Drive up to Four Strings of Ten 120mA LEDs with 3000:1 True Color PWM Dimming

News Release ⎜
Drive up to Four Strings of Ten 120mA LEDs with
3000:1 True Color PWM Dimming
MILPITAS, CA – January 22, 2009 – Linear Technology announces the LT3599, a 45V,
2.1MHz DC/DC boost mode converter designed to operate as a constant current LED driver for
up to 40 white LEDs. From a 12V input, the LT3599 can drive up to four strings of LEDs, each
with up to ten 120mA white LEDs in series while delivering efficiencies up to 90%. Its
multichannel capability makes it ideal for medium-sized TFT-LCD backlighting applications.
The LT3599’s input voltage range of 3.1V to 30V is well-suited for automotive, medical and
industrial applications. The device offers 1.5% LED current matching to ensure uniform
brightness of the display. Dimming ratios as high as 3,000:1 can be attained by using True Color
PWM™ dimming. A programmable 200kHz to 2.1MHz fixed frequency operation and current
mode architecture offers stable operation over a wide range of supply and output voltages while
minimizing the size of the external components. Additionally, the switching frequency is
synchronizable to an external clock for improved noise immunity. The LT3599’s thermally
enhanced 5mm x 5mm QFN or TSSOP-28E package provides a highly compact solution
footprint for LED backlighting applications.
The LT3599 uses a single 2A, 45V internal switch to provide a boost mode constant
current source. However, even when VIN exceeds VOUT, the LT3599 will continue to regulate the
LED current. The internal boost converter uses an adaptive feedback loop to regulate the output
voltage slightly higher than the required LED voltage to ensure maximum efficiency. If any of
the LED strings experiences an open circuit, it will continue to regulate the existing strings and
signals the OPENLED alert pin. If higher current LEDs are required, multiple strings can be
combined, enabling it to drive up to two strings of ten 240mA LEDs. Additional features include
LED current derating based on junction temperature and/or LED temperature and programmable
overvoltage protection when all LED strings are disconnected.
Drive up to Four Strings of Ten 120mA LEDs with
3000:1 True Color PWM Dimming
page 2
The LT3599EUH is available in a 32-lead 5mm x 5mm QFN package and the
LT3599EFE is offered in a TSSOP-28E. 1,000-piece pricing starts at $3.25 each and $3.35 each,
respectively. Industrial grade versions, the LT3599IUF and LT3599IFE, are tested and
guaranteed to operate to the -40°C to 125°C operating junction temperature and are priced at
$3.82 each and $3.94 each, respectively, in 1,000-piece quantities. All versions are available
from stock. For more information, visit
Photo Caption: 45V, 4-Channel Boost Mode LED Driver
Summary of Features: LT3599
True Color PWM Dimming Ratio up to 3000:1
Drives Four Strings of LEDs up to 120mA
±1.5% Accurate LED Current Matching
Wide Input Voltage Range: 3.1V to 30V
Output Voltage Up to 44V
Regulates LED Current Even When VIN > VOUT
Disconnects LEDs in Shutdown
Programmable Maximum VOUT (Regulated)
Open/Short LED Protection & Fault Flags
Programmable LED Current Derating
Adjustable Frequency: 200kHz to 2.1MHz
Synchronizable to an External Clock
Analog Dimming up to 20:1
Programmable Input UVLO with Hysteresis
Thermally Enhanced 32-Pin (5mm × 5mm) QFN & 28-Pin TSSOP Packages
About Linear Technology
Linear Technology Corporation, a manufacturer of high performance linear integrated circuits,
was founded in 1981, became a public company in 1986 and joined the S&P 500 index of major
public companies in 2000. Linear Technology products include high performance amplifiers,
comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery
chargers, data converters, communications interface circuits, RF signal conditioning circuits,
uModule™ products, and many other analog functions. Applications for Linear Technology’s
high performance circuits include telecommunications, cellular telephones, networking products
such as optical switches, notebook and desktop computers, computer peripherals,
video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer
products such as digital cameras and MP3 players, complex medical devices, automotive
electronics, factory automation, process control, and military and space systems.
LT, LTC, LTM and
are registered trademarks and uModule is a trademark of Linear Technology Corp. All other
trademarks are the property of their respective owners.
Press Contacts:
John Hamburger, Director Marketing Communications
[email protected]
Tel: 408-432-1900 ext 2419
Doug Dickinson, Media Relations Manager
[email protected]
Tel: 408-432-1900 ext 2233