JAJSVO7 November   2024 TPS923650

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Adaptive Off-Time Current Mode Control
      2. 7.3.2 Setting LED Current
      3. 7.3.3 Internal Soft Start
      4. 7.3.4 Dimming Mode
        1. 7.3.4.1 PWM Dimming
        2. 7.3.4.2 Analog Dimming
      5. 7.3.5 Fault Protection
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 TPS923651D2 12V Input, 1A Output, 8-piece WLED Driver With Analog Dimming
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selection
          2. 8.2.1.2.2 Input Capacitor Selection
          3. 8.2.1.2.3 Output Capacitor Selection
          4. 8.2.1.2.4 Sense Resistor Selection
          5. 8.2.1.2.5 Other External Components Selection
        3. 8.2.1.3 Application Curves
      2. 8.2.2 TPS923650D1 Buck-Boost, 24V Input, 0.5A Output, 4-piece WLED Driver with PWM Dimming
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Inductor Selection
          2. 8.2.2.2.2 Input Capacitor Selection
          3. 8.2.2.2.3 Output Capacitor Selection
          4. 8.2.2.2.4 Sense Resistor Selection
          5. 8.2.2.2.5 Other External Components Selection
        3. 8.2.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 ドキュメントの更新通知を受け取る方法
    2. 9.2 サポート・リソース
    3. 9.3 Trademarks
    4. 9.4 静電気放電に関する注意事項
    5. 9.5 用語集
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Package Option Addendum
    2. 11.2 Tape and Reel Information
8.2.2.2.2 Input Capacitor Selection

An input capacitor is required to reduce the surge current drawn from the input supply and the switching noise coming from the device. Electrolytic capacitors are recommended for energy storage. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For most applications, it is recommended to place a 10μF capacitor along with a 0.1µF capacitor from VIN to GND to provide high-frequency filtering. The input capacitor voltage rating must be greater than the maximum input voltage. Use the equation below to calculate the input ripple voltage, where ESRCIN is the ESR of input capacitor, and KDR is the derating coefficient of ceramic capacitance at the applied DC voltage.

Equation 16. V I N ( r i p p l e ) = I L ( m a x ) 2 π × f P W M × C O U T

In this design, a 10µF, 50V electrolytic capacitor, a 22µF, 50V X7R ceramic capacitor and a 0.1µF, 50V X7R ceramic capacitor are chosen, yielding around 270mV input ripple voltage.