DLPS132 May   2018 DLPA4000

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      System Block 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 SPI Timing Parameters
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Description
    3. 7.3 Feature Description
      1. 7.3.1 Supply and Monitoring
        1. 7.3.1.1 Supply
        2. 7.3.1.2 Monitoring
          1. 7.3.1.2.1 Block Faults
          2. 7.3.1.2.2 Low Battery and UVLO
          3. 7.3.1.2.3 Thermal Protection
      2. 7.3.2 Illumination
        1. 7.3.2.1 Programmable Gain Block
        2. 7.3.2.2 LDO Illumination
        3. 7.3.2.3 Illumination Driver A
        4. 7.3.2.4 External MOSFETs
          1. 7.3.2.4.1 Gate series resistor (RG)
          2. 7.3.2.4.2 Gate series diode (DG)
          3. 7.3.2.4.3 Gate parallel capacitance (CG)
        5. 7.3.2.5 RGB Strobe Decoder
          1. 7.3.2.5.1 Break Before Make (BBM)
          2. 7.3.2.5.2 Openloop Voltage
          3. 7.3.2.5.3 Transient Current Limit
        6. 7.3.2.6 Illumination Monitoring
          1. 7.3.2.6.1 Power Good
          2. 7.3.2.6.2 RatioMetric Overvoltage Protection
      3. 7.3.3 External Power MOSFET Selection
        1. 7.3.3.1 Threshold Voltage
        2. 7.3.3.2 Gate Charge and Gate Timing
        3. 7.3.3.3 On-resistance RDS(on)
      4. 7.3.4 DMD Supplies
        1. 7.3.4.1 LDO DMD
        2. 7.3.4.2 DMD HV Regulator
        3. 7.3.4.3 DMD/DLPC Buck Converters
        4. 7.3.4.4 DMD Monitoring
          1. 7.3.4.4.1 Power Good
          2. 7.3.4.4.2 Overvoltage Fault
      5. 7.3.5 Buck Converters
        1. 7.3.5.1 LDO Bucks
        2. 7.3.5.2 General Purpose Buck Converters
        3. 7.3.5.3 Buck Converter Monitoring
          1. 7.3.5.3.1 Power Good
          2. 7.3.5.3.2 Overvoltage Fault
      6. 7.3.6 Auxiliary LDOs
      7. 7.3.7 Measurement System
    4. 7.4 Device Functional Modes
    5. 7.5 Programming
      1. 7.5.1 SPI
      2. 7.5.2 Interrupt
      3. 7.5.3 Fast-Shutdown in Case of Fault
      4. 7.5.4 Protected Registers
      5. 7.5.5 Writing to EEPROM
    6. 7.6 Register Maps
  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 Component Selection for General-Purpose Buck Converters
    3. 8.3 System Example With DLPA4000 Internal Block Diagram
  9. 9 Power Supply Recommendations
    1. 9.1 Power-Up and Power-Down Timing
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 LED Driver
        1. 10.1.1.1 PowerBlock Gate Control Isolation
        2. 10.1.1.2 VIN to PowerBlocks
        3. 10.1.1.3 Return Current from LEDs and RSense
        4. 10.1.1.4 RC Snubber
        5. 10.1.1.5 Capacitor Choice
      2. 10.1.2 General Purpose Buck 2
      3. 10.1.3 SPI Connections
      4. 10.1.4 RLIM Routing
      5. 10.1.5 LED Connection
    2. 10.2 Layout Example
    3. 10.3 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Device Nomenclature
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Package Option Addendum
      1. 12.1.1 Packaging Information

Package Options

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

10.3 Thermal Considerations

Integrated circuits in low-profile and fine-pitch surface-mount packages typically require special attention to power dissipation. Many different system-dependent issues affect the power dissipation limits of individual component. These issues include

  • thermal coupling
  • airflow
  • added heat sinks
  • added convection surfaces
  • other heat-generating components

These three basic approaches enhance thermal performance.

  • Improve the heat sinking capability of the PCB
  • Increase heat sink capability on top of the package
  • Increase airflow in the system

The DLPA4000 device has efficient power converters. But because the power delivered to the LEDs can be quite large (more than 50 W in some case) the power dissipation in the DLPA4000 device can be high. Use proper temperature calculation to minimize power dissipation in the application.

