JAJSJN2D November   2007  – October 2020 TPS2041B-Q1 , TPS2042B-Q1 , TPS2051B-Q1

PRODUCTION DATA  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
  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 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagrams
    3. 8.3 Feature Description
      1. 8.3.1 Power Switch
      2. 8.3.2 Charge Pump
      3. 8.3.3 Driver
      4. 8.3.4 Enable ( ENx)
      5. 8.3.5 Enable (EN)
      6. 8.3.6 Overcurrent ( OCx)
      7. 8.3.7 Current Sense
      8. 8.3.8 Thermal Sense
      9. 8.3.9 Undervoltage Lockout (UVLO)
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Universal Serial Bus (USB) Applications
    2. 9.2 Typical Applications
      1. 9.2.1 TPS2042B-Q1 Typical Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Overcurrent
          2. 9.2.1.2.2 OC Response
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Hosts and Self-Powered Hubs and Bus-Powered Hubs
        1. 9.2.2.1 Design Requirements
          1. 9.2.2.1.1 USB Power-Distribution Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Low-Power Bus-Powered and High-Power Bus-Powered Functions
      3. 9.2.3 Generic Hot-Plug Applications
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Thermal Considerations
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 ドキュメントの更新通知を受け取る方法
    3. 12.3 サポート・リソース
    4. 12.4 Trademarks
    5. 12.5 静電気放電に関する注意事項
    6. 12.6 用語集
  13. 13Mechanical, Packaging, and Orderable Information

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

11.3 Thermal Considerations

The low on-resistance on the N-channel MOSFET allows the small surface-mount packages to pass large currents. The thermal resistances of these packages are high compared to those of power packages; it is good design practice to check power dissipation and junction temperature. Begin by determining the rDS(ON) of the N-channel MOSFET relative to the input voltage and operating temperature. As an initial estimate, use the highest operating ambient temperature of interest and read rDS(ON) from GUID-0FF1847F-B01B-41B3-9A8D-D42D66B7DAEC.html#SLVS782FIG5883. Using this value, the power dissipation per switch can be calculated by #SLVS7821040:

Equation 1. PD = rDS(ON) × I2

Multiply this number by the number of switches being used. This step renders the total power dissipation from the N-channel MOSFETs.

Finally, calculate the junction temperature with #SLVS7826602:

Equation 2. TJ = PD × RθJA + TA

where

  • TA = Ambient temperature °C
  • RθJA = Thermal resistance
  • PD = Total power dissipation based on number of switches being used.

Compare the calculated junction temperature with the initial estimate. If they do not agree within a few degrees, repeat the calculation, using the calculated value as the new estimate. Two or three iterations are generally sufficient to get a reasonable answer.