SNVSCE3B May   2023  – November 2023 LP5866T

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 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 Time-Multiplexing Matrix
      2. 7.3.2 Analog Dimming (Current Gain Control)
        1. 7.3.2.1 Global 3-Bits Maximum Current (MC) Setting
        2. 7.3.2.2 3 Groups of 7-Bits Color Current (CC) Setting
        3. 7.3.2.3 Individual 8-bit Dot Current (DC) Setting
      3. 7.3.3 PWM Dimming
        1. 7.3.3.1 Individual 8-Bit / 16-Bit PWM for Each LED Dot
        2. 7.3.3.2 Programmable Groups of 8-Bit PWM Dimming
        3. 7.3.3.3 8-Bit PWM for Global Dimming
      4. 7.3.4 ON and OFF Control
      5. 7.3.5 Data Refresh Mode
      6. 7.3.6 Full Addressable SRAM
      7. 7.3.7 Protections and Diagnostics
        1. 7.3.7.1 LED Open Detection
        2. 7.3.7.2 LED Short Detection
        3. 7.3.7.3 Thermal Shutdown
        4. 7.3.7.4 UVLO (Under Voltage Lock Out)
    4. 7.4 Device Functional Modes
    5. 7.5 Programming
      1. 7.5.1 Interface Selection
      2. 7.5.2 I2C Interface
        1. 7.5.2.1 I2C Data Transactions
        2. 7.5.2.2 I2C Data Format
        3. 7.5.2.3 Multiple Devices Connection
      3. 7.5.3 Programming
        1. 7.5.3.1 SPI Data Transactions
        2. 7.5.3.2 SPI Data Format
        3. 7.5.3.3 Multiple Devices Connection
    6. 7.6 Register Maps
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Application
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Program Procedure
      4. 8.2.4 Application Performance Plots
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 VDD Input Supply Recommendations
      2. 8.3.2 VLED Input Supply Recommendations
      3. 8.3.3 VIO Input 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 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.7.2 LED Short Detection

The LP5866T includes LED short detection (LSD) for the fault caused by any shorted LED. Threshold for channel short is (VLED – 1) V typical. LED short detection only performed when PWM ≥ 25 (Mode 1 and Mode 2) or PWM ≥ 6400 (Mode 3) and voltage on CSn is detected higher than short threshold for continuously 4 sub-periods. As there is parasitic capacitance for the current sink, to make sure the LSD result is correct, setting the LED current higher than 0.5mA is recommended.

The image below shows the detection circuit of LSD function. When short fault is detected, 'Global_LSD bit' in Fault_state register is set to 1 and detailed fault state for every channel are also monitored in register Dot_lsdx (x = 0, 1, … , 17). All short fault indicator bits can be cleared by setting LSD_clear = 0Fh after the short condition is removed.

LSD removal function can be enabled by setting 'LSD_removal' bit in Dev_config2 register to 1. This function turns off the upside deghosting function of the scan line where short LED is included.

LP5866T LSD CircuitFigure 7-12 LSD Circuit