SNVSCK5 April   2024 TPS3842

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specification
    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 Timing Diagram
  8. 7 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 SENSE Input
        1. 8.3.1.1 SENSE Hysteresis
      2. 8.3.2 Selecting the SENSE Delay Time
      3. 8.3.3 Selecting the RESET Delay Time
      4. 8.3.4 RESET Output
    4. 8.4 Device Functional Modes
      1. 8.4.1 Normal Operation (VDD > VDD(min))
      2. 8.4.2 Above Power-On Reset but Less Than VDD(min) (VPOR < VDD < VDD(min))
      3. 8.4.3 Below Power-On Reset (VDD < VPOR)
  10. 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
        1. 9.2.2.1 Meeting the Sense and Reset Delay
      3. 9.2.3 Application Curve
      4. 9.2.4 Power Supply Recommendations
      5. 9.2.5 Layout
        1. 9.2.5.1 Layout Guidelines
        2. 9.2.5.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Trademarks
    3. 10.3 Electrostatic Discharge Caution
    4. 10.4 Support Resources
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.2 Detailed Design Procedure

The TPS3842 utilizes high-voltage SENSE and VDD inputs to monitor a 12V power supply for undervoltage. In this design example TPS3842A011DRLR is used.

The negative-going threshold voltage, VITN, is set by the device variant. In this example, the nominal supply voltage from the power supply is 12V. Setting a undervoltage threshold of 9.5V (approximately 20% under 12V) makes sure that the device resets before supply voltage violates the allowed boundary. The adjustable voltage variant is chosen and R1 and R2 are adjusted to meet the threshold. Assuming R2 equal to 10kΩ and R1 is calculated as 125kΩ. For additional information on selecting resistor values see Section 8.3.1. TPS3842 also supports fixed voltage threshold variants. Threshold voltage decoding can be found in Device Decoder.