DLPS052 October   2015 DLPA3000

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      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 Diagram
    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 Auto LED Turn Off Functionality
          4. 7.3.1.2.4 Thermal Protection
      2. 7.3.2 Illumination
        1. 7.3.2.1 Programmable Gain Block
        2. 7.3.2.2 LDO Illum
        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 Load Current and Supply Voltage
        7. 7.3.2.7 Illumination Driver Plus Power FETS Efficiency
      3. 7.3.3 DMD Supplies
        1. 7.3.3.1 LDO DMD
        2. 7.3.3.2 DMD HV Regulator
          1. 7.3.3.2.1 Power-Up and Power-Down Timing
        3. 7.3.3.3 DMD/DLPC Buck Converters
        4. 7.3.3.4 DMD Monitoring
          1. 7.3.3.4.1 Power Good
          2. 7.3.3.4.2 Overvoltage Fault
      4. 7.3.4 Buck Converters
        1. 7.3.4.1 LDO Bucks
        2. 7.3.4.2 General Purpose Buck Converters
        3. 7.3.4.3 Buck Converter Monitoring
          1. 7.3.4.3.1 Power Good
          2. 7.3.4.3.2 Overvoltage Fault
        4. 7.3.4.4 Buck Converter Efficiency
      5. 7.3.5 Auxiliary LDOs
      6. 7.3.6 Measurement System
      7. 7.3.7 Digital Control
        1. 7.3.7.1 SPI
        2. 7.3.7.2 Interrupt
        3. 7.3.7.3 Fast-Shutdown in Case of Fault
        4. 7.3.7.4 Protected Registers
        5. 7.3.7.5 Writing to EEPROM
    4. 7.4 Device Functional Modes
    5. 7.5 Register Maps
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Application Setup Using DLPA3000
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Typical Application with DLPA3000 Internal Block Diagram
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 SPI Connections
    4. 10.4 RLIM Routing
    5. 10.5 LED Connection
    6. 10.6 Thermal Considerations
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Device Nomenclature
    2. 11.2 Related Links
    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)

7.3.2.5.2 Ratio Metric Overvoltage Protection

The DLPA3000 illumination driver LED outputs are protected against open circuit use. In case no LED is connected and the PAD device is instructed to set the LED current to a specific level, the LED voltage (ILLUM_A_FB) will quickly rise and potentially rail to VIN. This should be prevented. The OVP protection circuit triggers once VLED crosses a predefined level. As a result the DLPA3000 will be switched off.

The same protection circuit is triggered in case the supply voltage (VINA) will become too low to have the DLPA3000 work properly given the VLED level. This protection circuit is constructed around a comparator that will sense both the LED voltage and the VINA supply voltage. The fraction of the VINA is connected to the minus input of the comparator while the fraction of the VLED voltage is connected to the plus input. Triggering occurs when the plus input rises above the minus input and an OVP fault is set. The fraction of the VINA must be set between 1 V and 4 V to ensure proper operation of the comparator.

DLPA3000 OVP_Ratio-Metric.gifFigure 11. Ratio Metric OVP

The fraction of the ILLUM_A_FB voltage is set by the register 0x19h bits [4:0], while the setting of the fraction of the VINA voltage is done by register 0x0Bh bits [4:0]. In general an OVP fault is set when

VLED/VLED_RATIO ≥ VINA/VINA_RATIO
thus when:
VLED ≥ VINA × VLED_RATIO/VINA_RATIO.

Clearly, the OVP level is ratio-metric, i.e. can be set to a fixed fraction of VINA.

For example: VLED should stay below 85% of VINA. The settings for the respective registers are:

  • reg 0x19h [4:0] = 01h (4.98)
  • reg 0x0Bh [4:0] = 07h (5.85)

The result is as follows: OVP triggers if VLED ≥ VINA × 4.98/5.85 = 0.85 VINA.

Additionally, for VIN_RATIO = 5.85, the VIN- input voltage for the comparator is between 1 V and 3.4 V for a supply voltage between 6 V and 20 V.