DLPS052A October   2015  – September 2023 DLPA3000

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Description (cont.)
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 SPI Timing Parameters
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Supply and Monitoring
        1. 8.3.1.1 Supply
        2. 8.3.1.2 Monitoring
          1. 8.3.1.2.1 Block Faults
          2. 8.3.1.2.2 Low Battery and UVLO
          3. 8.3.1.2.3 Auto LED Turn Off Functionality
          4. 8.3.1.2.4 Thermal Protection
      2. 8.3.2 Illumination
        1. 8.3.2.1 Programmable Gain Block
        2. 8.3.2.2 LDO Illum
        3. 8.3.2.3 Illumination Driver A
        4. 8.3.2.4 RGB Strobe Decoder
          1. 8.3.2.4.1 Break Before Make (BBM)
          2. 8.3.2.4.2 Openloop Voltage
          3. 8.3.2.4.3 Transient Current Limit
        5. 8.3.2.5 Illumination Monitoring
          1. 8.3.2.5.1 Power Good
          2. 8.3.2.5.2 Ratio Metric Overvoltage Protection
        6. 8.3.2.6 Load Current and Supply Voltage
        7. 8.3.2.7 Illumination Driver Plus Power FETS Efficiency
      3. 8.3.3 DMD Supplies
        1. 8.3.3.1 LDO DMD
        2. 8.3.3.2 DMD HV Regulator
          1. 8.3.3.2.1 Power-Up and Power-Down Timing
        3. 8.3.3.3 DMD/DLPC Buck Converters
        4. 8.3.3.4 DMD Monitoring
          1. 8.3.3.4.1 Power Good
          2. 8.3.3.4.2 Overvoltage Fault
      4. 8.3.4 Buck Converters
        1. 8.3.4.1 LDO Bucks
        2. 8.3.4.2 General Purpose Buck Converters
        3. 8.3.4.3 Buck Converter Monitoring
          1. 8.3.4.3.1 Power Good
          2. 8.3.4.3.2 Overvoltage Fault
        4. 8.3.4.4 Buck Converter Efficiency
      5. 8.3.5 Auxiliary LDOs
      6. 8.3.6 Measurement System
      7. 8.3.7 Digital Control
        1. 8.3.7.1 SPI
        2. 8.3.7.2 Interrupt
        3. 8.3.7.3 Fast-Shutdown in Case of Fault
    4. 8.4 Device Functional Modes
    5. 8.5 Register Maps
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Typical Application Setup Using DLPA3000
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curve
      2. 9.2.2 Typical Application with DLPA3000 Internal Block Diagram
  11. 10Power Supply Recommendations
  12. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 SPI Connections
    4. 11.4 RLIM Routing
    5. 11.5 LED Connection
    6. 11.6 Thermal Considerations
  13. 12Device and Documentation Support
    1. 12.1 Third-Party Products Disclaimer
    2. 12.2 Device Support
      1. 12.2.1 Device Nomenclature
    3. 12.3 Related Links
    4. 12.4 Receiving Notification of Documentation Updates
    5. 12.5 Support Resources
    6. 12.6 Trademarks
    7. 12.7 Support Resources
    8. 12.8 Electrostatic Discharge Caution
    9. 12.9 Glossary
  14. 13Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.2.1 Programmable Gain Block

The current through the LEDs is determined by a digital number stored in the respective SWx_IDAC(x) registers (0x03 to 0x08). 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 SWx_IDAC(x) registers (0x03 to 0x08) and the loop regulates the current to its set value.

GUID-A062A402-CC7B-41F5-A21C-9B55917C14DB-low.gif Figure 8-5 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 of up to 6 A.

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

For instance, when two LEDs are connected in series, 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 is shortened. The loop gain is set to a default value which achieves good performance and no further adjustments are necessary.

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 maintain the proper functioning of the ILED current loop.