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TIDA-080007 DLP Auto Headlight Reference Design

Description

This reference design details the style of a control board for the DLP5531-Q1 DMD. The DLP5531-Q1 DMD is a spatial light modulator with over 1.3 million pixels that can steer light to produce digitally controlled illumination distributions. The design shows a simplified power architecture having a reduced component count in order to save space and reduce cost

Features

  • OpenLDI video input
  • Reverse voltage and overvoltage protection
  • Brownout detection with safe DMD parking
  • SPI port for host communication
  • I 2C port for diagnostics
  • Spread spectrum to aid automotive EMI requirements like CISPR 25
  • LED enable signals to synchronize LED illumination using the DMD
  • CISPR 25 tested design

Applications

  • High-resolution ADB headlight and high-resolution symbol projection
  • Small light dynamic ground projection

System Description

This product is designed to show how the DLP5531-Q1 DMD, in conjunction with the DLPC230-Q1 DMD controller and TPS99000-Q1 system controller, may be used to modulate incoming light from the number of sources including LED and laser illumination. This design utilizes a wide VIN buck controller to manage the incoming battery voltage for an intermediate 3.3V voltage rail that props up 6.5 V, 1.8 V, and 1.1 V rails which power the DMD controller and system controller. With this architecture the machine can operate over a number of voltage conditions including cranking and quick start conditions. The system features OpenLDI input for video treatments for the DMD mirrors. The DLPC230-Q1 generates illumination control signals that synchronize the illumination to the state from the mirrors. There's a SPI port for command and control in the host processor as well as an I2C port that can be used to see a hardware diagnostic register.

This design, in conjunction with a host processor, video source, and illumination source, may be used to create next-generation high-resolution headlights with individual control of over 1.3 million pixels. This best in class resolution can be used to support applications for example high resolution adaptive driving beam (ADB headlight), symbol projection for vehicle-to-environment communication, and unique welcome lighting distributions that permit customers or OEMs to personalize the finish vehicle.

High resolution is essential for adaptive driving beam applications because it allows much finer treatments for the sunshine distribution. With ADB headlights, you want to be able to switch off part of the light distribution to prevent glare to oncoming drivers. With higher resolution, you are able to switch off an inferior area, thereby keeping more illumination on the highway in which you want it. High resolution also allows you to smoothly slowly move the switched off regions of the sunshine distribution with a smaller amount jitter which can potentially be distracting to drivers.

High resolution can also be crucial for symbol projection applications. For any symbol to be readable and for that reason helpful to the driver in order to pedestrians or other vehicles, there must be enough resolution. In a typical application, the majority of the field of view of a headlight will probably be focused on the primary headlight function and just a small portion to the symbol projection function. With 1.3 million pixels, even if you’re only utilizing a small portion of the field of view, you can still produce a high-quality symbol.

System Overview

Block Diagram

2.2 Design Considerations

Form Factor

The PCB is made to match the shape factor from the DLP5531-Q1 EVM. This is designed so that these electronics can mate with other optical reference designs.

Power Supply Design

The DLP5531-Q1 chipset requires multiple voltage rails. System voltages that support the TPS99000-Q1, DLPC230-Q1, and DLP5531-Q1 logic are supplied by discrete regulators (1.1 V, 1.8 V, 3.3 V, and 6.5 V).

The DMD has specific reset voltages that control the mirror position. They are VRESET (-10 V), VOFFSET (8.5 V), and VBIAS (16 V). Because of the strict tolerances and timing requirements they're provided by the TPS99000-Q1 which was specifically designed for powering the DMD.

The DLP5531-Q1 DMD has strict switch on and power down timing requirements. Often the product is powered up and powered down based on the PROJ_ON signal being asserted by the host processor. In the situation that power loss occurs through and event such as battery being disconnected the system still must park the DMD mirrors and take away power in the correct sequence. This series of events is handled through the TPS99000-Q1. The TPS99000-Q1 continuously monitors the machine voltage. If the system voltage drop below a predefined level the TPS99000-Q1 will instruct the DLPC230 to exit display mode, park the DMD mirrors, and disable the DMD voltages in the correct order. The timing for this sequence of events is supplied in the TPS99000-Q1 data sheet. Enough capacitance should be open to hold up the voltage rail when it comes to a loss of system power. Holdup capacitance can be calculated using Equation 1. A voltage divider on the system voltage monitoring (Vmain) pin of the TPS99000-Q1 sets the trip voltage to begin shutting down the machine at 5.4 V. The LM36015 has a typical dropout voltage of 0.4 V. Assuming worst of all power consumption values for that DLPC230-Q1, TPS99000-Q1, and DLP5531-Q1 along with a required holdup time of 0.9ms we are able to calculate the required capacitance as shown in Equation 2.

