SNVSCV5 October   2025 TPS923621 , TPS923622

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Enable and Start-up
      2. 7.3.2 Under-Voltage Lockout (UVLO)
      3. 7.3.3 Shutdown
      4. 7.3.4 Boost Control Operation
      5. 7.3.5 Switching Peak Current Limit
      6. 7.3.6 Over-Voltage Protection
      7. 7.3.7 Output Current Setting
      8. 7.3.8 Output Current PWM Controlled Analog Dimming
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation Mode
      2. 7.4.2 Over-Voltage Protection Mode
      3. 7.4.3 Shutdown Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Inductor Selection
        2. 8.2.2.2 Schottky Diode Selection
        3. 8.2.2.3 Output Capacitor Selection
        4. 8.2.2.4 LED Current Set Resistor
        5. 8.2.2.5 Thermal Considerations
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.3.7 Output Current Setting

The FB voltage is regulated to a 200mV reference voltage. The LED current is set externally using a current-sense resistor in series with the LED strings. The value of the RSET (R3 on EVM) is calculated using:

Equation 1. IOUT=VFBRSET

where

  • ILED = total output current of LED strings
  • VFB = regulated voltage of FB pin
  • RSET = current sense resistor

The output current tolerance depends on the FB accuracy and the current sensor resistor accuracy.

R2 is optional resistor paralleled with R3 to fine tune the RSET to target value, or used to balance the total power loss on RSET.