SBVS083E January   2007  – January 2015 TPS780

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration 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 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Internal Current Limit
      2. 7.3.2 Shutdown
      3. 7.3.3 Active VOUT Pulldown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Dropout Operation
      3. 7.4.3 Disabled
    5. 7.5 Programming
      1. 7.5.1 Programming the TPS78001 Adjustable LDO Regulator
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input and Output Capacitor Requirements
        2. 8.2.2.2 Dropout Voltage
        3. 8.2.2.3 Transient Response
        4. 8.2.2.4 Minimum Load
      3. 8.2.3 Application Curves
    3. 8.3 Do's and Don'ts
  9. 9 Power Supply Recommendations
    1. 9.1 Powering the MSP430 Microcontroller
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Board Layout Recommendations to Improve PSRR and Noise Performance
      2. 10.1.2 Package Mounting
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
    4. 10.4 Power Dissipation
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Evaluation Modules
        2. 11.1.1.2 Spice Models
      2. 11.1.2 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

10 Layout

10.1 Layout Guidelines

10.1.1 Board Layout Recommendations to Improve PSRR and Noise Performance

To improve ac performance (such as PSRR, output noise, and transient response), design the printed circuit board (PCB) with separate ground planes for VIN and VOUT, with each ground plane connected only at the GND pin of the device. In addition, the output capacitor must be as close as possible to the ground pin of the device to provide a common reference for regulation purposes. High ESR capacitors may degrade PSRR.

10.1.2 Package Mounting

Solder pad footprint recommendations for the TPS780 series are available from the Texas Instruments web site at www.ti.com through the TPS780 series product folders.

10.2 Layout Example

ai_pcb_dbv_layout_bvs115.gifFigure 61. TPS780xx DDC Package Layout Example

10.3 Thermal Considerations

Thermal protection disables the device output when the junction temperature rises to approximately 160°C, allowing the device to cool. After the junction temperature cools to approximately 140°C, the output circuitry is enabled. Depending on power dissipation, thermal resistance, and ambient temperature, the thermal protection circuit may cycle on and off again. This cycling limits the dissipation of the regulator, protecting it from damage as a result of overheating.

Any tendency to activate the thermal protection circuit indicates excessive power dissipation or an inadequate heatsink. For reliable operation, limit junction temperature to 105°C maximum. To estimate the margin of safety in a complete design (including heatsink), increase the ambient temperature until the thermal protection is triggered; use worst-case loads and signal conditions.

The internal protection circuitry of the TPS780 family is designed to protect against overload conditions. However, this circuitry is not intended to replace proper heatsinking. Continuously running the TPS780 series into thermal shutdown degrades device reliability.

10.4 Power Dissipation

The ability to remove heat from the die is different for each package type, presenting different considerations in the PCB layout. The PCB area around the device that is free of other components moves the heat from the device to the ambient air. Performance data for JEDEC low- and high-K boards are given in Thermal Information. Using heavier copper increases the effectiveness in removing heat from the device. The addition of plated through-holes to heat-dissipating layers also improves the heatsink effectiveness. Power dissipation depends on input voltage and load conditions. Power dissipation (PD) is equal to the product of the output current times the voltage drop across the output pass element (VIN to VOUT), as shown in Equation 3:

Equation 3. q_pd_bvs115.gif