DLPS071A October   2015  – February 2023 DLPA3005

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and 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 Auto LED Turn Off Functionality
          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 RGB Strobe Decoder
          1. 7.3.2.4.1 Break Before Make (BBM)
          2. 7.3.2.4.2 Openloop Voltage
          3. 7.3.2.4.3 Transient Current Limit
        5. 7.3.2.5 Illumination Monitoring
          1. 7.3.2.5.1 Power Good
          2. 7.3.2.5.2 Ratio Metric Overvoltage Protection
        6. 7.3.2.6 Illumination Driver plus Power FETs Efficiency
      3. 7.3.3 External Power FET Selection
        1. 7.3.3.1 Threshold Voltage
        2. 7.3.3.2 Gate Charge and Gate Timing
        3. 7.3.3.3 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 Converter
        3. 7.3.5.3 Buck Converter Monitoring
          1. 7.3.5.3.1 Power Good
          2. 7.3.5.3.2 Overvoltage Fault
        4. 7.3.5.4 Buck Converter Efficiency
      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
    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. 8.2.3 Application Curve
    3. 8.3 System Example With DLPA3005 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 SPI Connections
      2. 10.1.2 RLIM Routing
      3. 10.1.3 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 Third-Party Products Disclaimer
    3. 11.3 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Support Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Package Option Addendum

Package Options

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

7.3.2.1 Programmable Gain Block

The current through the LEDs is determined by a digital number stored in the respective SWx_IDAC(x) registers, 0x03h to 0x08h. These registers determine the LED current which is measured through the sense resistor RLIM. The voltage across RLIM is compared with the current setting from the IDAC registers and the loop regulates the current to its set value.

GUID-6A6F0DA5-1629-407C-9A09-8AFD75A2D903-low.gif Figure 7-3 Programmable Gain Block in the Illumination Control Loop

When current is flowing through an LED, a forward voltage is built up over the LED. The LED also represents a (low) differential resistance which is part of the load circuit for VLED. Together with the wire resistance (RWIRE) and the RON resistance of the FET switch a voltage divider is created with RLIM that is a factor in the loop gain of the ILED control. Under normal conditions, the loop is able to produce a well regulated LED current up to 16 Amps.

Since this voltage divider is part of the control loop, care must be taken while designing the system.

When, for instance, two LEDs in series are connected, or when a relatively high wiring resistance is present in the loop, the loop gain will reduce due to the extra attenuation caused by the increased series resistances of rLED + RWIRE +RON. As a result, the loop response time lowers. To compensate for this increased attenuation, the loop gain can be increased by selecting a higher gain for the programmable gain block. The gain increase can be set through register ILLUM_BW_BCx.

Under normal circumstances the default gain setting (00h) is sufficient. In case of a series connection of two LEDs setting 01h or 02h might suffice.

As discussed previously, wiring resistance also impacts the control-loop performance. It is advisable to prevent unnecessary large wire length in the loop. Keeping wiring resistance as low as possible is good for efficiency reasons. In case wiring resistance still impacts the response time of the loop, an appropriate setting of the gain block can be selected. The same goes for connector resistance and PCB tracks. Note that every milliohm (mΩ) counts. These precautions help to ensure the proper functioning of the ILED current loop.