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

7.3.9.3 LED Short-to-GND Detection

The TPS92633-Q1 device has LED short-to-GND detection. The LED short-to-GND detection monitors the output voltage when the output current is enabled. Once a short-to-GND LED failure is detected, the device turns off the faulty channel and retries automatically, regardless of the state of the PWM input. When the retry mechanism detects the removal of the LED short-to-GND fault, the device resumes to normal operation.

The TPS92633-Q1 monitors the V(OUTx) voltage and V(RESx) voltage of each channel and compares it with the internal reference voltage to detect a short-to-GND failure. When V(OUTx) or V(RESx) voltage falls below V(SG_th_falling) longer than the deglitch time of t(SG_deg), the device asserts the short-to-GND fault and pulls low the FAULT pin. During the deglitch time period, if V(OUTx) and V(RESx) rises above V(SG_th_rising), the timer is reset.

Once the TPS92633-Q1 has asserted a short-to-GND fault, the device turns off the faulty output channel and retries automatically with a small current. During retrying the device sources a small current I(Retry) from SUPPLY to OUT to pull up the LED loads continuously. Once auto-retry detects output voltage rising above V(SG_th_rising), it clears the short-to-GND fault and resumes to normal operation. Figure 7-7 illustrates the timing for LED short-circuit detection, protection, retry and recovery.

GUID-20201027-CA0I-NHSS-6T1T-NXTBDSBXGHQL-low.gif Figure 7-7 LED Short-to-GND Detection and Recovery Timing Diagram

The detailed information and value of each time period in Figure 7-7 is described in Timing Requirements.