 7.3.2.2 Watchdog Enable Disable Operation
        3. 7.3.2.3 tSD Watchdog Start Up Delay
        4. 7.3.2.4 SET Pin Behavior
      3. 7.3.3 Manual RESET
      4. 7.3.4 RESET and WDO Output
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Output Assert Delay
        1. 8.1.1.1 Factory-Programmed Output Assert Delay Timing
        2. 8.1.1.2 Adjustable Capacitor Timing
      2. 8.1.2 Watchdog Timer Functionality
        1. 8.1.2.1 Factory-Programmed Timing Options
        2. 8.1.2.2 Adjustable Capacitor Timing
    2. 8.2 Typical Applications
      1. 8.2.1 Design 1: Monitoring a Microcontroller Supply Voltage and Watchdog Timer
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Setting the Voltage Threshold
          2. 8.2.1.2.2 Meeting the Watchdog Timeout Period
          3. 8.2.1.2.3 Setting the Reset Delay
          4. 8.2.1.2.4 Setting the Startup Delay and Output Topology
          5. 8.2.1.2.5 Calculating the RESET Pullup Resistor
    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 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
8.2.1.2.1 Setting the Voltage Threshold

The negative-going threshold voltage, VIT-, is set by the device variant. Equation 4 shows how to calculate the "Threshold Voltage" section of the orderable part number.

Equation 4. OPN "Threshold Voltage" number = (VIT- - 1) / 0.05

In this example, the nominal supply voltage for the microcontroller is 1.8V. The minimum supply voltage is 10% lower than the nominal supply voltage, or 1.62V. Setting a 1.65V threshold makes sure that the device resets just before the supply voltage reaches the minimum allowed. Thus a 1.65V threshold is chosen and, using Equation 4, the part number is reduced to TPS35xx13xxxxxxx. Since the hysteresis is 5% typical, the positive-going threshold voltage, VIT+, is 1.73V.