SLUSDC1 September   2018 UCD90320U

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Simplified Application
  4. 4 Revision History
  5. 5 Description Continued
  6. 6 Pin Configuration and Functions
    1.     Pin 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 Non-Volatile Memory Characteristics
    7. 7.7 I2C/PMBus Interface Timing Requirements
    8. 7.8 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 TI Fusion Digital Power Designer software
      2. 8.3.2 PMBUS Interface
      3. 8.3.3 Rail Setup
    4. 8.4 Device Functional Modes
      1. 8.4.1  Rail Monitoring Configuration
      2. 8.4.2  GPI Configuration
      3. 8.4.3  Rail Sequence Configuration
      4. 8.4.4  Fault Responses Configuration
      5. 8.4.5  GPO Configuration
        1. 8.4.5.1 Command Controlled GPO
        2. 8.4.5.2 Logic GPO
      6. 8.4.6  Margining Configuration
      7. 8.4.7  Pin Selected Rail States Configuration
      8. 8.4.8  Watchdog Timer
      9. 8.4.9  System Reset Function
      10. 8.4.10 Cascading Multiple Devices
      11. 8.4.11 Rail Monitoring
      12. 8.4.12 Status Monitoring
      13. 8.4.13 Data and Error Logging to EEPROM Memory
      14. 8.4.14 Black Box First Fault Logging
      15. 8.4.15 PMBus Address Selection
      16. 8.4.16 ADC Reference
      17. 8.4.17 Device Reset
      18. 8.4.18 Brownout
      19. 8.4.19 Internal Fault Management
      20. 8.4.20 Single Event Upset
    5. 8.5 Device Configuration and Programming
  9. 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
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Community Resources
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.4.18 Brownout

The UCD90320U device triggers brownout event when the V33D pin voltage drops below the brownout threshold voltage, (VBOR). During a brownout event, the device continues to write fault logs into the EEPROM that occurred before the brownout event. As the supply voltage continues to drop, the device fully shuts down when the V33D pin voltage is below the shutdown threshold voltage (VSHDN). Any fault event that has not been written into the EEPROM before the device shutdown is lost.

In the scenario where several faults happen immediately before the brownout event, the device requires a capacitance of 500 µs in order to write the first fault event into the EEPROM. The write function requires an additional 4 ms to write the Black Box fault log into the EEPROM. Therefore, in order to preserve at least the first fault log, user must provide enough local capacitance to maintain the V33D rail above VSHDN for 500 µs (or 4.5ms with the Black Box fault log). Longer holdup time allows more fault events to be written into the EEPROM during brownout.

NOTE

The hold-up time is affected by V33D rail capacitance, the UCD90320U supply current and external circuits that source current from the rail (such as LEDs, load current on I/O pins, and other devices powered by the same rail).
UCD90320U reset_brownout_thresholds_slusch8.gifFigure 36. Reset and Brownout Thresholds