LP8552 Datasheet, PDF (1/39 Pages) Texas Instruments – High-Efficiency LED Backlight Driver for Notebooks

LP8552
June 6, 2012
High-Efficiency LED Backlight Driver for Notebooks
General Description
The LP8552 is a white LED driver with integrated boost con-
verter. It has six adjustable current sinks which can be con-
trolled 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 suffi-
cient level in all conditions.
LED outputs have 8-bit current resolution and up to 13-bit
PWM resolution with additional 1-3 bit dithering 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 ca-
pacitors smaller. The Phase Shifting scheme also eliminates
audible noise.
Automatic PWM dimming at lower brightness values and cur-
rent dimming at higher brightness values can be used to
improve the optical efficiency.
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.
LP8552 has safety features which make it possible to detect
LED outputs with open or short fault. As well low input voltage
and boost over-current 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.
LP8552 is available in a micro SMD 25-bump package.
Features
■ ^{High-voltage DC/DC boost converter with integrated FET}
with four switching frequency options: 156/312/625/1250
kHz
■ ^{2.7V to 22V input voltage range to support 1x…5x cell Li-}
Ion batteries
■ ^{Programmable PWM resolution}
— 8 to 13 true bit (steady state)
— Additional 1 to 3 bits using dithering during brightness
changes
■ ^{I2C and PWM brightness control}
■ ^{Automatic PWM & current dimming for improved efficiency}
■ ^{PWM output frequency and LED current set through}
resistors
■ ^{Optional synchronization to display V}_SYNC ^signal
■ ^{6 LED outputs with LED fault (short/open) detection}
■ ^{Low input voltage, over-temperature, over-current}
detection and shutdown
■ ^{Minimum number of external components}
■ ^{Micro SMD 25-bump package, 2.466 x 2.466 x 0.6 mm}
Applications
■ ^{Notebook and Netbook LCD Display LED Backlight}
■ ^{LED Lighting}
Typical Application (1)
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