LT3474/LT3474-1
APPLICATIONS INFORMATION
LED Voltage Range
as short as possible. To prevent electromagnetic interfer-
ence (EMI) problems, proper layout of the high frequency
switching path is essential. The voltage signal of the SW
and BOOST pins have sharp rise and fall edges. Minimize
the area of all traces connected to the BOOST and SW
pins and always use a ground plane under the switching
regulator to minimize interplane coupling. In addition, the
The LT3474 can drive LED voltages from 2.4V to 12V. The
LT3474-1 can drive LED voltages from 2.4V to 30V. Be
careful not to exceed the ABSMAX rating of the OUT, LED,
or BOOST pins of the LT3474-1 since the internal output
clamp is disabled. See the Typical Application section for
an example of adding an external output clamp. If the
LED voltage can drift below 2.4V due to temperature or
component variation, add extra series resistance to bring
the overall voltage above 2.4V.
ground connection for frequency setting resistor R (refer
T
to Figure 1) should be tied directly to the GND pin and
not shared with any other component, ensuring a clean,
noise-free connection.
Layout Hints
As with all switching regulators, careful attention must
be paid to the PCB layout and component placement. To
maximize efficiency, switch rise and fall times are made
PWM
SHDN
V
IN
GND
VIA TO LOCAL GND PLANE
VIA TO OUT
Figure 8. Recommended Component Placement
3474fd
17
Linear [ Linear ]
