1
Rev. 0
DESCRIPTION
LTC3311
3.3V to 1.2V at 50A, 37.5A, 25A Multiphase
2MHz Automotive Low EMI Buck Regulator
Demonstration Circuit 3186A features the
12.5A, low voltage synchronous step-down Silent
Switcher
®
operating as a multiphase 2MHz, 3V to 5.5V
input, 1.2V buck regulator. The DC3186A has three build
options to provide a two phase 25A, three phase 37.5A,
or four phase 50A output solution. The LTC3311 supports
adjustable output voltages from 0.5V to V
IN
and operat-
ing frequencies from 500kHz up to 5MHz in multiphase
operation. All phases of DC3186A operate in forced con-
tinuous mode.
The DC3186A also has an EMI filter to reduce conducted
EMI. This EMI filter can be included by applying the input
voltage at the VIN EMI terminal.
All registered trademarks and trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
The Efficiency vs Load graph shows the efficiency of the
circuit with a 3.3V input for all three build options.
An on-board transient circuit is included to measure fast
transient performance.
The LTC3311 data sheet gives a complete description
of the part, its operation, and application information.
The data sheet must be read in conjunction with this
demo manual. The LTC3311 is assembled in a 3mm ×
3mm LQFN package with exposed pads for low thermal
resistance.
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
DC3186A Input Voltage Range
3
5.5
V
V
OUT
DC3186A Output Voltage Range
1.176
1.2
1.224
V
I
OUT
DC3186A Output Current
DC3186A-A, 4-Phase Build Option, V
IN
≥ 3V
DC3186A-B, 3-Phase Build Option, V
IN
≥ 3V
DC3186A-C, 2-Phase Build Option, V
IN
≥ 3V
50
37.5
25
A
A
A
f
SW
Switching Frequency
1.8
2.2
MHz
EFF
Efficiency
V
IN
= 3.3V, I
OUT
= 15A, 4-Phase
92.5
%
