DLPS280 October   2024 DLPA3082

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 SPI Timing Parameters
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Description
    3. 6.3 Feature Description
      1. 6.3.1 Supply and Monitoring
        1. 6.3.1.1 Supply
        2. 6.3.1.2 Monitoring
          1. 6.3.1.2.1 Block Faults
          2. 6.3.1.2.2 Thermal Protection
      2. 6.3.2 DMD Supplies
        1. 6.3.2.1 LDO DMD
        2. 6.3.2.2 DMD HV Regulator
        3. 6.3.2.3 DMD/DLPC Buck Converters
        4. 6.3.2.4 DMD Monitoring
          1. 6.3.2.4.1 Power Good
          2. 6.3.2.4.2 Overvoltage Fault
      3. 6.3.3 Buck Converters
        1. 6.3.3.1 LDO Bucks
        2. 6.3.3.2 General Purpose Buck Converters
        3. 6.3.3.3 Buck Converter Monitoring
          1. 6.3.3.3.1 Power Good
          2. 6.3.3.3.2 Overvoltage Fault
        4. 6.3.3.4 Buck Converter Efficiency
      4. 6.3.4 Auxiliary LDOs
      5. 6.3.5 Measurement System
    4. 6.4 Device Functional Modes
    5. 6.5 Programming
      1. 6.5.1 SPI
      2. 6.5.2 Interrupt
      3. 6.5.3 Fast-Shutdown in Case of Fault
    6. 6.6 Register Maps
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Component Selection for General-Purpose Buck Converter
    3. 7.3 System Example with DLPA3082 Internal Block Diagram
    4. 7.4 Power Supply Recommendations
      1. 7.4.1 Power-Up and Power-Down Timing
    5. 7.5 Layout
      1. 7.5.1 Layout Guidelines
        1. 7.5.1.1 SPI Connections
      2. 7.5.2 Layout Example
      3. 7.5.3 Thermal Considerations
  9. 8 Device and Documentation Support
    1. 8.1 Third-Party Products Disclaimer
    2. 8.2 Device Support
      1. 8.2.1 Device Nomenclature
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

7.5.3 Thermal Considerations

Power dissipation must be considered when implementing integrated circuits in low-profile and fine-pitch surface-mount packages. Many system-related issues affect power dissipation: thermal coupling, airflow, adding heat sinks and convection surfaces, and the presence of other heat-generating components. In general,there are three basic methods that can be used to improve thermal performance:

  • Improving the heat-sinking capability of the PCB
  • Reducing thermal resistance to the environment of the chip by adding or increasing heat sink capability on top of the package
  • Adding or

    increasing

    airflow in the system

The recommended junction temperature for the DLPA3082 is below 120°C during operation. The equation that relates junction temperature, Tjunction, is given by:

Equation 1. DLPA3082

where Tambient is the ambient temperature, Pdiss is the total power dissipation, and RθJA is the thermal resistance from junction to ambient.

The total power dissipation can vary depending on the application of the DLPA3082. The main contributors in the DLPA3082 are typically:

  • Buck converters
  • LDOs

For the buck converter, the power dissipation is given by:

Equation 2. DLPA3082

where ηbuck is the efficiency of the buck converter, Pin is the power delivered to the input of the buck converter, and Pout is the power delivered to the load of the buck converter. For the buck converter PWR1,2,6, the efficiency can be determined using the curves in Figure 6-6.

For the LDO, the power dissipation is given by:

Equation 3. DLPA3082

where Vin is the input supply voltage, Vout is the output voltage of the LDO, and Iload is the load current of the LDO. The voltage drop over the LDO (Vin–Vout) can be relatively large; a small load current can result in significant power dissipation. For this situation, a general-purpose buck converter can be a more efficient solution.

The LDO DMD provides power to the boost converter, and the boost converter provides high voltages for the DMD; that is, VBIAS, VOFS, and VRST. The current load on these lines can increase up to Iload, max = 10mA. Assuming the efficiency of the boost converter, ηboost is 80%, the maximum boost converter power dissipation, Pdiss_DMD_boost, max, can be calculated as:

Equation 4. DLPA3082

In general, the power dissipation of the boost converter is negligible. However, the power dissipation of the LDO DMD, Pdiss_LDO_DMD must be considered in the case of a high supply voltage. The worst-case load current for the LDO is given by:

Equation 5. DLPA3082

where the output voltage of the LDO is VDRST_5P5V= 5.5V.

The worst-case power dissipation of the LDO DMD is approximately 1.5W when the input supply voltage is 19.5V. For your specific application, check the LDO current level. Therefore, the total power dissipation of the DLPA3082 can be described as:

Equation 6. P d i s s _ D L P A 3082 = ∑ P b u c k _ c o n v e r t e r + ∑ P L D O s

The following examples calculate the maximum ambient temperature and the junction temperature based on known information.

If it is assumed that the total dissipation Pdiss_DLPA3082= 2.5W, Tjunction,max= 120°C, and RθJA= 7°C/W (refer to Section 5.4), then the maximum ambient temperature can be calculated using Equation 1.

Equation 7. DLPA3082

If the total power dissipation and the ambient temperature are known as:

Equation 8. Tambient= 50°C, RθJA= 7°C/W, Pdiss_DLPA3082= 4W.

the junction temperature can be calculated:

Equation 9. DLPA3082

If the combination of ambient temperature and the total power dissipation of the DLPA3082 does not produce an acceptable junction temperature, that is, <120°C, there are two approaches:

  1. Use a larger heat sink or more airflow to reduce RθJA.
  2. Reduce power dissipation in DLPA3082:
    • Use an external buck converter instead of an internal general-purpose buck converter.
    • Reduce load current for the buck converter.