• Menu
  • Product
  • Email
  • PDF
  • Order now

  • LP8551 High-Efficiency LED Backlight Driver for Notebooks

    • SNVS673E April   2010  – September 2014 LP8551

      PRODUCTION DATA.  

  • CONTENTS
  • SEARCH
  • LP8551 High-Efficiency LED Backlight Driver for Notebooks
  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
  14. IMPORTANT NOTICE

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
  • YZR|25
    • MXBG279
サーマルパッド・メカニカル・データ
発注情報
  • snvs673e_oa
  • snvs673e_pm
search No matches found.
  • Full reading width
    • Full reading width
    • Comfortable reading width
    • Expanded reading width
  • Card for each section
  • Card with all content

 

DATA SHEET

LP8551 High-Efficiency LED Backlight Driver for Notebooks

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

30121270.gif

LED Drive Efficiency

30121292.png

4 Revision History

Changes from D Revision (January 2014) to E Revision

  • Changed formatting to match new TI datasheet guidelines; added Device Information and Handling Ratings tables, Layout, and Device and Documentation Support sections; reformatted Functional Description to Detailed Description and Applications to Applications and Implementation sections, added note to beginning of Apps & Implementations section; moved some waveforms to new Applications Plots subsection. Go

Changes from C Revision (April 2013) to D Revision

  • Added EEPROM noteGo
  • Added EEPROM noteGo

5 Device Default Values

Table 1. Default EEPROM Memory Values

ADDRESS DEFAULT VALUES LP8551
A0H 0111 1111
A1H 1011 0101
A2H 1010 1110
A3H 0111 1011
A4H 0010 0000
A5H 0000 1001
A6H 0000 0000
A7H 0000 0101

6 Pin Configuration and Functions

DSBGA
25
Top View
30121275.gif
DSBGA
25
Bottom View
30121272.gif

Pin Functions

PIN TYPE(1) DESCRIPTION
NUMBER NAME
A1 GND_SW G Boost switch ground
A2 GND_SW G Boost switch ground
A3 EN I Enable input pin
A4 PWM A PWM dimming input. This pin must be connected to GND if not used.
A5 FB A Boost feedback input
B1 SW A Boost switch
B2 SW A Boost switch
B3 ISET A Set resistor for LED current. This pin can be left floating if not used.
B4 FSET A PWM frequency set resistor. This pin can be left floating if not used.
B5 GND_S G Signal ground
C1 VIN P Input power supply up to 22 V. If 2.7 V ≤ VBATT < 5.5 V (Figure 25) then an external 5-V rail must be used for VLDO and VIN.
C2 NC - Not connected
C3 FAULT OD Fault indication output. If not used, can be left floating.
C4 VDDIO P Digital IO reference voltage (1.65 V to 5 V) for I2C interface. If brightness is controlled with PWM input pin then this pin can be connected to GND.
C5 OUT3 A Current sink output
D1 VLDO P LDO output voltage. External 5-V rail can be connected to this pin in low voltage application.
D2 GND G Ground
D3 SCLK I Serial clock. This pin must be connected to GND if not used.
D4 SDA I/O Serial data. This pin must be connected to GND if not used.
D5 OUT2 A Current sink output
E1 NC - Not connected
E2 NC - Not connected
E3 OUT4 A Current sink output
E4 GND_L G LED ground
E5 OUT1 A Current sink output
(1) A: Analog Pin, G: Ground Pin, P: Power Pin, I: Input Pin, I/O: Input/Output Pin, O: Output Pin, OD: Open Drain Pin

 
Texas Instruments

© Copyright 1995-2025 Texas Instruments Incorporated. All rights reserved.
Submit documentation feedback | IMPORTANT NOTICE | Trademarks | Privacy policy | Cookie policy | Terms of use | Terms of sale