SLVSFQ0B October   2020  – June 2024 TPS54J061

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 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Enable and Internal LDO
      2. 6.3.2  Split Rail and External LDO
      3. 6.3.3  Output Voltage Setting
      4. 6.3.4  Soft Start and Output-Voltage Tracking
      5. 6.3.5  Frequency and Operation Mode Selection
      6. 6.3.6  D-CAP3™ Control Mode
      7. 6.3.7  Current Sense and Positive Overcurrent Protection
      8. 6.3.8  Low-side FET Negative Current Limit
      9. 6.3.9  Power Good
      10. 6.3.10 Overvoltage and Undervoltage Protection
      11. 6.3.11 Out-Of-Bounds Operation (OOB)
      12. 6.3.12 Output Voltage Discharge
      13. 6.3.13 UVLO Protection
      14. 6.3.14 Thermal Shutdown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Auto-Skip Eco-Mode Light Load Operation
      2. 6.4.2 Forced Continuous-Conduction Mode
      3. 6.4.3 Pre-Bias Start-up
  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
        1. 7.2.2.1  Choose the Switching Frequency and Operation Mode (MODE Pin)
        2. 7.2.2.2  Choose the Output Inductor (L)
        3. 7.2.2.3  Set the Current Limit (TRIP)
        4. 7.2.2.4  Choose the Output Capacitors (COUT)
        5. 7.2.2.5  Choose the Input Capacitors (CIN)
        6. 7.2.2.6  Feedback Network (FB Pin)
        7. 7.2.2.7  Soft Start Capacitor (SS/REFIN Pin)
        8. 7.2.2.8  EN Pin Resistor Divider
        9. 7.2.2.9  VCC Bypass Capacitor
        10. 7.2.2.10 BOOT Capacitor
        11. 7.2.2.11 Series BOOT Resistor and RC Snubber
        12. 7.2.2.12 PGOOD Pullup Resistor
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Documentation Support
      1. 8.1.1 Related Documentation
    2. 8.2 Support Resources
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Trademarks
    5. 8.5 Glossary
    6. 8.6 Electrostatic Discharge Caution
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Ordering Information

6.4.1 Auto-Skip Eco-Mode Light Load Operation

While the MODE pin is pulled to VCC directly or connected to AGND pin through a resistor larger than 121 kΩ, the device automatically reduces the switching frequency at light-load conditions to maintain high efficiency. This section describes the operation in detail.

As the output current decreases from heavy load condition, the inductor current also decreases until the rippled valley of the inductor current touches IZC, the zero-cross detection current threshold. IZC is the boundary between the continuous-conduction and discontinuous-conduction modes. The synchronous MOSFET turns off when this zero inductor current is detected. As the load current decreases further, the converter runs into discontinuous-conduction mode (DCM). After 16 consecutive detections of zero crossings, the TPS54J061 enters Eco-Mode and the switching frequency begins to decrease. The on-time is maintained to a level approximately the same as during continuous-conduction mode operation so that discharging the output capacitor with a smaller load current to the level of the reference voltage requires more time. The transition point to the light-load operation IOUT(LL) (for example, the threshold between continuous- and discontinuous-conduction mode) is calculated as shown in Equation 5.

Equation 5. TPS54J061

where

  • fSW is the PWM switching frequency

Only using ceramic capacitors is recommended for auto-skip mode.