SLUS812D February   2008  – February 2020 TPS51200

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified DDR Application
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 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  Sink and Source Regulator (VO Pin)
      2. 7.3.2  Reference Input (REFIN Pin)
      3. 7.3.3  Reference Output (REFOUT Pin)
      4. 7.3.4  Soft-Start Sequencing
      5. 7.3.5  Enable Control (EN Pin)
      6. 7.3.6  Powergood Function (PGOOD Pin)
      7. 7.3.7  Current Protection (VO Pin)
      8. 7.3.8  UVLO Protection (VIN Pin)
      9. 7.3.9  Thermal Shutdown
      10. 7.3.10 Tracking Start-up and Shutdown
      11. 7.3.11 Output Tolerance Consideration for VTT DIMM Applications
      12. 7.3.12 REFOUT (VREF) Consideration for DDR2 Applications
    4. 7.4 Device Functional Modes
      1. 7.4.1 Low Input Voltage Applications
      2. 7.4.2 S3 and Pseudo-S5 Support
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input Voltage Capacitor
        2. 8.2.2.2 VLDO Input Capacitor
        3. 8.2.2.3 Output Capacitor
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
      1. 8.3.1 3.3-VIN, DDR2 Configuration
      2. 8.3.2 2.5-VIN, DDR3 Configuration
      3. 8.3.3 3.3-VIN, LP DDR3 or DDR4 Configuration
      4. 8.3.4 3.3-VIN, DDR3 Tracking Configuration
      5. 8.3.5 3.3-VIN, LDO Configuration
      6. 8.3.6 3.3-VIN, DDR3 Configuration with LFP
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Design Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Evaluation Modules
        2. 11.1.2.2 Spice Models
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

7.3.10 Tracking Start-up and Shutdown

The TPS51200 also supports tracking start-up and shutdown when the EN pin is tied directly to the system bus and not used to turn on or turn off the device. During tracking start-up, VO follows REFOUT once REFIN voltage is greater than 0.39 V. REFIN follows the rise of VDDQ rail through a voltage divider. The typical soft-start time (tSS) for the VDDQ rail is approximately 3 ms, however it may vary depending on the system configuration. The soft-start time of the VO output no longer depends on the OCL setting, but it is a function of the soft-start time of the VDDQ rail. PGOOD is asserted 2 ms after VVO is within ±20% of REFOUT. During tracking shutdown, the VO pin voltage falls following REFOUT until REFOUT reaches 0.37 V. When REFOUT falls below 0.37 V, the internal discharge MOSFETs turn on and quickly discharge both REFOUT and VO to GND. PGOOD is deasserted when VO is beyond the ±20% range of REFOUT. Figure 20 shows the typical timing diagram for an application that uses tracking start-up and shutdown.

TPS51200 v08021_lus812.gifFigure 19. Typical Timing Diagram for S3 and Pseudo-S5 Support
TPS51200 v08020_lus812.gifFigure 20. Typical Timing Diagram of Tracking Start-up and Shutdown