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 VDD 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

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.