LP8556 Datasheet, PDF (1/52 Pages) Texas Instruments – High-Efficiency LED Backlight Driver for Tablets

LP8556
www.ti.com
SNVS871B – JULY 2012 – REVISED SEPTEMBER 2012
LP8556 High-Efficiency LED Backlight Driver for Tablets
Check for Samples: LP8556
FEATURES
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•2 High Efficiency DC/DC Boost Converter with
Integrated 0.19Ω Power MOSFET and Three
Switching Frequency Options: 312 / 625 / 1250
kHz
• 2.7V to 36V Boost Switch Input Voltage Range
Supports Multi-cell Li-Ion Batteries (2.7V - 20V
VDD Input Range)
• 7V to 43V Boost Switch Output Voltage Range
Supports as few as 3 WLEDs in Series per
Channel and as Many as 12
• Configurable Channel Count (1 to 6)
• Up to 50 mA per Channel
• PWM and / or I²C Brightness Control
• Phase-Shift PWM Mode Reduces Audible
Noise
• Adaptive Dimming for Higher LED Drive
Optical Efficiency
• Programmable Edge-rate Control and Spread
Spectrum Scheme Minimize Switching Noise
and Improve EMI Performance
• LED Fault (short/open) Detection, UVLO, TSD,
OCP and OVP (up to 6 Threshold Options)
• Available in Tiny 20-bump, 1.715 mm x 2.376
mm x 0.6 mm, 0.4 mm pitch, DSBGA Package,
and 24-pad, 4 mm x 4 mm x 0.8 mm, 0.5 mm
Pitch, WQFN Package.
APPLICATIONS
• Tablet LCD Display LED Backlight
DESCRIPTION
LP8556 is a white LED driver featuring an asynchronous boost converter and six high precision current sinks that
can be controlled by a PWM signal or an I²C master.
The boost converter uses adaptive output voltage control for setting the optimal LED driver voltages as low as 7V
and as high as 43V. This feature minimizes the power consumption by adjusting the output voltage to the lowest
sufficient level under all conditions. The converter can operate at three switching frequencies: 312, 625 and 1250
kHz settable with an external resistor or pre-configured via EPROM. Programmable slew rate control and spread
spectrum scheme minimize switching noise and improve EMI performance.
LED current sinks can be set with the PWM dimming resolution of up to 15 bits. Proprietary adaptive dimming
mode allows higher system power saving. In addition, phase shifted LED PWM dimming allows reduced audible
noise and smaller boost output capacitors.
The LP8556 has a full set of safety features that ensure robust operation of the device and external components.
The set consists of input under-voltage lockout, thermal shutdown, over-current protection, up to 6 levels of over-
voltage protection, LED open and short detection.
The LP8556 operates over the ambient temperature range of -30°C to +85°C. It is available in space saving 20-
bump DSBGA and 24-pad WQFN packages.
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Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
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PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2012, Texas Instruments Incorporated