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

7.3.1 Adaptive Off-Time Current Mode Control

The LP8865C-Q1 family adopts an adaptive off-time current mode control to support fast transient response over a wide range of operation. The switching frequency is set at 400kHz.

For average output current regulation, the sensed voltage across the sensing resistor between the CSP and CSN pins is compared with the internal voltage reference, VREF , through the error amplifier. The output of the error amplifier, VCOMP, passes through an external compensation network and is then compared with the peak current feedback at the PWM comparator. During each switching cycle, when the internal NMOS FET is turned on, the peak current is sensed through the internal FET. When the sensed value of peak current reaches VCOMP at the input of PWM comparator, the NMOS FET is turned off and the adaptive off-time counter starts counting. Once the adaptive off-time counter stops counting, the counter is reset until when the NMOS FET stays off. The counting off time is determined by the external resistor connected to the FSET pin and the input/output feed forward. Thus, the device is able to maintain a nearly constant switching frequency at steady state and regulate the output average current at a desired value.

LP8865C-Q1 Adaptive Off-Time Current Mode Control MethodFigure 7-1 Adaptive Off-Time Current Mode Control Method