SLUS774C AUGUST   2007  – December 2014

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3  Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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  Voltage Reference
      2. 7.3.2  Oscillator
      3. 7.3.3  Input Undervoltage Lockout (UVLO) and Startup
      4. 7.3.4  Enable and Timed Turn On of the Outputs
      5. 7.3.5  Output Voltage Sequencing
      6. 7.3.6  Soft-Start
      7. 7.3.7  Output Voltage Regulation
      8. 7.3.8  Feedback Loop and Inductor-Capacitor (L-C) Filter Selection
      9. 7.3.9  Inductor-Capacitor (L-C) Selection
      10. 7.3.10 Maximum Output Capacitance
      11. 7.3.11 Minimum Output Capacitance
      12. 7.3.12 Modifying The Feedback Loop
        1. 7.3.12.1 Using High-ESR Output Capacitors
        2. 7.3.12.2 Using All Ceramic Output Capacitors
      13. 7.3.13 Example: TPS54386 Buck Converter Operating at 12-V Input, 3.3-V Output and 400-mA(P-P) Ripple Current
      14. 7.3.14 Bootstrap for the N-Channel MOSFET
      15. 7.3.15 Light Load Operation
      16. 7.3.16 SW Node Ringing
        1. 7.3.16.1 SW Node Snubber
        2. 7.3.16.2 Bootstrap Resistor
      17. 7.3.17 Output Overload Protection
      18. 7.3.18 Operating Near Maximum Duty Cycle
      19. 7.3.19 Dual Supply Operation
      20. 7.3.20 Cascading Supply Operation
      21. 7.3.21 Multiphase Operation
      22. 7.3.22 Bypass and FIltering
      23. 7.3.23 Overtemperature Protection and Junction Temperature Rise
      24. 7.3.24 Power Derating
    4. 7.4 Device Functional Modes
      1. 7.4.1 Minimum Input Voltage
      2. 7.4.2 ENx Control
  8. 8 Applications and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 12-V to 5-V and 3.3-V Converter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Duty Cycle Estimation
          2. 8.2.1.2.2  Inductor Selection
          3. 8.2.1.2.3  Rectifier Diode Selection
          4. 8.2.1.2.4  Output Capacitor Selection
          5. 8.2.1.2.5  Voltage Setting
          6. 8.2.1.2.6  Compensation Capacitors
          7. 8.2.1.2.7  Input Capacitor Selection
          8. 8.2.1.2.8  Boot Strap Capacitor
          9. 8.2.1.2.9  ILIM
          10. 8.2.1.2.10 SEQ
          11. 8.2.1.2.11 Power Dissipation
        3. 8.2.1.3 Application Curves
      2. 8.2.2 24-V to 12-V and 24-V to 5-V
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
      3. 8.2.3 5-V to 3.3V and 5-V to 1.2 V
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
        3. 8.2.3.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 PowerPAD Package
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Definition of Symbols
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

1 Features

  • 4.5-V to 28-V Input Range
  • Output Voltage Range 0.8 V to 90% of Input Voltage
  • Output Current Up to 3 A
  • Two Fixed Switching Frequency Versions:
    • TPS54383: 300 kHz
    • TPS54386: 600 kHz
  • Three Selectable Levels of Overcurrent Protection (Output 2)
  • 0.8-V 1.5% Voltage Reference
  • 2.1-ms Internal Soft-Start
  • Dual PWM Outputs 180° Out-of-Phase
  • Ratiometric or Sequential Startup Modes Selectable by a Single Pin
  • 85-mΩ Internal High-Side MOSFETs
  • Current Mode Control
  • Internal Compensation (See Page 16)
  • Pulse-by-Pulse Overcurrent Protection
  • Thermal Shutdown Protection at +148°C
  • 14-Pin PowerPAD™ HTSSOP package

2 Applications

  • Set Top Box
  • Digital TV
  • Power for DSP
  • Consumer Electronics

3 Description

The TPS54383 and TPS54386 are dual output, non-synchronous buck converters capable of supporting 3-A output applications that operate from a 4.5-V to 28-V input supply voltage, and require output voltages between 0.8 V and 90% of the input voltage.

With an internally-determined operating frequency, soft-start time, and control loop compensation, these converters provide many features with a minimum of external components. Channel 1 overcurrent protection is set at 4.5 A, while Channel 2 overcurrent protection level is selected by connecting a pin to ground, to BP, or left floating. The setting levels are used to allow for scaling of external components for applications that do not need the full load capability of both outputs.

The outputs may be enabled independently, or may be configured to allow either ratio-metric or sequential startup sequencing. Additionally, the two outputs may be powered from different sources.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
TPS54383 HTSSOP (14) 4.40 mm × 5.00 mm
TPS54386
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Simplified Schematic

v07123_lus774.gif

4 Revision History

Changes from B Revision (October 2007) to C Revision

  • Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section.Go