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

10.1.5 LED Connection

Large switched currents flow through the wiring from the external RGB switches to the LEDs. Consider these two specifications to optimize the LED-to-RGB switches wiring layout:

  1. wiring resistancce, RSERIES
  2. wiring inductance, LSERIES

Figure 32 shows the parasitic series impedances.

DLPA4000 Illum_Parasitic_Inductance.gifFigure 32. Parasitic Inductance (LSeries) and Resistance (Rseries) in Series with LED

Currents up to 32 A can flow through the wires connecting the LEDs to the RGB switches. The layout can cause noticeable dissipation. Every 10 mΩ of series resistances implies a parasitic power dissipation of 5 W for a 32 A (avg) LED current . This dissipation can cause an increase in PCB temperature, and more importantly, deterioration of overall system efficiency.

The wiring resistance may impact the control dynamics of the LED current. The LED current control loop includes the routing resistance. The LED voltage (VLED) controlls the LED current. Use Equation 15 to calculate the total differential resistance of a path RSERIES.

Equation 15.

where

    DLPA4000 q_deltailed_dlps132.gif
  • ΔILED is the LED current variation
  • ΔVLED is a small change in VLED
  • rLED is the differential resistance of the LED
  • Ron_SW_P,Q,R the on-resistance of the strobe decoder switch
  • LSERIES is ignored

Equation 15 ignores LSERIES because realistic values are usually sufficiently low to cause any noticeable impact on the dynamics

All differential resistance values range from about 4 mΩ to several hundreds of mΩ. Applications can yield a series resistance of 100 mΩ if the layout guidelines are not followed. Make sure the application series resistance is <10 mΩ.

The series inductance plays an important role when considering the switched nature of the LED current. the current switches through R,G and B LEDs quickly. The turn-off time is significantly fast. A current of 32 A goes to 0 A in 50 ns. This speed causes a voltage spike of approximately 1 V for every 5 nH of parasitic inductance. Minimize the series inductance of the LED wiring by designing an application that has these features:

  • Short wires
  • Thick wires or multiple parallel wires
  • Small enclosed area of the forward and return current path

Use a diode when the application cannot be designed to yield a sufficiently low inductance. Use a Zener diode to clamp the drain voltage of the RGB switch so that it remains below the absolute maximum rating. Choose a clamping voltage between the maximum expected VLED and the absolute maximum rating. Make sure the clamping voltage has sufficient margin relative to the minimum and maximum voltage.