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.