SLVSAZ9D June   2012  – February 2018 TPS81256

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application
      2.      Efficiency vs Load Current
  4. 4 Revision History
  5. 5 Device Options
  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
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Operation
      2. 8.3.2 Power-Save Mode
      3. 8.3.3 Current Limit Operation, Maximum Output Current
    4. 8.4 Device Functional Modes
      1. 8.4.1 Softstart, Enable
      2. 8.4.2 Load Disconnect and Reverse Current Protection
      3. 8.4.3 Undervoltage Lockout
      4. 8.4.4 Thermal Regulation
      5. 8.4.5 Thermal Shutdown
  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
        1. 9.2.2.1 Output Capacitor Selection CEXT
        2. 9.2.2.2 Input Capacitor Selection
      3. 9.2.3 Application Curves
    3. 9.3 System Examples
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Surface Mount Information
    4. 11.4 Thermal and Reliability Information
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • SIP|9
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.2.2 Input Capacitor Selection

In a dc/dc boost converter, since the input current is continuous, only minimum input capacitance is required. The TPS81256 device integrates a low ESR decoupling capacitor to prevent large voltage transients that can cause misbehavior of the device or interference in other circuits in the system.

For most applications, the input capacitor that is integrated into the TPS81256 should be sufficient. If the application exhibits a noisy or erratic switching frequency, experiment with additional input capacitance to find a remedy. Multilayer ceramic capacitors are an excellent choice for input decoupling of the step-up converter as they have extremely low ESR and are available in small footprints. Additional input capacitors should be located as close as possible to the device.

The TPS81256 uses a tiny ceramic input capacitor. When a ceramic capacitor is combined with trace or cable inductance, such as from a wall adapter, a load step at the output can induce ringing at the VIN pin. This ringing can couple to the output and be mistaken as loop instability or can even damage the part. In this circumstance, additional "bulk" capacitance, such as electrolytic or tantalum, should be placed between the input of the converter and the power source lead to reduce ringing that can occur between the inductance of the power source leads and CI.