1
dc1821bf
DEMO MANUAL DC1821B
DESCRIPTION
LTC3114EDHC-1
40V, 1A Synchronous Buck-Boost DC/DC
Converter with Output Current Limit
Demonstration circuit 1821B features the
, a
wide operating range synchronous monolithic buck-boost
converter with programmable average output current.
The DC1821B demo board has two user selectable operat-
ing modes: Burst Mode
®
operation and Fixed Frequency
PWM (JP2). There is also an accurate programmable RUN
pin which is used to ENABLE the converter (JP1).
The LTC3114-1 uses average current mode control to
simplify voltage loop compensation and provide good line
and load transient response.
The DC1821B operates with a 2.7V to 40V input volt-
age range. The demo board has been designed with the
output voltage set to 5V. The LTC3114-1 incorporates a
proprietary low noise switching algorithm which optimizes
efficiency with input voltages above, below or equal to the
output voltage and ensures seamless transitions between
operating modes.
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.
In PWM mode, the LTC3114-1 operates at 1.2MHz to
optimize small size with high efficiency operation.
The demo board also incorporates diode D1 to backfeed
V
CC
to improve efficiency in some applications. If the
demo board output voltage is changed to a higher volt-
age, D1 should be removed. Consult the data sheet for
more information.
Figure 1 shows typical demo board efficiency. Figure 2
shows the response to an input voltage step while Figure 3
shows the load step response.
The LTC3114-1 data sheet has detailed information about
the operation, specifications, and applications of the part.
The data sheet should be read in conjunction with this
Quick Start Guide.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1821B
PARAMETER
TYP
Input Voltage Range
2.7V to 40V
V
OUT
5V
I
OUT
(See Note 1)
1A for V
IN
> 6V
Efficiency
See Figure 1
NOTE 1: The demo board output current is a function of V
IN
. Please refer to the data sheet for more information.
PERFORMANCE SUMMARY
Specifications are at T
A
= 25°C
