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.