Highlighted Products

DLP5531-Q1 0.55-inch 1.3 Megapixel DMD for Automotive Exterior Lighting

  • Qualified for Automotive Applications
    • -40°C to 105°C operating DMD array temperature range
  • 55-inch diagonal micromirror array
    • Bottom illumination for optimal efficiency and optical engine size
    • 3-megapixel array configured by 50 percent:1 aspect ratio enabling high resolution and wide aspect ratio automotive applications
    • Compatible with LED or laser illumination
  • 600-MHz sub-LVDS DMD interface for low power and emission
  • 10-kHz DMD refresh rate over temperature extremes
  • Built-in self test of DMD memory cells

The DLP5531-Q1 Automotive DMD, combined with the DLPC230-Q1 DMD controller and TPS99000-Q1 system management and illumination controller, provides the capacity to achieve high-performance high-resolution headlight systems. The two:1 aspect ratio supports very wide aspect ratio designs, and also the 1.3megapixel resolution enables high resolution symbol projection and adaptive driving beam applications. The DLP5531-Q1 has a lot more than Three times the optical throughput from the preceding DLP3030-Q1 Automotive DMD enabling an even larger field of view and better lumen output. The DLP5531-Q1 Automotive DMD micromirror array is configured for bottom illumination which helps highly efficient and much more compact optical engine designs. The S450 package has low thermal potential to deal with the DMD array to allow more efficient thermal solutions.

DLPC230-Q1 Automotive DMD Controller for that DLP553x-Q1 Chipset

  • AEC-Q100 qualified with the following results:
    • Device temperature grade 2: -40°C to 105°C ambient operating temperature
    • Device HBM ESD classification level 2
    • Device CDM ESD classification level C4B
  • DMD display controller supporting the DLP5531-Q1 automotive exterior lighting chipset
  • Video processing
    • scales input image to match DMD resolution
    • Support for pixel doubling or quadrupling to allow low resolution video input – gamma correction
  • Embedded processor with error correction ( ECC )
    • On-chip diagnostic and self-test capability
    • System diagnostics including temperature monitoring and device interface monitoring

The DLPC230-Q1 integrates an embedded processor with error code correction (SECDED ECC), enabling host control and real-time feedback, on-chip diagnostics, and system monitoring functions. On-chip SRAM is included to get rid of the need for external DRAM. Sub-LVDS 600-MHz DMD interface allows high DMD refresh rates to generate seamless and brilliant digital images and smooth illumination profiles, while simultaneously reducing radiated emissions.

TPS99000-Q1 System Management and Illumination Controller

  • AEC-Q100 qualified with the following results
    • Temperature grade 2: -40°C to 105°C ambient operating temperature
    • Device HBM ESD classification level 2
    • Device CDM ESD classification level C4B
  • Automotive system management device for DLP products:
    • Advanced power monitoring, sequencing, and protection circuits
    • Two die temperature monitors, MCU external watchdog timer, clock frequency monitor
    • SPI port with parity, checksum, and password register protection
    • Second SPI port for independent system monitoring
  • On-chip DMD mirror voltage regulators
    • Generates +16-V, +8.5-V and -10-V DMD control voltages

The TPS99000-Q1 system management and illumination controller is part of the DLP5531-Q1 chipset, which also includes the DLPC230-Q1 DMD display controller. A built-in DMD high-voltage regulator supplies DMD mirror reference voltages, meeting the necessary tight tolerances. The ability supply sequencer and monitor provide robust coordination of power-up and power-down events for the whole chipset. The TPS99000-Q1 illumination controller integrates a 12-bit ADC. The ADC is capable of automatic sampling up to 63 events per video frame. Advanced system status monitoring circuits provide real-time visibility into display sub-system operational condition, including two processor watchdog circuits, two die temperature monitors, comprehensive supply monitoring for overvoltage and undervoltage detection, checksum and password register protection with byte-level parity on SPI bus transactions, along with other built-in test functions.

