SBVS300A November   2016  – September 2021 TPS3851

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  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 Diagram
    3. 7.3 Feature Description
      1. 7.3.1 RESET
      2. 7.3.2 Manual Reset MR
      3. 7.3.3 UV Fault Detection
      4. 7.3.4 Watchdog Mode
        1. 7.3.4.1 CWD
        2. 7.3.4.2 Watchdog Input WDI
        3. 7.3.4.3 Watchdog Output WDO
        4. 7.3.4.4 SET1
    4. 7.4 Device Functional Modes
      1. 7.4.1 VDD is Below VPOR ( VDD < VPOR)
      2. 7.4.2 Above Power-On-Reset, But Less Than 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 CWD Functionality
        1. 8.1.1.1 Factory-Programmed Timing Options
        2. 8.1.1.2 Adjustable Capacitor Timing
      2. 8.1.2 Overdrive Voltage
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Monitoring the 1.8-V Rail
        2. 8.2.2.2 Calculating RESET and WDO Pullup Resistor
        3. 8.2.2.3 Setting the Watchdog
        4. 8.2.2.4 Watchdog Disabled During Initialization Period
      3. 8.2.3 Glitch Immunity
      4. 8.2.4 Application Curves
  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
      1. 11.1.1 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.1.1 CWD Functionality

The TPS3851 features three options for setting the watchdog timer: connecting a capacitor to the CWD pin, connecting a pullup resistor to VDD, and leaving the CWD pin unconnected. Figure 8-1 shows a schematic drawing of all three options. If this pin is connected to VDD through a 10-kΩ pullup resistor or left unconnected (high impedance), then the factory-programmed watchdog timeouts are enabled; see the Section 8.1.1.1 section. Otherwise, the watchdog timeout can be adjusted by placing a capacitor from the CWD pin to ground.

GUID-45AE8B6A-7FC6-426C-8000-678D0F9A91CC-low.gifFigure 8-1 CWD Charging Circuit