SNVSA50C August   2015  – May 2017 LP8861-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics
    6. 7.6  Internal LDO Electrical Characteristics
    7. 7.7  Protection Electrical Characteristics
    8. 7.8  Power Line FET Control Electrical Characteristics
    9. 7.9  Current Sinks Electrical Characteristics
    10. 7.10 PWM Brightness Control Electrical Characteristics
    11. 7.11 Boost/SEPIC Converter Characteristics
    12. 7.12 Logic Interface Characteristics
    13. 7.13 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Integrated Boost/SEPIC Converter
      2. 8.3.2 Internal LDO
      3. 8.3.3 LED Current Sinks
        1. 8.3.3.1 Current Sink Configuration
        2. 8.3.3.2 Current Setting
        3. 8.3.3.3 Brightness Control
      4. 8.3.4 Power-Line FET Control
      5. 8.3.5 LED Current Dimming With External Temperature Sensor
      6. 8.3.6 Protection and Fault Detection
        1. 8.3.6.1 Adaptive Boost Control and Functionality of LED Fault Comparators
        2. 8.3.6.2 Overview of the Fault/Protection Schemes
    4. 8.4 Device Functional Modes
      1. 8.4.1 Device States
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Typical Application for 4 LED Strings
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Inductor Selection
          2. 9.2.1.2.2 Output Capacitor Selection
          3. 9.2.1.2.3 Input Capacitor Selection
          4. 9.2.1.2.4 LDO Output Capacitor
          5. 9.2.1.2.5 Diode
          6. 9.2.1.2.6 Power Line Transistor
          7. 9.2.1.2.7 Input Current Sense Resistor
        3. 9.2.1.3 Application Curves
      2. 9.2.2 High Output Current Application
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 SEPIC Mode Application
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
          1. 9.2.3.2.1 Diode
          2. 9.2.3.2.2 Inductor
        3. 9.2.3.3 Application Curves
      4. 9.2.4 Application with Temperature Based LED Current De-rating
        1. 9.2.4.1 Design Requirements
        2. 9.2.4.2 Detailed Design Procedure
        3. 9.2.4.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Community Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
      1. 13.1.2 Tape and Reel Information
  13. 13Mechanical, Packaging, and Orderable Information

1 Features

  • Qualified for Automotive Applications
  • AECQ100 Qualified With the Following Results:
    • Device Temperature Grade 1: –40°C to +125°C Ambient Operating Temperature
  • Input Voltage Operating Range 4.5 V to 40 V
  • Four High-Precision Current Sinks
    • Current Matching 1% (Typical)
    • LED String Current up to 100 mA/Channel
    • Dimming Ratio of 10 000:1 at 100 Hz
  • Integrated Boost/SEPIC Converter for LED String Power
    • Output Voltage up to 45 V
    • Switching Frequency 300 kHz to 2.2 MHz
    • Switching Synchronization Input
    • Spread Spectrum for Lower EMI
  • Power-Line FET Control for Inrush Current Protection and Standby Energy Saving
  • Extensive Fault Detection and Tolerance Features
    • Fault Output
    • Input Voltage OVP, UVLO, and OCP
    • Open and Shorted LED Fault Detection
    • Automatic LED Current Reduction With External Temperature Sensor
    • Thermal Shutdown
  • Minimum Number of External Components

2 Applications

  • Backlight for:
    • Automotive Infotainment
    • Automotive Instrument Clusters
    • Smart Mirrors
    • Heads-Up Displays (HUD)
    • Central Information Displays (CID)
    • Audio-Video Navigation (AVN)

    • System Efficiency

    LP8861-Q1 C010_SNVSA50.png

3 Description

The LP8861-Q1 is an automotive high-efficiency, low-EMI, easy-to-use LED driver with integrated boost/SEPIC converter. It has four high-precision current sinks that can provide high dimming ratio brightness control with a PWM input signal.

The boost/SEPIC converter has adaptive output voltage control based on the LED current sink headroom voltages. This feature minimizes the power consumption by adjusting the voltage to lowest sufficient level in all conditions. The boost/SEPIC converter supports spread spectrum for switching frequency and an external synchronization with dedicated pin. A wide-range adjustable frequency allows the LP8861-Q1 to avoid disturbance for AM radio band.

The LP8861-Q1 has an option to drive an external p-FET to disconnect the input supply from the system in the event of a fault and reduce inrush current and standby power consumption. The device can reduce LED current based on temperature measured with external NTC sensor to protect LED from overheating and extend LED lifetime.

The input voltage range for the LP8861-Q1 is from 4.5 V to 40 V to support automotive stop/start and load dump condition. The LP8861-Q1 integrates extensive fault detection and protection features.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LP8861-Q1 TSSOP (20) 6.50 mm × 4.50 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Schematic

LP8861-Q1 simpl_schem_SNVSA50_page1.gif

4 Revision History

Changes from B Revision (April 2017) to C Revision

  • Expanded descriptions for pins 3, 8, 9, 10, and 16 in Pin Functions Go

Changes from A Revision (November 2015) to B Revision

Changes from * Revision (August 2015) to A Revision

  • Changed maximum Tstg from 160°C to 150°C Go
  • Added last 2 sentences to end of Internal LDO.Go
  • Changed Equation 3 Go
  • Changed Figure 29 to update VIN and VSENSE_N pin connections; removed RISENSE row from sub-section 8.2.2.1 Design RequirementsGo