SLVS788D February   2009  – November 2016 TPS22951

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configurations 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 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Current Limit
      2. 8.3.2 Power Good Indication
      3. 8.3.3 EN and DET inputs
      4. 8.3.4 Thermal Shutdown
    4. 8.4 Device Functional Modes
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  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 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Community Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  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 Layout

11.1 Layout Guidelines

  • The VCC and PWR traces must be wide enough to carry the necessary load current (up to 600 mA).
  • To handle transient load currents, a capacitor may be placed close to the VCC pin.
  • To make use of the PG signal, it must be connected to a pullup resistor. The pullup source may be the VCC node. It is also possible to use a different source for the pullup resistor.

11.2 Layout Example

TPS22951 SLVS788-2_PG.gif Figure 14. Layout Example

11.3 Thermal Considerations

The maximum IC junction temperature must be restricted to 85°C under normal operating conditions. To calculate the maximum allowable dissipation, PD(max) for a given ambient temperature, use Equation 2 and Equation 3.

Equation 2. TPS22951 eq_thrm_slvsci4.gif

where

  • PD(max) = maximum allowable power dissipation
  • TJ(max) = maximum allowable junction temperature (85°C for the TPS22951)
  • TA = ambient temperature of the device
  • RθJA = junction to air thermal impedance. See thermal metrics table. This parameter is highly dependent upon board layout.
Equation 3. PD = I2 × R