System Design Theory

The chipset consists of three components-the DLP5531-Q1 automotive DMD, the DLPC230-Q1, and also the TPS99000-Q1. The DMD is a light modulator consisting of tiny mirrors which are accustomed to form and project images. The DLPC230-Q1 is really a controller for the DMD; it formats incoming video and controls the timing of the DMD illumination sources and the DMD to be able to display the incoming video. The TPS99000-Q1 is really a high performance voltage regulator for that DMD along with a management IC for the whole chipset. Together, the DLPC230-Q1 and the TPS99000-Q1 can be used as system-level monitoring, diagnostics, and failure detection features.

Components Overview

The TID-080007 DLP Products Headlight Reference Design uses the DLPC230-Q1, TPS99000-Q1, and also the DLP5531-Q1 automotive DMD to allow a headlight projection system with unprecedented resolution and grayscale light control. The chipset manages the illumination control of LED sources, power sequencing functions, and system management functions. The chipset supports numerous system diagnostic and built-in self-test (BIST) features.

The DLP5531-Q1 DMD is a micro-electro-mechanical system (MEMS) device that receives electrical signals being an input (video data), and creates a mechanical output (mirror position). The electrical interface to the DMD is really a sub-LVDS interface using the DLPC230-Q1. The mechanical output may be the state of more than 1.3 million mirrors in the DMD array. Each mirror can be tilted ±12°. By manipulating the state from the mirrors designers are able to digitally control the light distribution of the headlight.

The DLPC230-Q1 is a controller for that DMD and the light sources in the DLP headlight module. It receives input video in the host and synchronizes DMD and light source timing in order to achieve the desired light distribution on the road. Since the DMD can only display binary patterns the DLPC230 must process incoming video data and convert it to the native DMD format. The DLPC230 then synchronizes the data shown on the DMD with source of light timing to create a video with grayscale shading. The DLPC230-Q1 sends drive enable signals towards the LED or laser driver. The control signals towards the DMD are sent using a sub-LVDS interface. The sub-LVDS interface is continuously monitored using a high-speed training routine that is used to optimize the interface timing as well as detect potential errors around the interface.

Control commands from the host could be delivered to the DLPC230-Q1 via I2C or SPI. The bus that isn't being used for host commands can be used a read-only bus for diagnostic purposes. Within this design, the SPI bus can be used for the command interface and also the I2C bus is used with diagnostic memory. Input video could be sent over an OpenLDI bus or a 24-bit parallel bus. The 24-bit bus can be limited to only 8bits of data for single light source systems such as headlights. For external video input this design uses the OpenLDI bus.

The SPI flash memory connected to the DLPC230-Q1 stores the default system settings and embedded software for that DLPC230-Q1's ARM core. The SPI flash memory can be written through the DLPC230-Q1 bootloader application that is stored in the DLPC230-Q1 ROM.

The TMP411 uses an I2C interface to supply the DMD array temperature towards the DLPC230-Q1. The outputs of the DLPC230-Q1 are configuration and monitoring commands to the TPS99000-Q1, timing controls towards the LED or laser driver, control and data signals to the DMD, and monitoring and diagnostics information to the host processor.

The TPS99000-Q1 provides diagnostic and monitoring information to the DLPC230-Q1 using an SPI bus and several other control signals such as PARKZ, INTZ, and RESETZ to manage power-up and powerdown sequencing. The TPS99000-Q1 is really a highly integrated mixed-signal IC that controls DMD power and offers monitoring and diagnostics information for the DLP headlight module. The DLPC230-Q1 communicates with the TPS99000-Q1 over an SPI bus. It uses this to configure the TPS99000-Q1 and also to read monitoring and diagnostics information in the TPS99000-Q1.

The power sequencing and monitoring blocks of the TPS99000-Q1 properly switch on the DMD and provide accurate DMD voltage rails ( -16 V, 8.5 V, and 10 V), after which monitor the system's power rails during operation. The combination of those functions into one IC significantly reduces design time and complexity versus utilizing a discrete solution. The TPS99000-Q1 receives inputs in the DLPC230-Q1, the power rails it monitors, and also the host processor. The DLPC230-Q1's clocks will also be monitored through the watchdogs within the TPS99000-Q1 to detect errors within the DLPC230-Q1 hardware or even the embedded software. The ability rails are monitored by the TPS99000-Q1 to be able to detect power failures or glitches and request a proper power down and parking of the DMD mirrors in case of a mistake. The host processor can see diagnostics information from the TPS99000-Q1 utilizing a dedicated SPI bus, which helps independent monitoring. Additionally the host can request the image to be switched on or off using a PROJ_ON signal. Lastly, the TPS99000-Q1 has lots of general-purpose ADCs you can use to apply system level monitoring functions. The outputs from the TPS99000-Q1 are diagnostic information and error alerts to the DLPC230-Q1. In the event of critical system errors, for example power loss, it outputs signals to the DLPC230-Q1 that trigger turn off or reset sequences.

