SBVS067R January   2006  – December 2019 TPS737


  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Typical Application Circuit
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Output Noise
      2. 7.3.2 Internal Current Limit
      3. 7.3.3 Enable Pin and Shutdown
      4. 7.3.4 Reverse Current
    4. 7.4 Device Functional Modes
  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. Input and Output Capacitor Requirements
        2. Dropout Voltage
        3. Transient Response
      3. 8.2.3 Application Curves
    3. 8.3 What To Do and What Not To Do
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Power Dissipation
      2. 10.1.2 Thermal Protection
      3. 10.1.3 Estimating Junction Temperature
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. Evaluation Modules
        2. Spice Models
      2. 11.1.2 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

Power Dissipation

Knowing the device power dissipation and proper sizing of the thermal plane that is connected to the tab or pad is critical to avoiding thermal shutdown and ensuring reliable operation.

Power dissipation of the device depends on input voltage and load conditions and can be calculated using Equation 6:

Equation 6. TPS737 q_pd_bvs064.gif

Power dissipation can be minimized and greater efficiency can be achieved by using the lowest possible input voltage necessary to achieve the required output voltage regulation.

On both SON (DRB) and SON (DRV) packages, the primary conduction path for heat is through the exposed pad to the printed circuit board (PCB). The pad can be connected to ground or be left floating; however, it should be attached to an appropriate amount of copper PCB area to ensure the device does not overheat. On the SOT-223 (DCQ) package, the primary conduction path for heat is through the tab to the PCB. That tab should be connected to ground. The maximum junction-to-ambient thermal resistance depends on the maximum ambient temperature, maximum device junction temperature, and power dissipation of the device and can be calculated using Equation 7:

Equation 7. TPS737 q_rth_bvs064.gif

Knowing the maximum RθJA, the minimum amount of PCB copper area needed for appropriate heatsinking can be estimated using Figure 36.

TPS737 ai_theta_ja_bvs067.gif


θJA value at board size of 9 in2 (that is, 3 in × 3 in) is a JEDEC standard.
Figure 36. θJA vs Board Size

Figure 36 shows the variation of θJA as a function of ground plane copper area in the board. It is intended only as a guideline to demonstrate the effects of heat spreading in the ground plane and should not be used to estimate actual thermal performance in real application environments.


When the device is mounted on an application PCB, TI strongly recommends using ΨJT and ΨJB, as explained in the section.