1 Features

1• 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.