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dc1722afa
DEMO MANUAL DC1722A
DESCRIPTION
LTC3864
55V Low I
Q
Step-Down
DC/DC Converter with
100% Duty Cycle Capability
Demonstration circuit 1722A is a high voltage, current
mode DC/DC step-down converter featuring the
LTC
®
3864
.
The board operates from an input range of 3.5V to 55V,
and provides a 5V, 2A output when the input exceeds 5V.
The PMOSFET architecture allows it to operate seamlessly
up to 100% duty cycle, and function as a saturated switch
below the regulation threshold, down to 3.5V
IN
. It operates
at 350kHz and may be synchronized to an external clock.
A soft-start feature controls output voltage slew rate at
start-up, reducing current surge and voltage overshoot.
Burst Mode
®
operation that improves efficiency at light
loads can be enabled with a jumper. A power good output
signal is provided. The demonstration board has options
L
, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
PERFORMANCE SUMMARY
for larger MOSFET and diode packages on the back of the
board for higher output current requirements.
This board is suitable for a wide range of automotive,
telecom, industrial, and other applications. The LTC3864
is available in small 12-pin thermally enhanced MSOP and
DFN packages. For other output requirements, see the
LTC3864 data sheet or contact the LTC factory.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1722A
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Supply Range
3.5
55
V
V
OUT
Output Voltage
5.0
V
I
OUT
Output Current Range, Continuous
0
2
A
f
SW
Switching (Clock) Frequency
350
kHz
V
OUT(P-P)
Output Ripple
V
IN
= 14V, I
OUT
= 2A (20MHz BW)
15
mV
P–P
V
REG
Output Regulation
Line and Load (5.5V
IN
to 55V
IN
, 0A
OUT
to 2A
OUT
)
0.23
%
P
OUT
/P
IN
Efficiency (See Figure 3)
V
IN
=14V, I
OUT
= 2A
84
%
Approximate Size
Component Area x Top Component Height
0.6 × 0.6 × 0.14
Inches
Specifications are at T
A
= 25°C
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