AAT2400 Datasheet, PDF (1/32 Pages) Skyworks Solutions Inc. – Sixteen-Channel White LED Driver Solution

DATA SHEET
AAT2400/2401
Sixteen-Channel White LED Driver Solution
with Full LED Current and Timing Control
General Description
The AAT2400/2401 is a highly integrated, high efficiency
white LED backlight solution for large size LCD panels
used in LCD TVs. To accommodate power requirements,
the solution consists of two devices, a master device
(AAT2400) and a slave device (AAT2401). The devices
operate from a regulated 24V DC power supply. The
master device supplies a 40V rail to drive 10 series LEDs
with a typical V_F of 3.6V. 16 precision current sinks split
evenly between the master and slave devices provide
constant current drive for up to 160 white LEDs.
A SPI compatible interface operates up to 30MHz, allow-
ing fast, independent digital control of each current sink.
Full scale LED current is programmed from 30mA to
100mA using an external resistor. LED brightness varia-
tion is compensated by setting relative current sink mag-
nitudes with an 8-Bit Dot Correction register for each
LED current sink.
The AAT2400/2401 provides a 12-bit programmable
phase delay per LED current sink that can be used to
synchronize the LEDs to V_SYNC. Device addressing pro-
vides for up to 256 LED strings. A 12-bit programmable
Gray Scale PWM brightness setting is generated via a
clock from a PLL synchronized to V_SYNC, or from the
external GSCLK pin.
The AAT2400/2401 provides fault handling and fault
reporting through the interface. If LEDs are shorted on
one or more strings, the current sinks will maintain
operation due to the high voltage rating of the outputs.
However, a fault condition will be reported on the open
drain Fault pin. Similarly, if an open circuit is detected or
an over-temperature condition arises, the fault is report-
ed on the Fault pin. When a fault is reported, the nature
of the fault condition can be read through the serial
interface.
The AAT2400 boost converter provides an output voltage
regulated by the string with the highest voltage require-
ment allowing a wide range of LED characteristics, while
maintaining the lowest possible power dissipation. The
boost switching frequency is 600kHz to allow for opti-
mum efficiency with the smallest external filter.
Alternatively, the device may be synchronized to an
external clock. Current mode control provides fast
response to line and load transients. Thermal protection
circuitry shuts down the boost converter and the current
sinks in the event of an over-temperature condition.
The AAT2400 and AAT2401 are available in Pb-free, ther-
mally enhanced 36-pin 5x5mm TQFN packages.
Features
• V_IN Range: 10.8V – 28V
• Integrated Boost Converter
▪ VOUT(MAX): 40V
▪ IOUT(MAX): 1.6A
• Up to 95% Efficiency
• Switching Frequency Options
▪ 600 kHz
▪ Sync to External Clock (optional)
• 16 LED Current Sinks up to 100mA/ch
▪ ±2.5% Accuracy (60mA)
▪ ^{±2.0% Matching (60mA)}
• SPI Interface
▪ ^{Digitally Programmable Individual Channels}
▪ Up to 30MHz Clock Speed
▪ Read/Write Registers
• Precision PWM Digital Brightness Control
▪ 12-bit Individual Gray Scale PWM Brightness
▪ 12-bit Individual Channel Phase Delay
▪ 8-bit Individual Current Setting (Dot Correction)
▪ VSYNC Derived Internal Oscillator
• V_SYNC PWM and Delay Synchronization
• Device Addressing
▪ 16 Possible Address Settings
▪ Up to 256 Current Sinks
• Fault Reporting
• Integrated Fault Protection
▪ Open/Short LED(s)
▪ Current Limit Protection
▪ Over-Voltage Protection
▪ Over-Temperature Protection
• Soft-Start to Minimize Inrush Current
• TQFN55-36 Low Profile Package
• -40°C to +85°C Temperature Range
Applications
• _{Large Size LCD TV, Panels}
• _{White LED Backlight}
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [e-mail] • www.skyworksinc.com
202307A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 24, 2012
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