SLVSF65A December   2020  – May 2021 TPS92633-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  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
    6. 6.6 Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Power Supply (SUPPLY)
        1. 7.3.1.1 Power-On Reset
        2. 7.3.1.2 Supply Current in Fault Mode
      2. 7.3.2  Enable and Shutdown (EN)
      3. 7.3.3  Reference Current (IREF)
      4. 7.3.4  Constant-Current Output and Setting (INx)
      5. 7.3.5  Analog Current Control (ICTRL)
        1. 7.3.5.1 Off-Board Brightness Binning Resistor
        2. 7.3.5.2 NTC Resistor
      6. 7.3.6  Thermal Sharing Resistor (OUTx and RESx)
      7. 7.3.7  PWM Control (PWMx)
      8. 7.3.8  Supply Control
      9. 7.3.9  Diagnostics
        1. 7.3.9.1 IREF Short-to-GND Detection
        2. 7.3.9.2 IREF Open Detection
        3. 7.3.9.3 LED Short-to-GND Detection
        4. 7.3.9.4 LED Open-Circuit Detection
        5. 7.3.9.5 Single LED Short-Circuit Detection (SLS_REF)
        6. 7.3.9.6 LED Open-Circuit and Single LED Short-Circuit Detection Enable (DIAGEN)
        7. 7.3.9.7 Low Dropout Operation
        8. 7.3.9.8 Over-Temperature Protection
      10. 7.3.10 FAULT Bus Output With One-Fails–All-Fail
      11. 7.3.11 FAULT Table
      12. 7.3.12 LED Fault Summary
      13. 7.3.13 IO Pins Inner Connection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Undervoltage Lockout, V(SUPPLY) < V(POR_rising)
      2. 7.4.2 Normal Operation V(SUPPLY) ≥ 4.5 V
      3. 7.4.3 Low-Voltage Dropout Operation
      4. 7.4.4 Fault Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 BCM Controlled Rear Lamp with One-Fails-All-Fail Setup
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Independent PWM Controlled Rear Lamp with Off Board LED and Binning Resistor
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
        3. 8.2.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

7.3.5.2 NTC Resistor

The analog current control feature also allows to connect a NTC thermistor on ICTRL pin to achieve the LED current derating based on measured PCB board temperature or LED unit temperature. The resistance of NTC thermistor depends on the environment temperature. The resistance of NTC thermistor is decreasing with the temperature rising. It leads to the decreasing of the equivalent resistance of R(ICTRL) on ICTRL pin and the output current reduction from the calculation based on Equation 2 and Equation 3.

TI recommends to connect a resistor network including NTC thermistor (e.g. NCU18XH103F6SRB) to ICTRL pin as illustrated in below Figure 7-2. The resistor value of R1 and R2 work with NTC thermistor to adjust the equivalent resistance curve depending on the temperature to achieve the system required current derating.

GUID-807B9ED6-3150-4654-83A1-EE2C4A08781E-low.gif Figure 7-2 Application Schematic For External NTC Thermistor