DLPS039F December   2015  – April 2019 TPS99000-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Typical Standalone System
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions - Initialization, Clock, and Diagnostics
    2.     Pin Functions - Power and Ground
    3.     Pin Functions - Power Supply Management
    4.     Pin Functions - Illumination Control
    5.     Pin Functions - Serial Peripheral Interfaces
    6.     Pin Functions - Analog to Digital Converter
  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 - Transimpedance Amplifier Parameters
    6. 6.6  Electrical Characteristics - Digital to Analog Converters
    7. 6.7  Electrical Characteristics - Analog to Digital Converter
    8. 6.8  Electrical Characteristics - FET Gate Drivers
    9. 6.9  Electrical Characteristics - Photo Comparator
    10. 6.10 Electrical Characteristics - Voltage Regulators
    11. 6.11 Electrical Characteristics - Temperature and Voltage Monitors
    12. 6.12 Electrical Characteristics - Current Consumption
    13. 6.13 Power-Up Timing Requirements
    14. 6.14 Power-Down Timing Requirements
    15. 6.15 Timing Requirements - Sequencer Clock
    16. 6.16 Timing Requirements - Host / Diagnostic Port SPI Interface
    17. 6.17 Timing Requirements - ADC Interface
    18. 6.18 Switching Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Illumination Control
        1. 7.3.1.1 Illumination System High Dynamic Range Dimming Overview
        2. 7.3.1.2 Illumination Control Loop
        3. 7.3.1.3 Continuous Mode Operation
          1. 7.3.1.3.1 Output Capacitance in Continuous Mode
          2. 7.3.1.3.2 Continuous Mode Driver Distortion and Blanking Current
          3. 7.3.1.3.3 Continuous Mode S_EN2 Dissipative Load Shunt Options
          4. 7.3.1.3.4 Continuous Mode Constant OFF Time
          5. 7.3.1.3.5 Continuous Mode Current Limit
        4. 7.3.1.4 Discontinuous Mode Operation
          1. 7.3.1.4.1 Discontinuous Mode Pulse Width Limit
          2. 7.3.1.4.2 COMPOUT_LOW Timer in Discontinuous Operation
          3. 7.3.1.4.3 Dimming Within Discontinuous Operation Range
          4. 7.3.1.4.4 Multiple Pulse Heights to Increase Bit Depth
          5. 7.3.1.4.5 TIA Gain Adjustment
          6. 7.3.1.4.6 Current Limit in Discontinuous Mode
          7. 7.3.1.4.7 CMODE Big Cap Mode in Discontinuous Operation
      2. 7.3.2 Over-Brightness Detection
        1. 7.3.2.1 Photo Feedback Monitor BIST
        2. 7.3.2.2 Excessive Brightness BIST
      3. 7.3.3 Analog to Digital Converter
        1. 7.3.3.1 Analog to Digital Converter Input Table
      4. 7.3.4 Power Sequencing and Monitoring
        1. 7.3.4.1 Power Monitoring
      5. 7.3.5 DMD Mirror Voltage Regulator
      6. 7.3.6 Low Dropout Regulators
      7. 7.3.7 System Monitoring Features
        1. 7.3.7.1 Windowed Watchdog Circuits
        2. 7.3.7.2 Die Temperature Monitors
        3. 7.3.7.3 External Clock Ratio Monitor
      8. 7.3.8 Communication Ports
        1. 7.3.8.1 Serial Peripheral Interface (SPI)
    4. 7.4 Device Functional Modes
      1. 7.4.1 OFF
      2. 7.4.2 STANDBY
      3. 7.4.3 POWERING_DMD
      4. 7.4.4 DISPLAY_RDY
      5. 7.4.5 DISPLAY_ON
      6. 7.4.6 PARKING
      7. 7.4.7 SHUTDOWN
    5. 7.5 Register Maps
      1. 7.5.1 System Status Registers
      2. 7.5.2 ADC Control
      3. 7.5.3 General Fault Status
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 HUD
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Application Design Considerations
          1. 8.2.1.2.1 Photodiode Considerations
          2. 8.2.1.2.2 LED Current Measurement
          3. 8.2.1.2.3 Setting the Current Limit
          4. 8.2.1.2.4 Input Voltage Variation Impact
          5. 8.2.1.2.5 Discontinuous Mode Photo Feedback Considerations
          6. 8.2.1.2.6 Transimpedance Amplifiers (TIAs, Usage, Offset, Dark Current, Ranges, RGB Trim)
      2. 8.2.2 Headlight
        1. 8.2.2.1 Design Requirements
  9. 9 Power Supply Recommendations
    1. 9.1 TPS99000-Q1 Power Supply Architecture
    2. 9.2 TPS99000-Q1 Power Outputs
    3. 9.3 Power Supply Architecture
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Power/High Current Signals
      2. 10.1.2 Sensitive Analog Signals
      3. 10.1.3 High Speed Digital Signals
      4. 10.1.4 High Power Current Loops
      5. 10.1.5 Kelvin Sensing Connections
      6. 10.1.6 Ground Separation
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information
    1. 12.1 Package Option Addendum
      1. 12.1.1 Tape and Reel Information
      2. 12.1.2 Mechanical Drawings

Package Options

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

7.3.1.3.5 Continuous Mode Current Limit

In continuous mode, a current limit feature prevents damage to LEDs if the requested light output cannot be achieved within LED current specifications. This could happen due to high temperature, or when an LED ages and requires more current to achieve the same brightness. Systems should be designed with sufficient thermal and LED life time margin that this would not happen in practice.

The control scheme utilizes the built in current limit feature of the LM3409 device plus a 10-bit DAC based adjustment feature included in the TPS99000-Q1. This serves as an alternate limit for the current for the LEDs – inductor drive will be disabled if either the current limit is met or if the photo feedback limit is met, whichever is lower. This peak current limit is configurable on a per LED basis, and is in use during the light-on active periods only. (During blanking periods, this same structure is used to control the blanking current, but different values are loaded onto the ILIM DAC).

The schematic for the current adjustment mechanism is shown in Figure 19.

TPS99000-Q1 IADJ_peak_curnt_limit_detail_DLPS039.gifFigure 19. IADJ Peak Current Limit Schematic

By design, the LM3409 seeks to create a zero voltage difference between the CSP and CSN pins when IADJ pin is held low and system is operating in peak current limit mode. If the CSP pin voltage is higher than the CSN pin voltage, the PGATE driver is held high (PFET off).

When the ILIM DAC is set to a non-zero voltage, a current is established on the IADJ line of the TPS99000-Q1 device, which pulls the voltage of the CSP pin downward. If the LM3409 device is enabled and PFET drive not held off by state of the COFF pin, then the current will go up until the voltage across the sense resistor is such that the CSN pin is equal to or greater than the voltage on the CSP pin, at which point the PFET is turned off.

Care must be taken with the routing of the IADJ pin of the TPS99000-Q1 to insure that it is well isolated from noisy switching nodes, such as the PFET drain node.