SNVSCC4A October   2023  – September 2024 LP5811

PRODUCTION DATA  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Device Comparison
  6. Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Typical Characteristics
  7. Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Synchronous Boost Converter
        1. 6.3.1.1 Undervoltage Lockout
        2. 6.3.1.2 Enable and Soft Start
        3. 6.3.1.3 Switching Frequency
        4. 6.3.1.4 Current Limit Operation
        5. 6.3.1.5 Boost PWM Mode
        6. 6.3.1.6 Boost PFM Mode
      2. 6.3.2 Analog Dimming
      3. 6.3.3 PWM Dimming
      4. 6.3.4 Autonomous Animation Engine Control
        1. 6.3.4.1 Animation Engine Pattern
        2. 6.3.4.2 Sloper
        3. 6.3.4.3 Animation Engine Unit (AEU)
        4. 6.3.4.4 Animation Pause Unit (APU)
      5. 6.3.5 Protections and Diagnostics
        1. 6.3.5.1 Overvoltage Protection
        2. 6.3.5.2 Output Short-to-Ground Protection
        3. 6.3.5.3 LED Open Detections
        4. 6.3.5.4 LED Short Detections
        5. 6.3.5.5 Thermal Shutdown
    4. 6.4 Device Functional Modes
    5. 6.5 Programming
    6. 6.6 Register Maps
  8. Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Application
      2. 7.2.2 Design Parameters
      3. 7.2.3 Detailed Design Procedure
        1. 7.2.3.1 Inductor Selection
        2. 7.2.3.2 Output Capacitor Selection
        3. 7.2.3.3 Input Capacitor Selection
        4. 7.2.3.4 Program Procedure
        5. 7.2.3.5 Programming Example
      4. 7.2.4 Application Performance Plots
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. Device and Documentation Support
    1. 8.1 Documentation Support
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

PWM Dimming

The LP5811 supports 8-bit PWM dimming with 24kHz or 12kHz frequency, which is configured by 'PWM_Fre' bit in Dev_config_1 register. An internal 6MHz oscillator is used to generate the PWM clock. SYNC pin can be configured as PWM clock input or output by configure 'vsync_out_en' bit in Dev_Config_11 register. If multiple LP5811 are used in the system with autonomous animation engine control, all devices can refer the same clock signal, which comes from one of LP5811 or external controller, to avoid animation mismatch in long time operation.

Each LED can be configured into 3 different PWM alignment phases: Forward, Middle, and Backward. The alignment phase of each LED is set by 'phase_align' bits in Dev_Config_7 to Dev_Config_10 registers. By turning on the LEDs in different phase, the peak current load from boost or the system power supply is greatly decreased. The input current ripple and ceramic-capacitor audible ringing can also be reduced. Figure 6-3 shows the PWM alignment phases. In the forward alignment, the rising edge of PWM pulse is fixed at the beginning of PWM period. In the middle alignment, the middle point of PWM pulse is fixed at the middle of PWM period, while the pulse spreads to both directions. In the backward alignment, the falling edge of PWM pulse is fixed at the end of PWM period.

LP5811 PWM Alignment Scheme Figure 6-3 PWM Alignment Scheme

The LP5811 allow users to configure the dimming scale as exponential curve or linear curve, through the ‘exp_en’ bits in Dev_Config_5 and Dev_Config_6 registers. A human-eye-friendly visual performance can be achieved by using the internal exponential scale. The linear scale has great linearity between PWM duty cycle and PWM setting value, which provides flexible approach for external controlled gamma correction algorithm. The 8-bit linear and exponential curves are shown as Figure 6-4.

LP5811 Linear and Exponential PWM
                    Dimming Curves Figure 6-4 Linear and Exponential PWM Dimming Curves