ZHCSMB6E March   2010  – October 2020 TPS62065 , TPS62067

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and 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 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 Mode Selection (TPS62065)
      2. 8.3.2 Power Good Output (TPS62067)
      3. 8.3.3 Enable
      4. 8.3.4 Clock Dithering
      5. 8.3.5 Undervoltage Lockout
      6. 8.3.6 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Soft Start
      2. 8.4.2 Power Save Mode
      3. 8.4.3 Dynamic Voltage Positioning
      4. 8.4.4 100% Duty Cycle Low Dropout Operation
      5. 8.4.5 Internal Current Limit and Fold-Back Current Limit for Short Circuit Protection
      6. 8.4.6 Output Capacitor Discharge
  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
        1. 9.2.2.1 Output Voltage Setting
        2. 9.2.2.2 Output Filter Design (Inductor and Output Capacitor)
          1. 9.2.2.2.1 Inductor Selection
          2. 9.2.2.2.2 Output Capacitor Selection
          3. 9.2.2.2.3 Input Capacitor Selection
        3. 9.2.2.3 Checking Loop Stability
      3. 9.2.3 Application Curves
    3. 9.3 System Example
      1. 9.3.1 TPS62067 Adjustable 1.8-V Output
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Related Links
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

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8.4.2 Power Save Mode

At TPS62065 pulling the MODE pin low enables power save mode. In TPS62067 power save mode is enabled per default. If the load current decreases, the converter enters power save mode operation automatically. During power save mode the converter skips switching and operates with reduced frequency in PFM mode with a minimum quiescent current to maintain high efficiency. The converter positions the output voltage typically +1% above the nominal output voltage. This voltage positioning feature minimizes voltage drops caused by a sudden load step.

The transition from PWM mode to PFM mode occurs once the inductor current in the low-side MOSFET switch becomes zero, which indicates discontinuous conduction mode.

During the power save mode the output voltage is monitored with a PFM comparator. As the output voltage falls below the PFM comparator threshold of VOUTnominal +1%, the device starts a PFM current pulse. For this the high-side MOSFET switch will turn on and the inductor current ramps up. After the on-time expires the switch will be turned off and the low-side MOSFET switch will be turned on until the inductor current becomes zero.

The converter effectively delivers a current to the output capacitor and the load. If the load is below the delivered current the output voltage will rise. If the output voltage is equal or higher than the PFM comparator threshold, the device stops switching and enters a sleep mode with typically 18 µA current consumption.

In case the output voltage is still below the PFM comparator threshold, further PFM current pulses will be generated until the PFM comparator threshold is reached. The converter starts switching again once the output voltage drops below the PFM comparator threshold due to the load current.

The PFM mode is exited and PWM mode entered in case the output current can no longer be supported in PFM mode.