DLPS240A June   2024  – August 2024 DLPA3085

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 SPI Timing Parameters
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Description
    3. 6.3 Feature Description
      1. 6.3.1 Supply and Monitoring
        1. 6.3.1.1 Supply
        2. 6.3.1.2 Monitoring
          1. 6.3.1.2.1 Block Faults
          2. 6.3.1.2.2 Auto LED Turn-Off Functionality
          3. 6.3.1.2.3 Thermal Protection
      2. 6.3.2 Illumination
        1. 6.3.2.1 Programmable Gain Block
        2. 6.3.2.2 LDO Illumination
        3. 6.3.2.3 Illumination Driver A
        4. 6.3.2.4 RGB Strobe Decoder
          1. 6.3.2.4.1 Break Before Make (BBM)
          2. 6.3.2.4.2 Openloop Voltage
          3. 6.3.2.4.3 Transient Current Limit
        5. 6.3.2.5 Illumination Monitoring
          1. 6.3.2.5.1 Power Good
          2. 6.3.2.5.2 Ratio Metric Overvoltage Protection
        6. 6.3.2.6 Illumination Driver Plus Power FETs Efficiency
      3. 6.3.3 External Power FET Selection
        1. 6.3.3.1 Threshold Voltage
        2. 6.3.3.2 Gate Charge and Gate Timing
        3. 6.3.3.3 RDS(ON)
      4. 6.3.4 DMD Supplies
        1. 6.3.4.1 LDO DMD
        2. 6.3.4.2 DMD HV Regulator
        3. 6.3.4.3 DMD/DLPC Buck Converters
        4. 6.3.4.4 DMD Monitoring
          1. 6.3.4.4.1 Power Good
          2. 6.3.4.4.2 Overvoltage Fault
      5. 6.3.5 Buck Converters
        1. 6.3.5.1 LDO Bucks
        2. 6.3.5.2 General Purpose Buck Converters
        3. 6.3.5.3 Buck Converter Monitoring
          1. 6.3.5.3.1 Power Good
          2. 6.3.5.3.2 Overvoltage Fault
        4. 6.3.5.4 Buck Converter Efficiency
      6. 6.3.6 Auxiliary LDOs
      7. 6.3.7 Measurement System
    4. 6.4 Device Functional Modes
    5. 6.5 Programming
      1. 6.5.1 SPI
      2. 6.5.2 Interrupt
      3. 6.5.3 Fast-Shutdown in Case of Fault
    6. 6.6 Register Maps
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Component Selection for General-Purpose Buck Converter
      3. 7.2.3 Application Curve
    3. 7.3 System Example With DLPA3085 Internal Block Diagram
  9. 8 Power Supply Recommendations
    1. 8.1 Power-Up and Power-Down Timing
  10. 9 Layout
    1. 9.1 Layout Guidelines
      1. 9.1.1 SPI Connections
      2. 9.1.2 RLIM Routing
      3. 9.1.3 LED Connection
    2. 9.2 Layout Example
    3. 9.3 Thermal Considerations
  11. 10Device and Documentation Support
    1. 10.1 Third-Party Products Disclaimer
    2. 10.2 Device Support
      1. 10.2.1 Device Nomenclature
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 Support Resources
    5. 10.5 Trademarks
    6. 10.6 Electrostatic Discharge Caution
    7. 10.7 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9.1.3 LED Connection

High switching currents run through the wiring connecting the external RGB switches and the LEDs; therefore, this needs special attention. Two perspectives apply to the LED-to-RGB switches wiring:

  1. The resistance of the wiring, Rseries
  2. The inductance of the wiring, Lseries

The location of the parasitic series impedances is depicted in Figure 9-3.

DLPA3085 Parasitic Inductance (LSeries) and Resistance (Rseries) in Series with LEDFigure 9-3 Parasitic Inductance (LSeries) and Resistance (Rseries) in Series with LED

Currents up to 16A can run through the wires connecting the LEDs to the RGB switches. Some noticeable dissipation can be caused. Every 10mΩ of series resistances implies for 16A average LED current a parasitic power dissipation of 2.5W. This might cause PCB heating, but more importantly, overall system efficiency deteriorates.

Additionally, the resistance of the wiring might impact the control dynamics of the LED current. It should be noted that the routing resistance is part of the LED current control loop. The LED current is controlled by VLED. For a small change in VLED (ΔVLED), the resulting LED current variation (ΔILED) is given by the total differential resistance in that path, as:

Equation 12.
DLPA3085
  • rLED is the differential resistance of the LED.
  • Ron_SW_P,Q,R the on-resistance of the strobe decoder switch.

In this expression, Lseries is ignored because realistic values are usually sufficiently low to cause any noticeable impact on the dynamics.

All the comprising differential resistances are in the range of 12.5mΩ to several 100mΩ. Without paying special attention, a series resistance of 100mΩ can easily be obtained. It is advised to keep this series resistance sufficiently low; that is, <10mΩ.

The series inductance plays an important role when considering the switched nature of the LED current. While cycling through R, G, and B LEDs, the current through these branches is turned on and turned off in short time duration. Specifically turning off is fast. A current of 16A goes to 0A in a matter of 50ns. This implies a voltage spike of about 1V for every 5nH of parasitic inductance. Minimize the series inductance of the LED wiring with the following:

  • Short wires
  • Thick wires / multiple parallel wires
  • The small enclosed area of the forward and return current path

If the inductance cannot be made sufficiently low, use a Zener diode to clamp the drain voltage of the RGB switch so it does not surpass the absolute maximum rating. Choose the clamping voltage between the maximum expected VLED and the absolute maximum rating. Ensure a sufficient margin of the clamping voltage relative to the mentioned minimum and maximum voltage.