SLVS400D August   2001  – January 2015 TPS54611 , TPS54612 , TPS54613 , TPS54614 , TPS54615 , TPS54616

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 Recommended Operating Conditions
    3. 6.3 Thermal Information
    4. 6.4 Dissipation Ratings
    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  Undervoltage Lock Out (UVLO)
      2. 7.3.2  Slow-Start and Enable (SS/ENA)
      3. 7.3.3  VBIAS Regulator
      4. 7.3.4  Voltage Reference
      5. 7.3.5  Oscillator and PWM Ramp
      6. 7.3.6  Error Amplifier
      7. 7.3.7  PWM Control
      8. 7.3.8  Dead-Time Control and MOSFET Drivers
      9. 7.3.9  Overcurrent Protection
      10. 7.3.10 Thermal Shutdown
      11. 7.3.11 Powergood (PWRGD)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Continuous Conduction 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 Component Selection
        2. 8.2.2.2 Input Filter
        3. 8.2.2.3 Feedback Circuit
        4. 8.2.2.4 Operating Frequency
        5. 8.2.2.5 Output Filter
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Related DC - DC Products
    2. 11.2 Related Links
    3. 11.3 Trademarks
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Application Information

The TPS5461x devices are fixed output voltage synchronous step-down DC-DC converters. These devices are used to convert a higher DC input voltage to a lower DC output voltage with a maximum output current of 6A.

8.2 Typical Application

Figure 10 shows the schematic diagram for a typical TPS54614 application. The TPS54614 (U1) can provide greater than 6 A of output current at a nominal output voltage of 1.8 V. For proper operation, the exposed thermal PowerPAD underneath the integrated circuit package needs to be soldered to the printed-circuit board.

Application_Circuit_SLVS400C.gifFigure 10. Application Circuit

8.2.1 Design Requirements

The design requirements for this example are listed in Table 3.

Table 3. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE
DC Input Voltage Range 3 V – 6 V
DC Output Voltage 1 V
DC Output Current Range 0A – 6 A
Load Transient Step 3A – 6 A
Load Regulation Control ± 5 mV
Loop Crossover Frequency 50 kHz
Control Loop Phase Margin 55°

8.2.2 Detailed Design Procedure

8.2.2.1 Component Selection

The values for the components used in this design example were selected using the SWIFT designer software tool. SWIFT designer provides a complete design environment for developing dc-dc converters using the TPS54614, or other devices in the SWIFT product family. Additional design information is available at www.ti.com.

8.2.2.2 Input Filter

The input to the circuit is a nominal 3.3 VDC or 5 VDC. The input filter is a 220-μF POSCAP capacitor, with a maximum allowable ripple current of 3 A. A 10-µF ceramic capacitor for the TPS54614 is required, and must be located as close as possible to the device.

8.2.2.3 Feedback Circuit

The output voltage of the converter is fed directly into the VSENSE pin of the TPS54614. The TPS54614 is internally compensated to provide stability of the output under varying line and load conditions.

8.2.2.4 Operating Frequency

In the application circuit, 350 kHz operation is selected by leaving FSEL open. Different operating frequencies can be selected by connecting a resistor between RT pin and AGND. Choose the value of R using Equation 4 for the desired operating frequency:

Equation 4. Eq04_R_slvs400.gif

Alternately, a preset operating frequency of 550 kHz can be selected by leaving RT open and connecting the FSEL pin to VI.

8.2.2.5 Output Filter

The output filter is composed of a 5.2-µH inductor and a 470-µF capacitor. The inductor is low dc resistance (16-mΩ) type, Sumida CDRH104R−5R2. The capacitor used is a 4-V POSCAP with a maximum ESR of 40 mΩ. The output filter components work with the internal compensation network to provide a stable closed loop response for the converter.

8.2.3 Application Curves

Graph_10_SLVS400C.gifFigure 11. Efficiency vs Load Current
Graph_12_SLVS400C.gifFigure 13. Loop Response
Graph_14_SLVS400C.gifFigure 15. Start-up Waveforms
Graph_16_SLVS400C.gifFigure 17. Ambient Temperature vs Load Current
Graph_11_SLVS400C.gifFigure 12. Output Voltage vs Load Current
Graph_13_SLVS400C.gifFigure 14. Transient Response
Graph_15_SLVS400C.gifFigure 16. Output Ripple Voltage