LP8556_16 Datasheet, PDF (1/63 Pages) Texas Instruments – High-Efficiency LED Backlight Driver for Tablets

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LP8556
SNVS871I – JULY 2012 – REVISED MARCH 2016
LP8556 High-Efficiency LED Backlight Driver for Tablets
1 Features
•1 High-Efficiency DC–DC Boost Converter With
Integrated 0.19-Ω Power MOSFET and Three
Switching Frequency Options: 312 kHz, 625 kHz,
and 1250 kHz
• 2.7-V to 36-V Boost Switch Input Voltage Range
Supports Multi-Cell Li-Ion Batteries
(2.7-V to 20-V V_DD Input Range)
• 7-V to 43-V 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 and Open) Detection, UVLO,
TSD, OCP, and OVP (Up to 6 Threshold Options)
• Available in Tiny 20-Pin, 0.4-mm Pitch DSBGA
Package and 24-Pin, 0.5-mm Pitch WQFN
Package
2 Applications
LED Backlights for Tablet LCDs
Simplified Schematic
2.7V - 20V
VIN
CIN
7V ± 43V
L1
D1
1.1 ” 9OUT / VIN ” 15
VOUT
COUT
VDD
SW
EN / VDDIO
1.62V ± 3.6V
CVLDO
RFSET
RISET
Optional
EN / VDDIO
VBOOST
VLDO
FSET
ISET
LP8556
LED1
LED2
LED3
LED4
LED5
MCU
PWM
SDA
SCL
LED6
GNDs
3 Description
The LP8556 device 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 7 V and as high as 43 V. 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 kHz, 625 kHz, and 1250
kHz, which can be set 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 device has a full set of fault-protection
features that ensure robust operation of the device
and external components. The set consists of input
undervoltage lockout (UVLO), thermal shutdown
(TSD), overcurrent protection (OCP), up to 6 levels of
overvoltage protection (OVP), LED open and short
detection.
The LP8556 device operates over the ambient
temperature range of –30°C to +85°C. It is available
in space-saving 20-pin DSBGA and 24-pad WQFN
packages.
PART NUMBER
LP8556
Device Information⁽¹⁾
PACKAGE
BODY SIZE
DSBGA (20) 2.401 mm × 1.74 mm (MAX)
WQFN (24) 4.00 mm × 4.00 mm (NOM)
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.