SFFS757 February   2024 DLP4620S-Q1 , DLPC231S-Q1

 

  1.   1
  2. 1Introduction
    1.     Trademarks
  3. 2 DLP4620S-Q1 Chipset Functional Safety Capability
  4. 3Development Process for Management of Systematic Faults
    1. 3.1 TI New-Product Development Process
    2. 3.2 TI Functional Safety Development Process
  5. 4 DLP4620S-Q1 Chipset Overview
    1. 4.1 Targeted Applications
    2. 4.2 DLP4620S-Q1 Chipset Functional Safety Concept
      1. 4.2.1 Typical Hazards
      2. 4.2.2 Chipset Architecture
      3. 4.2.3 Built-In Self Tests
    3. 4.3 Functional Safety Constraints and Assumptions
  6. 5Description of Hardware Component Parts
    1. 5.1 Description of System Level Built In Self Test (BISTs)
  7. 6Management of Random Faults
    1. 6.1 Fault Reporting
      1. 6.1.1 HOST_IRQ
      2. 6.1.2 Error History
      3. 6.1.3 Fault Handling
    2. 6.2 Functional Safety Mechanism Categories
    3. 6.3 Description of Functional Safety Mechanisms
      1. 6.3.1 Video Path Protection
        1. 6.3.1.1 Video Input BISTs
        2. 6.3.1.2 Video Processing BISTs
        3. 6.3.1.3 Video Output BISTs
      2. 6.3.2 Illumination Control Protection
        1. 6.3.2.1 Communication Interface and Register Protection
        2. 6.3.2.2 LED Control Feedback Loop Protection
        3. 6.3.2.3 Data Load and Transfer Protection
        4. 6.3.2.4 Watchdogs and Clock Monitors
        5. 6.3.2.5 Voltage Monitors
  8.   A Summary of Recommended Functional Safety Mechanism Usage
  9.   B Distributed Developments
    1.     B.1 How the Functional Safety Lifecycle Applies to TI Functional Safety Products
    2.     B.2 Activities Performed by Texas Instruments
    3.     B.3 Information Provided
  10.   C Revision History

6.3.2 Illumination Control Protection

The LEDs in the system should be properly controlled to prevent a bright image. In cases where proper control is not possible, the illumination should be turned off.

The DLP4620S-Q1 chipset includes several features to monitoring the illumination control and turn off the LEDs in case of a fault.

Figure 6-6 and Figure 6-7 show the illumination control and LED driver architecture. Figure 6-8 shows the origin and destination of software, data, and settings.

GUID-20240130-SS0I-SH25-VBGW-JPTKSP9LJQ2C-low.svg Figure 6-6 Illumination Control Architecture
GUID-20240130-SS0I-D8XV-0FLB-KZ4WQSN23NWS-low.svg Figure 6-7 LED Driver Architecture
GUID-20240130-SS0I-KKZ3-W6CK-JQ30KKBGLXZK-low.svg Figure 6-8 Software and Settings Origin and Destination

As seen in Figure 6-6, Figure 6-7, and Figure 6-8:

  • At start-up, the Boot ROM commands External Flash to load the Main Application Software and calibration data into the internal RAM (IRAM) of the DLPC231S-Q1. The ARM Core in the DLPC231S-Q1 executes the main application loaded in to the IRAM.
  • The host MCU sends dimming commands periodically to the DLPC231S-Q1 to specify the brightness level of the system. At start-up, the calibration data provides a default dimming level.
  • Based on the dimming level and calibration data, the DLPC231S-Q1 Software determines the correct LED sequence and TPS99000S-Q1 register settings. The LED sequence is the order and timing of LED pulses. TPS99000S-Q1 register settings determine the brightness of the LED pulses.
  • The LED sequence determined by calibration data is requested to be loaded from external flash to the sequencer memory. The sequencer block uses the sequence loaded into its memory to send LED select signals to the TPS99000S-Q1. These signals control the enable and disable for individual LEDs.
  • LED brightness is regulated to the level requested by the DLPC231S-Q1 via a feedback loop consisting of the TPS99000S-Q1, LM3409, the LEDs, and a photo-diode. The brightness target is set by the DLPC231S-Q1 into a DAC in the TPS99000S-Q1. LED brightness is measured by a photo-diode and trans-impedance amplifier (TIA) inside the TPS99000S-Q1. The target brightness and the measured brightness are compared by a comparator in the TPS99000S-Q1. The output of the comparator is used for hysteretic control of the LED light level.

Figure 6-9 shows an overview of all of the monitoring and diagnostics BISTs included in the DLP4620S-Q1 chipset.

GUID-20240130-SS0I-FTZC-QVJZ-QHLCSNDDPL4X-low.svg Figure 6-9 Illumination Control Architecture With Diagnostics