Product category:
Power Supply ICs and Controllers
News Release from: Linear Technology Corp | Subject: LT3478/-1
Edited by the Electronicstalk Editorial
Team on 10 August 2007
Convertors keep backlights constant
DC/DC convertors drive high current LEDs at constant current for applications such as automotive display backlighting.
Linear Technology has launched a pair of 40V/4.5A DC/DC convertors designed to drive high current LEDs at constant current Their 2.8 to 36V input range is ideal for a wide variety of applications, including automotive, industrial and architectural lighting
This article was originally published on Electronicstalk on 28 Jul 2004 at 8.00am (UK)
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In boost mode, the LT3478/-1 can drive up to six 700mA LEDs in series from a 12V input, making the device ideal for applications such as automotive display backlighting.
The LT3478-1 uses an internal current sense resistor, limiting output current to 1A, whereas the LT3478 uses an external sense resistor to extend the maximum LED current up to 4.5A.
Both parts deliver efficiencies up to 90% in boost mode from a thermally enhanced TSSOP-16E package.
The devices use True Color PWM dimming, which delivers constant LED colour with dimming ranges up to 3000:1, and a fixed frequency, current mode architecture offers stable operation over a wide range of supply and output voltages.
A frequency adjust pin enables the user to program the frequency between 200kHz and 2.25MHz, optimising efficiency while minimising external component size.
The LT3478/-1 senses output current at the high side of the LED, enabling buck, buck-boost or boost configurations.
One of the two control pins can be used to program maximum LED current and the other can be used to program a reduction in maximum LED current with increases in temperature, thereby maximising LED usage and improving overall reliability.
Other features include inrush current protection, open LED protection and programmable soft-start.
The LT3478EFE and LT3478EFE-1 are available from stock in thermally enhanced 16-lead TSSOP-16E packages.
Pricing starts at US $3.60 each for both versions.
Extended-temperature industrial-grade versions, the LT3478IFE and LT3478IFE-1, are also available from stock.
Pricing starts at US $4.32 each for both versions in 1000-piece quantities. Request a free brochure from Linear Technology Corp ...
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