JAJSN03A june   2022  – august 2023 TPS7B4255-Q1

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Revision History
  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 Timing Characteristics
    7. 6.7 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 Tracker Output Voltage (VOUT)
        1. 7.3.1.1 Output Voltage Equal to the Reference Voltage
        2. 7.3.1.2 Output Voltage Less Than the Reference Voltage
      2. 7.3.2 Reverse Current Protection
      3. 7.3.3 Undervoltage Lockout
      4. 7.3.4 Thermal Protection
      5. 7.3.5 Current Limit
      6. 7.3.6 Output Short to Battery
      7. 7.3.7 Tracking Regulator With an Enable Circuit
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Dropout Operation
      3. 7.4.3 Operation With VIN < 3 V
      4. 7.4.4 Disable With ADJ/EN Control
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Dropout Voltage
      2. 8.1.2 Reverse Current
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input and Output Capacitor Selection
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Package Mounting
        2. 8.4.1.2 Board Layout Recommendations to Improve PSRR and Noise Performance
        3. 8.4.1.3 Power Dissipation and Thermal Considerations
        4. 8.4.1.4 Thermal Performance Versus Copper Area
      2. 8.4.2 Layout Examples
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Device Nomenclature
    2. 9.2 ドキュメントの更新通知を受け取る方法
    3. 9.3 サポート・リソース
    4. 9.4 Trademarks
    5. 9.5 静電気放電に関する注意事項
    6. 9.6 用語集
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Mechanical Data

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

8.4.1.3 Power Dissipation and Thermal Considerations

Equation 4 calculates the device power dissipation.

Equation 4. PD = IOUT × (VIN – VOUT) + IQ × VIN

where:

  • PD = Continuous power dissipation
  • IOUT = Output current
  • VIN = Input voltage
  • VOUT = Output voltage
  • IQ = Quiescent current

Because IQ is much less than IOUT, the term IQ × VIN in Equation 4 can be ignored.

Calculate the junction temperature (TJ) with Equation 5 for a device under operation at a given ambient air temperature (TA).

Equation 5. TJ = TA + (RθJA × PD)

where:

  • RθJA = Junction-to-junction-ambient air thermal impedance

Equation 6 calculates a rise in junction temperature because of power dissipation.

Equation 6. ΔT = TJ – TA = (RθJA × PD)

The maximum ambient air temperature (TAMAX) at which the device can operate can be calculated with Equation 7 for a given maximum junction temperature (TJMAX).

Equation 7. TAMAX = TJMAX – (RθJA × PD)