SLVSC76E February   2014  – May 2018 TPS92630-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Typical Application Schematic
  5. 5 Revision History
  6. 6 Description (Continued)
  7. 7 Pin Configuration and Functions
    1.     Pin Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 ESD Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Timing Requirements
    7. 8.7 Typical Characteristics
  9. 9 Parameter Measurement Information
  10. 10Detailed Description
    1. 10.1 Overview
    2. 10.2 Functional Block Diagram
    3. 10.3 Feature Description
      1. 10.3.1 Constant LED-Current Setting
      2. 10.3.2 PWM Control
      3. 10.3.3 FAULT Diagnostics
      4. 10.3.4 Short-Circuit Detection
      5. 10.3.5 Open-Load Detection
      6. 10.3.6 Thermal Foldback
    4. 10.4 Device Functional Modes
      1. 10.4.1 Thermal Information
      2. 10.4.2 Operation With V(VIN) < 5 V (Minimum V(VIN))
      3. 10.4.3 Operation With 5 V < V(VIN) < 9 V (Lower-Than-Normal Automotive Battery Voltage)
  11. 11Applications and Implementation
    1. 11.1 Application Information
    2. 11.2 Typical Applications
      1. 11.2.1 Stoplight and Taillight Application With PWM Generator
        1. 11.2.1.1 Design Requirements
        2. 11.2.1.2 Detailed Design Procedure
          1. 11.2.1.2.1 Step-by-Step Design Procedure
            1. 11.2.1.2.1.1 R(REF)
            2. 11.2.1.2.1.2 Duty Cycle
            3. 11.2.1.2.1.3 Input and Output Capacitors
        3. 11.2.1.3 PWM Dimming Application Curve
      2. 11.2.2 Simple Stop-Light and Taillight Application
        1. 11.2.2.1 Design Requirements
        2. 11.2.2.2 Detailed Design Procedure
          1. 11.2.2.2.1 Step-by-Step Design Procedure
            1. 11.2.2.2.1.1 R(REF)
            2. 11.2.2.2.1.2 R(Stop)
            3. 11.2.2.2.1.3 Input and Output Capacitors
      3. 11.2.3 Parallel Connection
        1. 11.2.3.1 Design Requirements
        2. 11.2.3.2 Detailed Design Procedure
          1. 11.2.3.2.1 Step-by-Step Design Procedure
            1. 11.2.3.2.1.1 R(REF)
            2. 11.2.3.2.1.2 Input and Output Capacitors
      4. 11.2.4 Alternate Parallel Connection
        1. 11.2.4.1 Design Requirements
        2. 11.2.4.2 Detailed Design Procedure
          1. 11.2.4.2.1 Step-by-Step Design Procedure
            1. 11.2.4.2.1.1 R(REF)
            2. 11.2.4.2.1.2 Input and Output Capacitors
      5. 11.2.5 High-Side PWM Dimming
        1. 11.2.5.1 Design Requirements
        2. 11.2.5.2 Detailed Design Procedure
          1. 11.2.5.2.1 Step-by-Step Design Procedure
            1. 11.2.5.2.1.1 Ratio of Resistors, R1 / R2
            2. 11.2.5.2.1.2 R1 and R2 Selection
            3. 11.2.5.2.1.3 Input and Output Capacitors
  12. 12Power Supply Recommendations
  13. 13Layout
    1. 13.1 Layout Guidelines
    2. 13.2 Layout Example
  14. 14Device and Documentation Support
    1. 14.1 Documentation Support
      1. 14.1.1 Related Documentation
    2. 14.2 Receiving Notification of Documentation Updates
    3. 14.3 Community Resources
    4. 14.4 Trademarks
    5. 14.5 Electrostatic Discharge Caution
    6. 14.6 Glossary
  15. 15Mechanical, Packaging, and Orderable Information

11.2.1 Stoplight and Taillight Application With PWM Generator

Another easy way to achieve the different brightness is dimming by pulse-width modulation (PWM), which holds the color spectrum of the LED over the whole brightness range. The maximum current that passes through the LED is programmable by sense resistor RREF.

Figure 26 shows the application circuit of the stoplight and taillight including an automotive-qualified timer, TLC555-Q1, the duty cycle of which is programmable by two external resistors. One can see that driving the STOP signal high pulls the PWM pin constantly high, creating 100% duty cycle. Thus the LEDs operate at full brightness. When the TAIL signal is high, the LEDs operate at 50% brightness because the TLC555-Q1 timer is programmed at a fixed duty cycle of 50%.

TPS92630-Q1 app_sec2_SLVSC76.gifFigure 26. Two-Level Brightness Adjustment Using the TPS92630-Q1 With PWM