SLVSIQ0 May   2025 LP8865C-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4  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 Adaptive Off-Time Current Mode Control
      2. 7.3.2 Setting LED Current
      3. 7.3.3 Internal Soft Start
      4. 7.3.4 Dimming Mode
        1. 7.3.4.1 PWM dimming
        2. 7.3.4.2 Analog dimming
      5. 7.3.5 Fault Protection
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 LP8865CUQDGNRQ1 12V Input, 1A Output, 8-piece WLED Driver With Analog Dimming
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selection
          2. 8.2.1.2.2 Input Capacitor Selection
          3. 8.2.1.2.3 Output Capacitor Selection
          4. 8.2.1.2.4 Sense Resistor Selection
          5. 8.2.1.2.5 Other External Components Selection
      2. 8.2.2 LP8865CYQDGNRQ1 24V Input, 0.5A Output, 4-piece WLED Driver With PWM Dimming
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Inductor Selection
          2. 8.2.2.2.2 Input Capacitor Selection
          3. 8.2.2.2.3 Output Capacitor Selection
          4. 8.2.2.2.4 Sense Resistor Selection
          5. 8.2.2.2.5 Other External Components Selection
      3. 8.2.3 LP8865CWQDGNRQ1 24V Input, 2A Output, 4-piece WLED Driver With Analog Dimming
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
          1. 8.2.3.2.1 Inductor Selection
          2. 8.2.3.2.2 Input Capacitor Selection
          3. 8.2.3.2.3 Output Capacitor Selection
          4. 8.2.3.2.4 Sense Resistor Selection
          5. 8.2.3.2.5 Other External Components Selection
    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 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
8.2.2.2.4 Sense Resistor Selection

The maximum LED current is 0.5A at 100% PWM duty and the corresponding VREF is 200mV. By using Equation 33, the sense resistance is calculated as 400mΩ. Note that the power consumption of the sense resistor is 100mW, requiring enough margin of the resistor's power rating in selection.

Equation 22. RSENSE=VREFILED_FS

In this design, a 100Ω resistor is recommended for RFLT at CSN pin to avoid noise injection and increase robustness. An optional 1nF, 50V X7R ceramic capacitor is chosen for CFLT across CSP-CSN pins to filter high-frequency noise of sense feedback. Using the equation below, a 2.2μF, 50V X7R ceramic capacitor is chosen for CSNS to suppress the ac magnitude of sense feedback less than 200mV.

Equation 23. CSENSE=  0.25×IL(max)200mV×fSW