1
dc1787af
DEMO MANUAL DC1787A
DESCRIPTION
LT3759
Wide Input Voltage Range
Boost/SEPIC/Inverting Controller
Demonstration circuit 1787A is a wide input voltage
range SEPIC converter featuring the LT3759 controller. It
converts a 2.8V~36V input to a 12V output, with 1A load
current capability for V
IN
≥ 4V. The converter operates at
a 300 kHz nominal switching frequency, with 91% peak
efficiency. The DC1787A can be easily modified to gener-
ate other output voltages, and can also be optimized for
efficiency and size with narrower input voltage ranges.
The LT3759 is a boost/SEPIC/Inverting controller with a
wide input voltage range, suitable for applications from
single-cell lithium-ion battery portable electronics to high
voltage automotive and industrial power supplies. It also
exhibits low shutdown quiescent current of 1μA, making it
an ideal fit for battery-operated systems. Thanks to a novel
L
, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
FBX pin architecture, the LT3759 can be connected directly
to a divider from either positive output or negative output
voltage to ground. It also packs many popular features
such as soft-start, input undervoltage lockout, adjustable
frequency and synchronization in a small 12-lead exposed
pad MSOP package.
The LT3759 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 1787A.
Design files for this circuit board are available at
http://www.linear.com/demo
(T
A
= 25°C)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Voltage Range, V
IN
2.8
12
36
V
Minimum Startup Voltage
3.0
V
Switching Frequency
I
OUT
= 0.5A
300
kHz
Output Voltage, V
OUT
V
IN
= 2.8V~36V
I
OUT
= 0mA~0.5A
11.64
12.0
12.36
V
Maximum Continuous Output Current, I
OUT
V
IN
≥ 2.8V
0.5
A
V
IN
≥ 4.0V
1
A
Output Voltage Ripple (Peak-to-Peak)
V
IN
= 12V, I
OUT
= 1A
90
mV
Typical Efficiency
V
IN
= 12V, I
OUT
= 1A
91
%
