SLVSIB0 December   2025 UCD91320

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Linearity Parameters
    7. 5.7 POR and BOR
    8. 5.8 Low Frequency Crystal/Clock
    9. 5.9 Flash Memory Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Feature Description
      1. 6.2.1 TI Sequencer Studio Software
      2. 6.2.2 PMBUS Interface
      3. 6.2.3 PMBUS Security
    3. 6.3 Device Functional Modes
      1. 6.3.1 Black Box Fault Logging
      2. 6.3.2 PMBus Address Selection
      3. 6.3.3 Brownout
    4.     Failure Analysis and Returns
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.3 Brownout

The UCD91320 device triggers brownout event when the VDD pin voltage drops below the brownout threshold voltage (VBOR). During a brownout event, the device continues to write fault logs into the NVM that occurred before the brownout event. The device fully shuts down when the VDD pin voltage is below the shutdown threshold voltage (VSHDN). Any fault event that has not been written into the NVM before the device shutdown is lost.

If several faults happen immediately before the brownout event, the device requires a capacitance of 500 µs to write the first fault event into the NVM. The write function requires an additional 4 ms to write the Black Box fault log into the NVM. The user must provide enough local capacitance to maintain the VDD rail above VSHDN for 500 µs (or 4.5 ms with the Black Box fault log) to preserve the first fault log. More capacitance allows more fault events to be written into the NVM during brownout.

UCD91320 Reset and Brownout ThresholdsFigure 6-1 Reset and Brownout Thresholds