HIGH EFFICIENCY, THINSOT™ SYNCHRONOUS BUCK REGULATOR
DEMO BOARD QUICK START GUIDE DC480
LTC3405A
DESCRIPTION
Demonstration circuit DC480 is a constant-frequency
step-down converter that uses the LTC3405A monolithic
synchronous buck regulator. The DC480 has an input
voltage range of 2.5V to 5.5V, and is capable of deliver-
ing up to 300mA of output current at 3.0V minimum in-
put voltage. In Burst Mode™ operation, the DC supply
current is typically only 25µA at no load, and less than
1µA in shutdown. In switching -noise sensitive applica-
tions, grounding the MODE pin enables Burst Mode™
operation. These features, plus the LTC3405A coming in
a tiny 6-Pin SOT-23 package and having an operating
frequency of 1.5 MHz (allowing the exclusive use of low
profile surface mount components), make the DC480
demo board an ideal circuit for use in battery-powered,
hand-held applications.
Gerber files for this circuit are
available. Call the LTC Factory.
QUICK START
The DC480 demonstration board is easy to set up to
evaluate the performance of the LTC3405A. Refer to Fig-
ure 1 for proper measurement equipment setup.
When the board is right-side up (the title is
legible at the top of the board), the output voltage tur-
ret is on the left side of the board, and the input volt-
age turret is on the right side of the board. Set up the
circuit appropriately.
NOTE:
Do not hot-plug V
IN
or increase V
IN
over the
rated maximum supply voltage of 6V, or th e part may
be damaged.
NOTE:
2.
Connect
the load between the V
OUT
and GND termi-
nals on the
left side
of the board. Refer to figure 1 for
the proper measurement equipment setup.
3.
Select
Please follow the procedure outlined below for proper
operation.
1.
Connect
the input power supply to the V
IN
and GND
terminals on the
right-side
of the board.
the desired operating mode using JP1. To se-
lect pulse-skipping mode, tie the MODE pin to V
IN
by
inserting the jumper into the lower position. Inserting
the jumper into the upper position connects the pin to
ground, which causes Burst Mode™ operation. Do
not leave this pin floating.
shut down the circuit, connect the RUN pin to
ground by inserting the JP2 jumper into the upper
position. Do not leave this pin floating.
4.
To
Figure 1. Proper Measurement Equipment Setup
1
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