SNVS673E April   2010  – September 2014 LP8551

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Default Values
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  Handling Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics
    6. 7.6  Boost Converter Electrical Characteristics
    7. 7.7  LED Driver Electrical Characteristics
    8. 7.8  PWM Interface Characteristics
    9. 7.9  Undervoltage Protection
    10. 7.10 Logic Interface Characteristics
    11. 7.11 I2C Serial Bus Timing Parameters (SDA, SCLK)
    12. 7.12 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 Clock Generation
      2. 8.3.2 Brightness Control Methods
        1. 8.3.2.1  PWM Input Duty Cycle
        2. 8.3.2.2  Brightness Register Control
        3. 8.3.2.3  PWM Direct Control
        4. 8.3.2.4  PWM Calculation Data Flow
        5. 8.3.2.5  PWM Detector
        6. 8.3.2.6  Brightness Control
        7. 8.3.2.7  Resolution Selector
        8. 8.3.2.8  Sloper
        9. 8.3.2.9  PWM Comparator
        10. 8.3.2.10 Current Setting
        11. 8.3.2.11 PWM Frequency Setting
        12. 8.3.2.12 Phase Shift PWM (PSPWM) Scheme
        13. 8.3.2.13 Slope
        14. 8.3.2.14 Driver Headroom Control
      3. 8.3.3 Boost Converter
        1. 8.3.3.1 Operation
        2. 8.3.3.2 Protection
        3. 8.3.3.3 Manual Output Voltage Control
        4. 8.3.3.4 Adaptive Boost Control
      4. 8.3.4 Fault Detection
        1. 8.3.4.1 LED Fault Detection
        2. 8.3.4.2 Undervoltage Detection
        3. 8.3.4.3 Overcurrent Protection
        4. 8.3.4.4 Device Thermal Regulation
        5. 8.3.4.5 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Modes of Operation
    5. 8.5 Programming
      1. 8.5.1 I2C-Compatible Serial Bus Interface
        1. 8.5.1.1 Interface Bus Overview
        2. 8.5.1.2 Data Transactions
        3. 8.5.1.3 Acknowledge Cycle
        4. 8.5.1.4 “Acknowledge After Every Byte” Rule
        5. 8.5.1.5 Addressing Transfer Formats
        6. 8.5.1.6 Control Register Write Cycle
        7. 8.5.1.7 Control Register Read Cycle
        8. 8.5.1.8 Register Read and Write Detail
      2. 8.5.2 EEPROM
    6. 8.6 Register Map
      1. 8.6.1 Register Bit Explanations
        1. 8.6.1.1 Brightness Control
        2. 8.6.1.2 Device Control
        3. 8.6.1.3 Fault
        4. 8.6.1.4 Identification
        5. 8.6.1.5 Direct Control
        6. 8.6.1.6 Temp MSB
        7. 8.6.1.7 Temp LSB
        8. 8.6.1.8 EEPROM Control
      2. 8.6.2 EEPROM Bit Explanations
        1. 8.6.2.1 EEPROM Register Map
        2. 8.6.2.2 EEPROM Address 0
        3. 8.6.2.3 EEPROM Address 1
        4. 8.6.2.4 EEPROM Address 2
        5. 8.6.2.5 EEPROM Address 3
        6. 8.6.2.6 EEPROM Address 4
        7. 8.6.2.7 EEPROM Address 5
        8. 8.6.2.8 EEPROM Address 7
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Application Using Internal LDO
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Recommended External Components
            1. 9.2.1.2.1.1 Inductor Selection
            2. 9.2.1.2.1.2 Output Capacitor
            3. 9.2.1.2.1.3 LDO Capacitor
            4. 9.2.1.2.1.4 Output Diode
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Application with Low-Input Voltage
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Trademarks
    2. 12.2 Electrostatic Discharge Caution
    3. 12.3 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • High-Voltage DC/DC Boost Converter with Integrated FET; Four Switching Frequency Options: 156/312/625/1250 kHz
  • 2.7-V to 22-V Input Voltage Range to Support 1x to 5x Cell Li-Ion Batteries
  • 50-mA High-Precision LED Current Sinks
  • Adaptive LED Current Sink Headroom Control for Maximum System Efficiency
  • Programmable PWM Resolution 8 to 13 Bits
  • I2C and PWM Input Duty Cycle Brightness Control
  • PWM Output Frequency and LED Current Set Through Resistors
  • 4 LED Outputs with LED Fault (short/open) Detection
  • Low Input Voltage, Overtemperature, Overcurrent Detection, and Shutdown
  • Minimum Number of External Components

2 Applications

  • Notebook and Tablet LCD Display LED Backlight
  • LED Lighting

3 Description

The LP8551 is a white LED driver with integrated boost converter. It has four adjustable current sinks which can be controlled by PWM input or with I2C-compatible serial interface.

The boost converter has adaptive output voltage control based on the LED driver voltages. This feature minimizes the power consumption by adjusting the voltage to lowest sufficient level in all conditions.

LED outputs have 8-bit current resolution and up to 13-bit PWM resolution to achieve smooth and precise brightness control. Proprietary Phase Shift PWM control is used for LED outputs to reduce peak current from the boost converter, thus making the boost capacitors smaller. The Phase Shifting scheme also eliminates audible noise.

Internal EEPROM is used for storing the configuration data. This makes it possible to have minimum external component count and make the solution very small.

The LP8551 has safety features which make it possible to detect LED outputs with open or short fault. As well, low input voltage and boost overcurrent conditions are monitored, and chip is turned off in case of these events. Thermal de-rating function prevents overheating of the device by reducing backlight brightness when set temperature has been reached.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (MAX)
LP8551 DSBGA (25) 2.49 mm x 2.49 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Simplified Schematic

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LED Drive Efficiency

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