SBVS318B July   2017  – January 2019 TPS7A92

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Circuit
      2.      Typical Application Diagram
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Output Enable
      2. 7.3.2 Dropout Voltage (VDO)
      3. 7.3.3 Output Voltage Accuracy
      4. 7.3.4 High Power-Supply Ripple Rejection (PSRR)
      5. 7.3.5 Low Output Noise
      6. 7.3.6 Output Soft-Start Control
      7. 7.3.7 Power-Good Function
      8. 7.3.8 Internal Protection Circuitry
        1. 7.3.8.1 Undervoltage Lockout (UVLO)
        2. 7.3.8.2 Internal Current Limit (ICL)
        3. 7.3.8.3 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Dropout Operation
      3. 7.4.3 Disabled
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Adjustable Output
      2. 8.1.2 Start-Up
        1. 8.1.2.1 Enable (EN) and Undervoltage Lockout (UVLO)
        2. 8.1.2.2 Noise-Reduction and Soft-Start Capacitor (CNR/SS)
          1. 8.1.2.2.1 Noise Reduction
          2. 8.1.2.2.2 Soft-Start and Inrush Current
      3. 8.1.3 Capacitor Recommendation
        1. 8.1.3.1 Input and Output Capacitor Requirements (CIN and COUT)
          1. 8.1.3.1.1 Load-Step Transient Response
        2. 8.1.3.2 Feed-Forward Capacitor (CFF)
      4. 8.1.4 Power Dissipation (PD)
      5. 8.1.5 Estimating Junction Temperature
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Board Layout
    2. 10.2 Layout Example
  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 Receiving Notification of Documentation Updates
    4. 11.4 Community 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

8.1.4 Power Dissipation (PD)

Circuit reliability demands that proper consideration be given to device power dissipation, location of the circuit on the printed circuit board (PCB), and correct sizing of the thermal plane. The PCB area around the regulator must be as free as possible of other heat-generating devices that cause added thermal stresses.

To first-order approximation, power dissipation in the regulator depends on the input-to-output voltage difference and load conditions. PD can be calculated using Equation 6:

Equation 6. PD = (VIN – VOUT) × IOUT

An important note is that power dissipation can be minimized, and thus greater efficiency achieved, by proper selection of the system voltage rails. For the lowest power dissipation use the minimum input voltage necessary for proper output regulation.

The primary heat conduction path for the DSK package is through the thermal pad to the PCB. Solder the thermal pad to a copper pad area under the device. This pad area should contain an array of plated vias that conduct heat to additional copper planes for increased heat dissipation.

The maximum power dissipation determines the maximum allowable ambient temperature (TA) for the device. Power dissipation and junction temperature are most often related by the junction-to-ambient thermal resistance (RθJA) of the combined PCB and device package and the temperature of the ambient air (TA), according to Equation 7.

Equation 7. TJ = TA + (RθJA × PD)

Unfortunately, the thermal resistance (θJA) is highly dependent on the heat-spreading capability built into the particular PCB design, and therefore varies according to the total copper area, copper weight, and location of the planes. The RθJA recorded in the Thermal Information table is determined by the JEDEC standard, PCB, and copper-spreading area and is only used as a relative measure of package thermal performance.