It is important to maintain the junction temperature below the maximum recommended value of 120°C during operation. Calculate PDISS, to determine the junction temperature of the DLPA4000. PDISS is a summation of all power dissipation. Use Equation 16 to calculate TJ.

Equation 16. DLPA4000 q_tj1_dlps132.gif

where

  • TA is the ambient temperature
  • RθJA is the thermal resistance from junction-to-ambient

The total power dissipation varies depending on the application specifications. The main variances in the DLPA4000 circuitry are:

  • Buck converters
  • LDOs

Use Equation 17 to calculate the dissipation for the buck converter.

Equation 17. DLPA4000 EQ_therm_PD_buck.gif

where

  • ηBUCK is the efficiency of the buck converter
  • PIN the power delivered at the input of the buck converter
  • POUT the power delivered to the load of the buck converter

shows efficiency for buck converters PWR1, PWR2, PWR5, PWR6, and PWR7.

Buck converters require high power efficiency because they typically handle the highest power levels. Linear regulators,(for example, LDOs) handle lower power levels. Because the efficiency of an LDO can be relative low, the related power dissipation can be significant.

Use Equation 18 to calculate the power dissipation of an LDO, PDISS(ldo).

Equation 18. DLPA4000 q_pdissldoj_dlps132.gif

where

  • VIN is the input supply voltage
  • VOUT is the output voltage of the LDO
  • ILOAD is the load current of the LDO

Because the voltage decrease over the LDO (VIN – VOUT) can be relative large, a relatively small load current can yield significant power dissipation in the DLPA4000 device. In this case, consider using one of the general purpose bucks to have a more power-efficient solition (in other words, a less dissipation solution).

It is important to consider the power dissipation of the LDO that supplies the boost power converter (the LDO DMD). The boost converter supplies high voltages for the DMD. This voltages are VBIAS, VOFS, VRST.The maximum simultaneous load current ILOAD(max) for these lines is 10 mA . So, the maximum related power level is moderate. Use Equation 19 An efficiency rate of 80% for the boost converter, ηBOOST, implies a maximum boost converter dissipation, PDISS (DMD_boost,MAX).

Equation 19. DLPA4000 q_pdissdmdboostmax_dlps132.gif

The level of power dissipation of the illumination buck converter this is likely negligible. The term that might count to the total power dissipation is Pdiss_LDO_DMD. The input current of the DMD boost converter is supplied by this LDO. In case of an high supply voltage, a non negligible dissipation term is obtained. The worst case load current for the LDO is given by:

Equation 20. DLPA4000 q_iloadldomax_dlps132.gif

where

  • the output voltage of the LDO is VDRST_5P5V is 5.5 V

Dissipation of power in the LDO can be up to 1.5 W for an input supply voltage of 19.5 V. Power dissipation of 1.5 W is a worst case scenario. In most cases the load current of the LDO DMD is significantly less. Make sure to confirm the LDO current level for the specific application.

The DLPA4000 draws a quiescent current. The power supply voltage does not affect this quiescent current. For the buck converters the quiescent current is comprised in the efficiency numbers. For the LDOs a quiescent current on the order of 0.5 mA can be used. For the rest of the DLPA4000 circuitry, not included in the buck converters or LDOs, a quiescent current on the order of 3 mA applies. Use Equation 21 to estimate dissipation, Pdiss_DLPA4000 in the DLPA4000 device.

Equation 21. DLPA4000 q_pdissdlps4000_dlps132.gif

Use to calculate the maximum ambient temperature,

Equation 22. DLPA4000 q_tj0_dlps132.gif

Use to calculate the junction temperature of the DLPA4000 device after you know the dissipated power and the ambient temperature.

Use Thermal Information to calculate the junction temperature for heat sink configuration and airflow.

Equation 23. DLPA4000 q_tj2_dlps132.gif

Use one of these three design features if the combination of ambient temperature and DLPA4000 power dissipation does not yield an acceptable junction temperature ( <120°C).

  1. Use a larger heat sink, which increases airflow, to reduced RθJA,
  2. Use lower load current through the internal general purpose buck converters..
  3. Use an external general purpose buck converter instead of an internal one. This design reduces power dissipation in the DLPA4000 device