SLVS749C November   2008  – January 2015 TPS22921 , TPS22922

UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Typical Application
  5. 5 Revision History
  6. 6 Device Comparison Table
  7. 7 Pin Configuration and Functions
  8. 8 Specifications
    1. 8.1  Absolute Maximum Ratings
    2. 8.2  ESD Ratings
    3. 8.3  Recommended Operating Conditions
    4. 8.4  Thermal Information
    5. 8.5  Electrical Characteristics
    6. 8.6  Switching Characteristics: VIN = 0.9 V
    7. 8.7  Switching Characteristics: VIN = 1 V
    8. 8.8  Switching Characteristics: VIN = 1.1 V
    9. 8.9  Switching Characteristics: VIN = 1.2 V
    10. 8.10 Switching Characteristics: VIN = 1.8 V
    11. 8.11 Switching Characteristics: VIN = 2.5 V
    12. 8.12 Switching Characteristics: VIN = 3 V
    13. 8.13 Switching Characteristics: VIN = 3.6 V
    14. 8.14 Typical Characteristics
      1. 8.14.1 Typical DC Characteristics
      2. 8.14.2 Typical AC Characteristics (TPS22921)
      3. 8.14.3 Typical AC Characteristics (TPS22922)
      4. 8.14.4 Typical AC Characteristics (TPS22922B)
      5. 8.14.5 Typical AC Characteristics (TPS22921 and TPS22922)
      6. 8.14.6 Typical AC Characteristics (TPS22921)
      7. 8.14.7 Typical AC Characteristics (TPS22922)
      8. 8.14.8 Typical AC Characteristics (TPS22922B)
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1 ON/OFF Control
      2. 10.3.2 Quick Output Discharge
    4. 10.4 Device Functional Modes
  11. 11Application and Implementation
    1. 11.1 Application Information
      1. 11.1.1 Input Capacitor (Optional)
      2. 11.1.2 Output Capacitor (Optional)
    2. 11.2 Typical Application
      1. 11.2.1 Design Requirements
      2. 11.2.2 Detailed Design Procedure
        1. 11.2.2.1 Managing Inrush Current
        2. 11.2.2.2 VIN to VOUT Voltage Drop
      3. 11.2.3 Application Curve
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
  14. 14Device and Documentation Support
    1. 14.1 Related Links
    2. 14.2 Trademarks
    3. 14.3 Electrostatic Discharge Caution
    4. 14.4 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

13 Layout

13.1 Layout Guidelines

For best performance, VIN, VOUT, and GND traces should be as short and wide as possible to help minimize the parasitic electrical effects. To be most effective, the input and output capacitors should be placed close to the device to minimize the effects that parasitic trace inductances may have on normal operation.

For higher reliability, the maximum IC junction temperature, TJ(max), should be restricted to 125˚C under normal operating conditions. Junction temperature is directly proportional to power dissipation in the device and the two are related by

Equation 5. TJ = TA + θJA × PD

where

  • TJ = Junction temperature of the device
  • TA = Ambient temperature
  • PD = Power dissipation inside the device
  • θJA = Junction to ambient thermal resistance. See Thermal Information section of the data sheet. This parameter is highly dependent on board layout.

13.2 Layout Example

TPS2292122 Drawing.jpgFigure 55. Layout Recommendation