SLVSCD5D November   2014  – February 2016 TPS54335-1A , TPS54335A , TPS54336A

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 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 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  Fixed-Frequency PWM Control
      2. 7.3.2  Light-Load Operation
      3. 7.3.3  Voltage Reference
      4. 7.3.4  Adjusting the Output Voltage
      5. 7.3.5  Enabling and Adjusting Undervoltage Lockout
      6. 7.3.6  Error Amplifier
      7. 7.3.7  Slope Compensation and Output Current
      8. 7.3.8  Safe Startup into Pre-Biased Outputs
      9. 7.3.9  Bootstrap Voltage (BOOT)
      10. 7.3.10 Adjustable Switching Frequency (TPS54335A Only)
      11. 7.3.11 Soft-Start (TPS54336A Only)
      12. 7.3.12 Output Overvoltage Protection (OVP)
      13. 7.3.13 Overcurrent Protection
        1. 7.3.13.1 High-Side MOSFET Overcurrent Protection
        2. 7.3.13.2 Low-Side MOSFET Overcurrent Protection
      14. 7.3.14 Thermal Shutdown
      15. 7.3.15 Small-Signal Model for Loop Response
      16. 7.3.16 Simple Small-Signal Model for Peak Current-Mode Control
      17. 7.3.17 Small-Signal Model for Frequency Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Operation With VI < 4.5 V (minimum VI)
      2. 7.4.2 Operation With EN Control
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Supplementary Guidance
      2. 8.1.2 Differences Between the Two DRC Packages
    2. 8.2 Typical Applications
      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 Switching Frequency
        3. 8.2.2.3 Output Voltage Set Point
        4. 8.2.2.4 Undervoltage Lockout Set Point
        5. 8.2.2.5 Input Capacitors
        6. 8.2.2.6 Output Filter Components
          1. 8.2.2.6.1 Inductor Selection
          2. 8.2.2.6.2 Capacitor Selection
        7. 8.2.2.7 Compensation Components
        8. 8.2.2.8 Bootstrap Capacitor
        9. 8.2.2.9 Power Dissipation Estimate
      3. 8.2.3 Application Curves
      4. 8.2.4 TPS54336A Typical Application
        1. 8.2.4.1 Design Requirements
        2. 8.2.4.2 Detailed Design Procedure
          1. 8.2.4.2.1 TPS54336A Design
          2. 8.2.4.2.2 Soft-Start Capacitor
        3. 8.2.4.3 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 Custom Design with WEBENCH Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Device Support
      1. 11.3.1 Development Support
    4. 11.4 Documentation Support
      1. 11.4.1 Related Documentation
    5. 11.5 Related Links
    6. 11.6 Community Resource
    7. 11.7 Trademarks
    8. 11.8 Electrostatic Discharge Caution
    9. 11.9 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • DRC|10
  • DDA|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

10 Layout

10.1 Layout Guidelines

The VIN pin should be bypassed to ground with a low-ESR ceramic bypass capacitor. Care should be taken to minimize the loop area formed by the bypass capacitor connection, the VIN pin, and the GND pin of the IC. The typical recommended bypass capacitance is 10-μF ceramic with a X5R or X7R dielectric and the optimum placement is closest to the VIN and GND pins of the device. See Figure 55 for a PCB layout example. The GND pin should be tied to the PCB ground plane at the pin of the IC. To facilitate close placement of the input bypass capacitors, the PH pin should be routed to a small copper area directly adjacent to the pin. Use vias to route the PH signal to the bottom side or an inner layer. If necessary, allow the top-side copper area to extend slightly under the body of the closest input bypass capacitor. Make the copper trace on the bottom or internal layer short and wide as practical to reduce EMI issues. Connect the trace with vias back to the top side to connect with the output inductor as shown after the GND pin. In the same way use a bottom or internal layer trace to route the PH signal across the VIN pin to connect to the boot capacitor as shown. Make the circulating loop from the PH pin to the output inductor and output capacitors and then back to GND as tight as possible while preserving adequate etch width to reduce conduction losses in the copper . For operation at a full rated load, the ground area near the IC must provide adequate heat dissipating area. Connect the exposed thermal pad to the bottom or internal layer ground plane using vias as shown. Additional vias may be used adjacent to the IC to tie top-side copper to the internal or bottom layer copper. The additional external components can be placed approximately as shown. Use a separate ground trace to connect the feedback, compensation, UVLO, and RT (SS for TPS54336A) returns. Connect this ground trace to the main power ground at a single point to minimize circulating currents. Obtaining acceptable performance with alternate layout schemes is possible; however this layout has been shown to produce good results and is intended as a guideline.

10.2 Layout Example

TPS54335A TPS54335-1A TPS54336A layout_slvsc03.gif

NOTE:

Pin 8 for the TPS54336A device is SS. Connect an SS capacitor instead of an RT resistor from pin 8 to GND.
Figure 55. TPS54335ADDA Board Layout