LM3466_12 Datasheet, PDF (1/13 Pages) Texas Instruments – Smart Linear LED Driver for Multi-Channel LED Systems

LM3466
February 2, 2012
Smart Linear LED Driver for Multi-Channel LED Systems
General Description
The LM3466 integrates a linear LED driver for lighting sys-
tems which consist of multiple LED strings powered by a
constant current power supply. It equalizes the current pro-
vided by the supply in a pre-set ratio for each active LED
string, where an active string is a fully turned on LED string,
regardless of the number of strings connected to the supply
or the forward voltage of each LED string. If any LED string
opens during operation, the LM3466 automatically equalizes
the supply current through all of the remaining active LED
strings. As a result, the overall brightness of the lighting sys-
tem is maintained even if some LED strings open during
operation.
The LM3466 lighting system is simple to design owing to a
proprietary control scheme. To minimize the component
count, the LM3466 integrates a 70V, 1.5A N-channel power
MOSFET with a current limit of 2.06A. To add one more LED
string to the system, only a single resistor, a capacitor, and a
LM3466 are required. Other supervisory features of the
LM3466 include under-voltage lock-out, fault reporting, ther-
mal latch off, and thermal shutdown protection.
The LM3466 consists of only linear circuitry so that the EMI
of the application circuit is not deteriorated. The LM3466 light-
ing system is EMI friendly if the constant current power supply
used is complied to EMI standards. The LM3466 is available
in the PSOP-8 exposed DAP package.
Features
■ ^{Easy to design and use for lighting systems consisting of}
multiple LED strings (support modular design)
■ ^{Automatically equalizes the current of every active LED}
string, even the forward voltage of each string is different
■ ^{Easy to pre-set and fine-tune current ratio among LED}
strings (e.g. color temperature adjustment or CRI
enhancement)
■ ^{±1% current accuracy at room temperature and ±1.5%}
over temperature
■ ^{Maintains constant output power if some strings open}
(inactive) by automatically equalizing the current of
remaining active LED strings
■ ^{Works with a constant current power supply (ac/dc or dc/}
dc), and no communication to/from the constant current
power supply is required
■ ^{Operates with minimum voltage overhead to maximize}
power efficiency
■ ^{Wide input voltage range from 6V to 70V}
■ ^{Fault status output}
■ ^{Thermal shutdown}
■ ^{Integrated 70V 1.5A MOSFET with 2.06A current limit}
■ ^{Maximum 70V per LED string, 20 LEDs}
■ ^{Linear circuitry does not deteriorate EMI}
■ ^{PSOP-8 exposed DAP package}
Applications
■ ^{Street lamps}
■ ^{Solid state lighting systems}
Typical Application
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