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 Analog Current Control (ICTRL)

The TPS92633-Q1 supports analog constant current control for all three output channels together through adjusting the V(CS_REG) voltage. As described in Constant-Current Output and Setting (INx), the TPS92633-Q1 regulates each channel output current by maintaining the voltage drop on each R(SNSx) same to V(CS_REG). The V(CS_REG) voltage is adjustable by an external resistor on ICTRL pin. The TPS92633-Q1 outputs a constant current, I(ICTRL), on the ICTRL pin and measures the voltage on the ICTRL pin, V(ICTRL), to determine the V(CS_REG). The I(ICTRL) current is 10 times of the I(IREF), and the V(ICTRL) is multiplied result of I(ICTRL) and R(ICTRL). The TPS92633-Q1 internally clamps the V(ICTRL) to maximum 2.75 V. The V(CS_REG) voltage can be calculated by using Equation 3.

Equation 3. GUID-C4E94C8D-E3D2-4E25-9950-3F272304592F-low.gif

where

  • I(IREF) is in A unit
  • R(ICTRL) is in Ω unit
  • V(CS_REG) is in V unit

The minimum voltage of V(CS_REF) is 50 mV typically to maintain the high accurate current output.

The final total output current for each channel can be calculated by using Equation 4 which is combination of Equation 1, Equation 2 and Equation 3.

Equation 4. GUID-ADF0E45E-82E8-4250-8F69-7C7FFB672333-low.gif

where

  • V(IREF) = 1.235 V
  • R(IREF) is in kΩ unit
  • R(ICTRL) is in Ω unit
  • R(SNSx) is in Ω unit
  • I(OUTx_Tot) is in mA unit

The calculated result for I(OUTx_Tot) is 147.7 mA when R(IREF) is 12.3 kΩ, R(ICTRL) is 1000 Ω and R(SNSx) is 1Ω.