LTC3490 Datasheet, PDF (9/12 Pages) Linear Technology – Single Cell 350mA LED Driver

LTC3490
APPLICATIO S I FOR ATIO
Red Luxeon LEDs
The red, red-orange and amber Luxeon LEDs have a lower
forward voltage than the white, blue and green LEDs. Since
the LTC3490 internal circuitry is powered from the output,
it requires a minimum LED voltage of 2.5V for reliable
operation. The minimum forward voltage on the red LEDs
is only 2.31V. The LTC3490 requires an additional 190mV
for proper operation. In non-dimming applications, this can
be accomplished with a 0.6Ω resistor in series with the
LED. The resistor voltage drops too low in dimming appli-
cations, so a Schottky diode is recommended to keep
sufficient voltage at the output at lower currents.
TYPICAL APPLICATIO S
2-Cell Adjustable Amplitude LED Driver
3.3µH
ON/OFF
+
2 NiMH OR
ALKALINE
CELLS
+
1M
V_IN
SW
CAP
LTC3490
CTRL/SHDN LED
CELLS LOBAT
GND
4.7µF
LUMILEDS
LUXEON
LXHL-BW02
3490 TA03
Soft Turn-Off LED Driver
1 NiMH OR ₊
ALKALINE
CELL
3.3µH
V_IN
SW
ON/OFF
CAP
LTC3490
CTRL/SHDN LED
350mA
1µF 1M
CELLS LOBAT
GND
4.7µF
LUMILEDS
LUXEON
LXHL-BW02
3490 TA04
3490fa
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