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

8.3.2.3 Illumination Driver A

The illumination driver of the DLPA3000 is a buck converter with two internal low-ohmic N-channel FETs (see Figure 8-6). The theory of operation of a buck converter is explained in Understanding Buck Power Stages in Switchmode Power Supplies. For proper operation, selection of the external components is very important, especially the inductor LOUT and the output capacitor COUT. For best efficiency and ripple performance, an inductor and capacitor should be chosen with low equivalent series resistance (ESR). Set the voltage rating of the capacitor equal or greater than two times of the applied voltage across the capacitor in the application.

GUID-20230628-SS0I-SBWS-9Z88-C0JBFRSKDPFB-low.gif Figure 8-6 Typical Illumination Driver Configuration

Several factors determine the component selection of the buck converter, such as input voltage (SYSPWR), desired output voltage (VLED) and the allowed output current ripple. Configuration starts with selecting the inductor LOUT.

The value of the inductance of a buck power stage is selected such that the peak-to-peak ripple current flowing in the inductor stays within a certain range. Here, the target is set to have an inductor current ripple, kI_RIPPLE, less than 0.3 (30%). The minimum inductor value can be calculated given the input and output voltage, output current, switching frequency of the buck converter (ƒSWITCH= 600 kHz) and inductor ripple of 0.3 (30%):

Equation 1. GUID-81D3512D-A98D-4B08-B903-661148E5FBC6-low.gif

Example: VIN= 12 V, VOUT= 4.3 V, IOUT= 6 A results in an inductor value of LOUT= 2.7 µH

Once the inductor is selected, the output capacitor COUT can be determined. The value is calculated using the fact that the frequency compensation of the illumination loop has been designed for an LC-tank resonance frequency of 15 kHz:

Equation 2. GUID-08810D4C-0B72-4A1B-9C84-618B146216B5-low.gif

Example: COUT= 41.7 µF given that LOUT= 2.7 µH. A practical value is 2 × 22 µF. Here a parallel connection of two capacitors is chosen to lower the ESR even further.

The selected inductor and capacitor determine the output voltage ripple. The resulting output voltage ripple VLED_RIPPLE is a function of the inductor ripple kI_RIPPLE, output current IOUT, switching frequency ƒSWITCH and the capacitor value COUT:

Equation 3. GUID-7AEA7FDD-F2AD-41FA-A292-ECDBD009047E-low.gif

Example: kI_RIPPLE= 0.3, IOUT= 6 A, ƒSWITCH= 600 kHz and COUT= 44 µF results in an output voltage ripple of VLED_RIPPLE= 8.5 mVpp

As can be seen, this is a relative small ripple.

It is strongly advised to keep the capacitance value low. The larger the capacitor value the more energy is stored. In case of a VLED going down, stored energy needs to be dissipated. This might result in a large discharge current. For a VLED step down from V1 to V2, while the LED current was I1. The theoretical peak reverse current is:

Equation 4. GUID-5DFFF9AB-AF90-4846-8984-D8F2774CDB96-low.gif

For the single-LED case, it is advised to keep COUT at maximum 44 µF.

Two other components need to be selected in the buck converter. The value of the input-capacitor (pin ILLUM_A_VIN) should be equal to or greater than the selected output capacitance COUT, in this case >44 µF. The capacitor between ILLUM_A_SWITCH and ILLUM_A_BOOST is a charge pump capacitor to drive the high side FET. The recommended value is 100 nF.