DLPS039F December 2015 – April 2019 TPS99000-Q1
The DLPC230-Q1 is a controller for the DMD and the timing of the RGB LEDs in the HUD. It requests the proper timing and amplitude from the LEDs to achieve the requested color and brightness from the HUD across the entire operating range. It synchronizes the DMD with these LEDs in order to generate full-color video requested from the host.
The DLPC230-Q1 receives inputs from a host processor in the vehicle. The host provides commands and input video data. Read and write (R/W) commands can be sent using either the I2C bus or SPI bus. The bus that is not being used for R/W commands can be used as a read-only bus for diagnostic purposes. Input video can be sent over an OpenLDI bus or a parallel 24-bit bus. The SPI flash memory provides the embedded software for the DLPC230-Q1’s ARM core, color calibration data, and default settings. 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 power-down sequencing. The DLPC230-Q1 interfaces to a TPM411 via I2C for temperature information.
The outputs of the DLPC230-Q1 are LED drive information to the TPS99000-Q1, control signals to the DMD, and monitoring and diagnostics information to the host processor. Based on a host requested brightness and the operating temperature, the DLPC230-Q1 determines the proper timing and amplitudes for the LEDs. It passes this information to the TPS99000-Q1 using an SPI bus and several additional control signals such as D_EN, S_EN, and SEQ_START. It controls the DMD mirrors by sending data over a sub-LVDS bus. It can alert the host about any critical errors using a HOST_IRQ signal.
The TPS99000-Q1 is a highly-integrated mixed-signal IC that controls DMD power, the analog response of the LEDs, and provides monitoring and diagnostics information for the HUD system. The power sequencing and monitoring blocks of the TPS99000-Q1 properly power up the DMD and provide accurate DMD voltage rails, and then monitor the system’s power rails during operation. The integration of these functions into one IC significantly reduces design time and complexity. The highly accurate photodiode (PD) measurement system and the dimming controller block precisely control the LED response. This enables a DLP technology HUD to achieve a very high dimming range (> 5000:1) with accurate brightness and color across the temperature range of the system. Finally, the TPS99000-Q1 has several general-purpose ADCs that designers can use for system-level monitoring, such as over-brightness detection.
The TPS99000-Q1 receives inputs from the DLPC230-Q1, power rail voltages for monitoring, a photodiode that is used to measure LED response, the host processor, and potentially several other ADC ports. The DLPC230-Q1 sends commands to the TPS99000-Q1 over a SPI port and several other control signals. The TPS99000-Q1 includes watchdogs to monitor the DLPC230-Q1 and ensure that it is operating as expected. The power rails are monitored by the TPS99000-Q1 to detect power failures or glitches and request a proper power down of the DMD in case of an error. The photodiode’s current is measured and amplified using a transimpedance amplifier (TIA) within the TPS99000-Q1. The host processor can read diagnostics information from the TPS99000-Q1 using a dedicated SPI bus. Additionally the host can request the system to be turned on or off using a PROJ_ON signal. The TPS99000-Q1 has several general-purpose ADCs that can be used to implement other system features such as over-brightness and over-temperature detection.
The outputs of the TPS99000-Q1 are LED drive signals, diagnostic information, and error alerts to the DLPC230-Q1. The TPS99000-Q1 has signals connected to the LM3409 buck controller for high power LEDs and to discrete hardware that control the LEDs. The TPS99000-Q1 can output diagnostic information to the host and the DLPC230-Q1 over two SPI busses. It also has signals such as RESETZ, PARKZ, and INTZ that can be used to trigger power down or reset sequences.
The DMD is a micro-electro-mechanical system (MEMS) device that receives electrical signals as an input (video data) and produces a mechanical output (mirror position). The electrical interface to the DMD is a sub-LVDS interface driven with the DLPC230-Q1. The mechanical output is the state of more than 1.3 million mirrors in the DMD array that can be tilted ±12°. In a projection system, the mirrors are used as pixels in order to display an image.