JAJSRB5A September   2023  – November 2023 TPS7B4256-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 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Tracker Output Voltage (VOUT)
        1. 6.3.1.1 Output Voltage Equal to Reference Voltage
        2. 6.3.1.2 Output Voltage Less Than the Reference Voltage
        3. 6.3.1.3 Output Voltage Larger Than the Reference Voltage
      2. 6.3.2 Reverse Current Protection
      3. 6.3.3 Undervoltage Lockout
      4. 6.3.4 Thermal Protection
      5. 6.3.5 Current Limit
      6. 6.3.6 Output Short to Battery
      7. 6.3.7 Tracking Regulator With an Enable Circuit
    4. 6.4 Device Functional Modes
      1. 6.4.1 Normal Operation
      2. 6.4.2 Dropout Operation
      3. 6.4.3 Operation With VIN < 3 V
      4. 6.4.4 Disable With ADJ/EN Control
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Dropout Voltage
      2. 7.1.2 Reverse Current
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Input and Output Capacitor Selection
        2. 7.2.2.2 Feedback Resistor Selection
        3. 7.2.2.3 Feedforward Capacitor
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
        1. 7.4.1.1 Package Mounting
        2. 7.4.1.2 Board Layout Recommendations to Improve PSRR and Noise Performance
        3. 7.4.1.3 Power Dissipation and Thermal Considerations
        4. 7.4.1.4 Thermal Performance Versus Copper Area
        5. 7.4.1.5 Layout Examples
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Device Nomenclature
    2. 8.2 ドキュメントの更新通知を受け取る方法
    3. 8.3 サポート・リソース
    4. 8.4 Trademarks
    5. 8.5 静電気放電に関する注意事項
    6. 8.6 用語集
  10. 9 Revision History
  11. 10Mechanical, 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

7.4.1.3 Power Dissipation and Thermal Considerations

Equation 11 calculates the device power dissipation.

Equation 11. 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 11 can be ignored.

Calculate the junction temperature (TJ) with Equation 12 for a device under operation at a given ambient air temperature (TA).

Equation 12. TJ = TA + (RθJA × PD)

where:

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

Equation 13 calculates a rise in junction temperature because of power dissipation.

Equation 13. ΔT = TJ – TA = (RθJA × PD)

The maximum ambient air temperature (TAMAX) at which the device can operate can be calculated with Equation 14 for a given maximum junction temperature (TJMAX).

Equation 14. TAMAX = TJMAX – (RθJA × PD)