1
dc1185b-a/-bf
DEMO MANUAL
DC1185B-A/-B
DESCRIPTION
LTC3850EUF
Dual Phase/Dual Output
Synchronous Buck Converter
Demonstration circuit 1185 is a dual phase/dual output
synchronous buck converter featuring the
LTC3850EUF
.
The demo board comes in two versions. The output volt-
ages for version DC1185B-A are 2.0V/10A and 1.8V/10A.
The output voltages for version DC1185B-B are 1.5V/15A
and 1.2V/15A. The input voltage range is 6.5V to 14V for
both versions. For applications that have a 5V ±0.5V input,
the board has an optional resistor to tie the INTVCC pin
to the VIN pin.
The demo board uses a high density, 2-sided drop-in layout.
The power components excluding the bulk output and input
capacitors, fit within a 1.35"
×
0.75" area on the top layer.
The control circuit resides in a 0.60"
×
0.75" area on the
bottom layer. The package style for the LTC3850EUF is a
4mm
×
4mm 28-lead QFN with an exposed ground pad.
L
, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
Note: Q1-Q4 MOSFETs changed on September 10, 2013.
See Schematic Diagram.
PERFORMANCE SUMMARY
The main features of the board include an internal 5V linear
regulator for bias, RUN pins for each output, an EXTVCC
pin and a PGOOD signal. The board can be configured
for either CCM (original setting), Burst Mode
®
, or pulse-
skipping operation with the MODE jumper. The board
also has optional resistors for single output/dual phase
operation, rail tracking, DCR sensing and synchronization
to an external clock.
Design files for this circuit board are available at
http://www.linear.com/demo
Specifications are at T
A
= 25°C
PARAMETER
CONDITION
VALUE
Minimum Input Voltage
6.5V
Maximum Input Voltage
14V
Version DC1185B-A
Output Voltage V
OUT1
I
OUT1
= 0A to 10A
2.0V ±2%
Output Voltage V
OUT2
I
OUT2
= 0A to 10A
1.8V ±2%
Nominal Switching Frequency
500kHz
Full-Load Efficiency
(See Figure 3 for Efficiency Curves)
V
OUT1
= 2.0V, I
OUT1
= 10A, V
IN
= 12V
V
OUT2
= 1.8V, I
OUT2
= 10A, V
IN
= 12V
90.2%
89.5%
Version DC1185B-B
Output Voltage V
OUT1
I
OUT1
= 0A to 15A
1.5V ±2%
Output Voltage V
OUT2
I
OUT2
= 0A to 15A
1.2V ±2%
Nominal Switching Frequency
400kHz
Full-Load Efficiency
(See Figure 4 for Efficiency Curves)
V
OUT1
= 1.5V, I
OUT1
= 15A, V
IN
= 12V
V
OUT2
= 1.2V, I
OUT2
= 15A, V
IN
= 12V
88.1%
86.5%
