SLVSCG3F January   2014  – July 2017 TPS22968

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Schematic
  4. 4 Revision History
  5. 5 Device Comparison
  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 (VBIAS = 5 V)
    6. 7.6 Electrical Characteristics (VBIAS = 2.5 V)
    7. 7.7 Switching Characteristics
    8. 7.8 Typical DC Characteristics
    9. 7.9 Typical AC Characteristics
  8. 8 Parameter Measurement Information
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 ON and OFF Control
      2. 9.3.2 Input Capacitor (Optional)
      3. 9.3.3 Output Capacitor (Optional)
      4. 9.3.4 QOD (Optional)
      5. 9.3.5 VIN and VBIAS Voltage Range
      6. 9.3.6 Adjustable Rise Time
    4. 9.4 Device Functional Modes
  10. 10Application and Implementation
    1. 10.1 Application Information
      1. 10.1.1 Parallel Configuration
      2. 10.1.2 Standby Power Reduction
      3. 10.1.3 Power Supply Sequencing Without a GPIO Input
      4. 10.1.4 Reverse Current Blocking
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 VIN to VOUT Voltage Drop
        2. 10.2.2.2 Inrush Current
        3. 10.2.2.3 Thermal Considerations
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
    2. 12.2 Layout Example
  13. 13Device and Documentation Support
    1. 13.1 Device Support
      1. 13.1.1 Development Support
    2. 13.2 Documentation Support
      1. 13.2.1 Related Documentation
    3. 13.3 Related Links
    4. 13.4 Receiving Notification of Documentation Updates
    5. 13.5 Community Resources
    6. 13.6 Trademarks
    7. 13.7 Electrostatic Discharge Caution
    8. 13.8 Glossary
  14. 14Mechanical, 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

10.2.2.3 Thermal Considerations

The maximum IC junction temperature must be restricted to 125°C under normal operating conditions. To calculate the maximum allowable dissipation, PD(max) for a given output current and ambient temperature, use Equation 6.

Equation 6. TPS22968 TPS22968N eq_thrm_slvsci4.gif

where

  • PD(max) is the maximum allowable power dissipation
  • TJ(max) is the maximum allowable junction temperature (125°C for the TPS22968)
  • TA is the ambient temperature of the device
  • RθJA is the junction to air thermal impedance. See theThermal Information table. This parameter is highly dependent upon board layout.

Equation 7 to Equation 10 and Equation 11 to Equation 13 show two examples to determine how to use this information correctly:

For VBIAS = 5 V, VIN = 5 V, the maximum ambient temperature with a 4-A load through each channel can be determined by using Equation 7 to Equation 10:

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Equation 7. PD = I2 × R × 2 (multiplied by 2 because there are two channels)

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Equation 8. TPS22968 TPS22968N temp_eq1b_lvscg3.gif

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Equation 9. TA = TJ(MAX) – RθJA × 2 × I2 × R

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Equation 10. TA = 125°C – 62.5°C/W × 2 × (4 A)2 × 27 mΩ = 71°C

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For VBIAS = 5 V, VIN = 5 V, the maximum continuous current for an ambient temperature of 85°C with the same current flowing through each channel can be determined by using Equation 11 to Equation 13:

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Equation 11. TPS22968 TPS22968N temp_eq2a_lvscg3.gif

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Equation 12. TPS22968 TPS22968N temp_eq2b_lvscg3.gif

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Equation 13. TPS22968 TPS22968N temp_eq2c_lvscg3.gif