JAJS448D March   2010  – October 2018 TPS54260

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      概略回路図
      2.      効率と負荷電流との関係
  4. 4 改訂履歴
  5. 5 概要（続き）
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Fixed Frequency PWM Control
      2. 8.3.2  Slope Compensation Output Current
      3. 8.3.3  Pulse-Skip Eco-Mode
      4. 8.3.4  Low-Dropout Operation and Bootstrap Voltage (BOOT)
      5. 8.3.5  Error Amplifier
      6. 8.3.6  Voltage Reference
      7. 8.3.7  Adjusting the Output Voltage
      8. 8.3.8  Enable and Adjusting Undervoltage Lockout
      9. 8.3.9  Slow-Start / Tracking Pin (SS/TR)
      10. 8.3.10 Overload Recovery Circuit
      11. 8.3.11 Sequencing
      12. 8.3.12 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)
      13. 8.3.13 Overcurrent Protection and Frequency Shift
      14. 8.3.14 Selecting the Switching Frequency
      15. 8.3.15 How to Interface to RT/CLK Pin
      16. 8.3.16 Powergood (PWRGD Pin)
      17. 8.3.17 Overvoltage Transient Protection
      18. 8.3.18 Thermal Shutdown
      19. 8.3.19 Small Signal Model for Loop Response
      20. 8.3.20 Simple Small Signal Model for Peak Current Mode Control
      21. 8.3.21 Small Signal Model for Frequency Compensation
    4. 8.4 Device Functional Modes
      1. 8.4.1 Operation Near Minimum Input Voltage
      2. 8.4.2 Operation With Enable Control
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 3.3-V Output Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1  Custom Design With WEBENCH® Tools
          2. 9.2.1.2.2  Selecting the Switching Frequency
          3. 9.2.1.2.3  Output Inductor Selection (LO)
          4. 9.2.1.2.4  Output Capacitor
          5. 9.2.1.2.5  Catch Diode
          6. 9.2.1.2.6  Input Capacitor
          7. 9.2.1.2.7  Slow-Start Capacitor
          8. 9.2.1.2.8  Bootstrap Capacitor Selection
          9. 9.2.1.2.9  Undervoltage Lock Out Set Point
          10. 9.2.1.2.10 Output Voltage and Feedback Resistors Selection
          11. 9.2.1.2.11 Compensation
          12. 9.2.1.2.12 Discontinuous Mode and Eco-Mode Boundary
          13. 9.2.1.2.13 Power Dissipation Estimate
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Inverting Power Supply
      3. 9.2.3 Split-Rail Power Supply
      4. 9.2.4 12-V to 3.8-V GSM Power Supply
      5. 9.2.5 24-V to 4.2-V GSM Power Supply
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 デバイス・サポート
      1. 12.1.1 デベロッパー・ネットワークの製品に関する免責事項
      2. 12.1.2 開発サポート
        1. 12.1.2.1 WEBENCH®ツールによるカスタム設計
    2. 12.2 ドキュメントの更新通知を受け取る方法
    3. 12.3 コミュニティ・リソース
    4. 12.4 商標
    5. 12.5 静電気放電に関する注意事項
    6. 12.6 Glossary
  13. 13メカニカル、パッケージ、および注文情報

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

8.3.12 Constant Switching Frequency and Timing Resistor (RT/CLK Pin)

The switching frequency of the TPS54260 is adjustable over a wide range from approximately 100 kHz to 2500 kHz by placing a resistor on the RT/CLK pin. The RT/CLK pin voltage is typically 0.5 V and must have a resistor-to-ground to set the switching frequency. To determine the timing resistance for a given switching frequency, use Equation 11 or the curves in Figure 39 or Figure 40. To reduce the solution size one would typically set the switching frequency as high as possible, but tradeoffs of the supply efficiency, maximum input voltage and minimum controllable on time should be considered.

The minimum controllable on time is typically 135 ns and limits the maximum operating input voltage.

The maximum switching frequency is also limited by the frequency shift circuit. More discussion on the details of the maximum switching frequency is located below.

Equation 11. TPS54260 eq11_lvs795.gif
TPS54260 fs_clk_res_lvs795.gifFigure 39. Switching Frequency vs RT/CLK Resistance High-Frequency Range
TPS54260 C006_SLVS919.gifFigure 40. Switching Frequency vs RT/CLK Resistance Low-Frequency Range