SLVSEJ2A February   2018  – April 2018 TPSM84424

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Transient Response
  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 Switching Characteristics
    7. 6.7 Typical Characteristics (VIN = 12 V)
    8. 6.8 Typical Characteristics (VIN = 5 V)
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Adjusting the Output Voltage
      2. 7.3.2  Switching Frequency (RT)
      3. 7.3.3  Synchronization (CLK)
      4. 7.3.4  Output On/Off Enable (EN)
      5. 7.3.5  Input Capacitor Selection
      6. 7.3.6  Output Capacitor Selection
      7. 7.3.7  TurboTrans (TT)
        1. 7.3.7.1 Low-ESR Output Capacitors
        2. 7.3.7.2 Transient Response
          1. 7.3.7.2.1 Transient Waveforms (VIN = 12 V)
      8. 7.3.8  Undervoltage Lockout (UVLO)
      9. 7.3.9  Soft Start (SS/TR)
      10. 7.3.10 Sequencing (SS/TR)
      11. 7.3.11 Power Good (PGOOD)
      12. 7.3.12 Safe Start-up into Pre-Biased Outputs
      13. 7.3.13 Overcurrent Protection
      14. 7.3.14 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Shutdown Mode
  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 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Output Voltage Setpoint
        3. 8.2.2.3 Setting the Switching Frequency
        4. 8.2.2.4 Input Capacitors
        5. 8.2.2.5 Output Capacitors
        6. 8.2.2.6 TurboTrans Resistor
        7. 8.2.2.7 Application Waveforms
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
    3. 10.3 EMI
      1. 10.3.1 EMI Plots
    4. 10.4 Package Specifications
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Development Support
      1. 11.2.1 Custom Design With WEBENCH® Tools
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Tape and Reel Information

7.3.7 TurboTrans (TT)

The TPSM84424 includes the TurboTrans feature which optimizes the transient response of the converter while simultaneously reducing the quantity of external output capacitors required to meet a target voltage deviation specification. A TurboTrans resistor, RTT, is required between the TT pin and AGND to properly set the response of the TPSM84424 based on the amount and type of output capacitors. The value of RTT can be calculated using Equation 3. In order to calculate the RTT value, a TurboTrans constant, KTT, is required. See Table 5 for the KTT value when using only ceramic output capacitors. See Table 6 for the KTT value when using a combination of ceramic and polymer output capacitors. Applications operating from input voltages above 14 V, must reduce the calculated RTT value by 20%. Also, the value of CO used in Equation 3 is the total effective output capacitance, which takes into account the effects of applied voltage and temperature.

Equation 3. TPSM84424 RttEq2.gif

Table 5. KTT Values (Ceramic Only Output Capacitors)

VOUT (V) 1 - < 1.2 1.2 - < 1.5 1.5 - < 1.8 1.8 - < 2 2 - < 2.5 2.5 - < 3.3 3.3 - < 7.5 7.5 - 10
KTT 1 1.12 1.4 1.5 1.65 1.8 2.0 2.25

Table 6. KTT Values (Ceramic + Polymer Output Capacitors)

VOUT (V) 0.6 - < 0.7 0.7 - < 0.9 0.9 - < 1 1 - < 2.5 2.5 - < 3.3 3.3 - < 5 5 - < 6 6 - < 7.5 7.5 - 10
KTT 0.6 0.65 0.7 0.6 0.72 0.9 1.2 1.5 1.8