Hardware, Software, Testing Requirements, and Test Results

Required Hardware and Software

Hardware

To test the functionality of the TIDA-080007 board simply connect the board to some 12V 1A power via J1. Capabilities can be tested by connecting an OpenLDI video source to J6. This PCB is made to drive enable signals to an LED source like the LED driver found in the DLP5531-Q1 EVM. Begin to see the DLP5531-Q1 Electronics Evaluation Module User’s Guide for additional details. TIDA-080007 is also mechanically just like the DLP5531-Q1 EVM and thus works with any optical reference designs which are created for that EVM.

Software

To get started with the TIDA-080007 hardware, the flash must be programmed using the following steps:

  • Connect a Cheetah SPI adapter (Cheetah SPI Host Adapter) to J2 and connect the SPI adapter to some PC running MS Windows 7 or higher.
  • Connect an energy supply to J1 to turn on the device.
  • Connect to the TIDA-080007 board while using DLPC230 Control Program.
  • Click the Connect The green circle should then light up to point that connection was successful towards the Cheetah Adapter.
  • To connect, set the DLPC230-Q1 “Host” to SPI and choose the Cheetah device from the drop-down menu.

Figure 3. Programming the TIDA-080007 Flash Memory While using DLPC230 Control Program

Testing and Results

System Test Setup

In to test the unit power was supplied by a 12 V lab power supply, Video input over OpenLDI (LVDS) was supplied by an Astro VG-870B video generator. Communication over SPI was supplied by a Cheetah USB to SPI adapter with the DLPC230 Control Program.

System Test Results

Video display

To test the input, an Astro VG-870 with LVDS card was used to output an 1152 x 576 image at 60 Hz. During the test, a picture was displayed correctly around the DMD with no system errors were reported.

Shutdown on power loss

To assure reliable operation, the DMD must properly turn off and park the mirrors throughout a brownout condition. The machine must have enough endure capacitance to power the DLPC230-Q1, TPS99000-Q1, and DLP5531-Q1 until the park procedure is complete. The park timing is described in the TPS99000 data sheet. Power loss detection is tripped when the voltage around the VMAIN monitor of the TPS99000 falls below 1.35 volts. There is a 4 times voltage divider on the VMAIN pin therefore the shutdown signal happens at 5.4 V. The system was tested at nominal conditions of 12 V input voltage and 25C ambient operating temperature. Figure 6 shows the endure time from when the input voltage monitor trips to once the 3.3 V regulator stops regulating. This exceeds the data sheet timing requirement.

EMC Test Setup

Limited EMC pre-compliance testing was done at a third-party accredited lab. Testing was performed while displaying video test patterns from the DLPC230 internal pattern generator with spread spectrum enabled. This design showed acceptable results, meeting the requirements for CISPR 25 Class 5 in some instances, CISPR 25 Class 3 radiated emissions in most cases and CISPR 25 Class 1 radiated emissions overall. It's recommenced that pre-compliance testing begins at an early stage within the design process especially if targeting tighter CISPR 25 Class 5 or OEM specific EMC requirements. Results from the EMC testing are supplied below. All graphs are shown with the CISPR 25 Class 3 limits. Only the graphs are provided in this report. Tables might be provided upon request.

Figure 7 shows the exam setup utilizing a biconical antenna for the 30MHz to 200MHz range.

Figure 8 shows the exam setup for conducted emissions with the LISNs (line impedance stabilization network) connections shown on the left side, those are the grey boxes.

EMC Test Results

Conducted Emissions

In Figure 9, emissions from 150kHz to approximately 26MHz meet CISPR 25 Class 3 conducted emissions. At approximately 26MHz emissions meet Class 1 conducted emissions. At approximately 80MHz, emissions meet Class 1 conducted emissions. Only the measurement from the positive lead is shown because it is nearly identical to the return (ground) lead.

Radiated Emissions

From 200kHz to 30MHz, emissions meet CISPR 25 Class 3 limits. From 30MHz to 200MHz, emissions meet CISPR 25 Class 3 limits aside from at approximately 145MHz where emissions still meet CISPR 25 Class 1 limits. Beyond 200MHz, emissions meet CISPR 25 Class 5 limits.