SLVSBF0C JULY   2012  – April 2019 TPS53015

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified 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 Drivers
      2. 7.3.2 5-Volt Regulator
      3. 7.3.3 Soft-Start and Pre-biased Soft-Start Time
      4. 7.3.4 Overcurrent Protection
      5. 7.3.5 Overvoltage and Undervoltage Protection
      6. 7.3.6 UVLO Protection
      7. 7.3.7 Thermal Shutdown
      8. 7.3.8 Power Good
    4. 7.4 Device Functional Modes
      1. 7.4.1 PWM Operation
      2. 7.4.2 Auto-skip Eco-Mode Control
  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 Determine the Inductance Value
        2. 8.2.2.2 Output Capacitor
        3. 8.2.2.3 Input Capacitor
        4. 8.2.2.4 Bootstrap Capacitor
        5. 8.2.2.5 VREG5 Capacitor
        6. 8.2.2.6 Choose Output Voltage Resistors
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Trademarks
    2. 11.2 Electrostatic Discharge Caution
    3. 11.3 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.3 Soft-Start and Pre-biased Soft-Start Time

The TPS53015 operates with an internally set, 1.4-ms soft-start time. When the EN pin becomes high and the VREG5 voltage is above the UVLO threshold, an internal DAC ramps up the reference voltage to the PWM comparator. Smooth control of the output voltage is maintained during start up.

The device contains a unique circuit to prevent current from being pulled from the output during startup if the output is pre-biased. When the soft-start commands a voltage higher than the pre-bias level (internal soft-start time becomes greater than internal feedback voltage VFB), the controller slowly activates synchronous rectification by starting the first low side FET gate driver pulses with a narrow on-time. It then increments that on-time on a cycle-by-cycle basis until it coincides with the time dictated by (1-D), where D is the duty cycle of the converter. This scheme prevents the initial sinking of the pre-biased output, and ensures that the output voltage (VOUT) starts and ramps up smoothly into regulation from pre-biased startup to normal mode operation.