LP8555 High-Efficiency LED Backlight Driver for Tablet PCs | TI.com

LP8555 (ACTIVE) High-Efficiency LED Backlight Driver for Tablet PCs

 

Description

The LP8555 is a high efficiency LED driver with integrated dual DC-DC boost converters. It has 12 high-precision current sinks that can be controlled by a PWM input signal, an I2C master, or both.

Dual-boost configuration of LP8555 shares the load to two inductors and allows thinner overall solution size and better efficiency compared to single-boost solutions. 12 LED strings allows driving high number of LEDs with optimal efficiency since boost conversion ratio can be kept low.

The boost 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 LED string auto-detect function enables use of the same device in systems with 2 to 12 LED strings for the maximum design flexibility. Proprietary Hybrid PWM and Current dimming mode enables additional system power savings. Phase-shift PWM allows reduced audible noise and smaller boost output capacitors. Flexible CABC support combines brightness level selections based on the PWM input and I2C commands.

Features

  • Dual High-Efficiency DC/DC Boost Converters
  • 2.7-V to 20-V VDD Range
  • 12 50-mA High-Precision LED Current
    Sinks With 12-Bit Brightness Control
  • Adaptive LED Current Sink Headroom
    Controls for Maximum System Efficiency
  • LED String Count Auto-Detection
  • Phase-Shifted PWM Mode for Reduced Audible
    Noise
  • PWM Input Duty-Cycle and/or I2C-Register
    Brightness Control
  • Hybrid PWM and Current Dimming for Higher LED
    Drive Optical Efficiency
  • Flexible CABC Support
  • EPROM, I2C-Register, or External Resistors
    for Configuration
  • Improved Boost EMI Performance with Slew-Rate Control,
    Spread Spectrum, and Phase-Shifted Switching
  • Extensive Fault Detection Schemes

Parametrics

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Part number Order Channels (#) Vin (Min) (V) Vin (Max) (V) Vout (Min) (V) Vout (Max) (V) Switching frequency (Max) (kHz) Type LED current per channel (mA) LED (#) Topology Shutdown current (Typ) (uA) Peak efficiency (%) LED configuration Function Features Operating temperature range (C) Package Group Package size: mm2:W x L (PKG)
LP8555 Order now 12     2.7     20     7     28     1000     Inductive     50     96     Boost     3     93     6 LED channels
Dual
Parallel    
Backlight     Adjustable Switch Frequency
Analog/PWM Mixed Dimming
CABC
Edge Rate Control
I2C Control
Integrated Switch
OVP
PWM Control
Thermal Shutdown    
-40 to 85     DSBGA | 36     See datasheet (DSBGA)    
LM36274 Order now 4     2.7     5     27     30     1050     Inductive     30     32     Boost
Current Sink    
1.2     92     Parallel
Series    
  Adjustable Switch Frequency
CABC
I2C Control
OVP
Thermal Shutdown    
-40 to 85     DSBGA | 24     See datasheet (DSBGA)    
LM36923H Order now 3     2.5     5.5     0     37     1050     Inductive     30     30     Boost
Current Sink
Multi-Channel    
1.2     92     Parallel
Series    
  Adjustable Switch Frequency
CABC
Direct PWM Dimming
Enable/Shutdown
I2C Control
OVP
Thermal Shutdown    
-40 to 85     DSBGA | 12     12DSBGA: 2 mm2: 1.16 x 2 (DSBGA | 12)    
LP8553 Order now 4     2.7     22     10     40     1250     Inductive     50     40     Boost     1     93         PWM Control     -30 to 85     DSBGA | 25     25DSBGA: 8 mm2: 2.8 x 3 (DSBGA | 25)    
LP8556 Order now 6     2.7     20     7     48     1250     Inductive     50     60     Boost     0.1