1
Rev. 0
DESCRIPTION
LTC3310S
5V, 10A Synchronous Step Down
Silent Switcher in 3mm x3mm LQFN
Demonstration Circuit DC2629A features the
10A, Low Voltage, Synchronous Step-Down Silent
Switcher
®
2 operating as a 2MHz 3.3V to 1.2V 10A buck
regulator. The LTC3310S supports output voltages from
0.5V to V
IN
with operating frequencies from 500kHz up
to 5MHz. The LTC3310S is a compact, ultralow emission,
high efficiency, and high speed synchronous monolithic
step-down switching regulator. The integrated bypass
capacitors optimize all the fast current loops and make it
easier to minimize EMI/EMC emissions by reducing layout
sensitivity. Fast minimum on-time of 35ns enables high
V
IN
to low V
OUT
conversion at high frequency.
DC2629A is set up to run in Forced Continuous Mode
with a 2MHz switching frequency but can be configured
to Pulse Skip Mode and different switching frequencies.
RT is connected to V
IN
which sets the MODE/SYNC pin
as an input and allows the LTC3310S to sync from an
external clock. Connecting the MODE/SYNC pin to V
IN
sets the mode to Forced Continuous Mode and connecting
the MODE/SYNC pin to GND sets the mode to Pulse Skip
Mode. The Efficiency vs. Load graph shows the efficiency
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PERFORMANCE SUMMARY
and the power loss of the circuit with a 3.3V input in
forced continuous mode operation.
The DC2629A also has an EMI filter to reduce conducted
EMI. This EMI filter can be included by applying the input
voltage at the V
IN
EMI terminal. The EMI performance of
the board is shown in the EMI TEST RESULTS section.
The red lines in the EMI performance graphs illustrate
the CISPR25 Class 5 peak limits for the conducted and
radiated emission tests.
The LTC3310S data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this demo. The
LTC3310S is assembled in a 3mm x 3mm LQFN package
with exposed pads for low thermal resistance. The layout
recommendations for low EMI operation and maximum
thermal performance are available in the data sheet sec-
tion Low EMI PCB Layout.
Design files for this circuit board are available
Specifications are at T
A
= 25°C
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
/V
IN
EMI
DC2629A Input Voltage Range
2.25
5.5
V
V
OUT
DC2629A V
OUT
Voltage Range
1.183
1.2
1.217
V
I
OUT
DC2629A Output Current
10
A
f
SW
Switching Frequency
1.8
2.2
MHz
EFF
Efficiency
V
IN
= 3.3V, I
OUT
= 5A
91
%
