1
dc2242af
DEMO MANUAL DC2242A
Description
LT8494
SEPIC/Boost DC/DC Converter with 2A,
70V Switch, and 7µA Quiescent Current
Demonstration circuit 2242A is a monolithic SEPIC con-
verter featuring
LT
®
8494
. The demo board is designed for
5V output from a 3V to 60V input at 450kHz switching
frequency. The max output current is 1A when the input
voltage is above 12V, and is reduced with lower input volt-
age. The quiescent current of LT8494 is less than 7μA when
operating. Dual supply pins (V
IN
and BIAS) allow the part
to automatically operate from the most efficient supply.
Low ripple Burst Mode
®
operation increases the efficiency
at the light load while keeping the output ripple below
10mV. Figure 1 shows the demo board efficiency at 12V
input voltage. Figure 2 shows the maximum load current
with different input voltages of the demo board.
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.
performance summary
The LT8494 data sheet gives a complete description of the
part, operation and application information. The data sheet
must be read in conjunction with this demo manual for
DC2242A. The LT8494 is assembled in 20-lead QFN and
20-lead plastic TSSOP packages. Proper board layout is
essential for maximum thermal and electrical performance.
See the data sheet sections for details.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2242A
Specifications are at T
A
= 25°C
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN
Input Supply Range
3
60
V
V
OUT
Output Voltage
4.86
5.04
5.24
V
f
SW
Switching Frequency
R
T
= 169kΩ
414
450
477
kHz
I
OUT
Max Output Current
V
IN
= 12V
1
A
EFE
Efficiency at DC
V
IN
= 12V, I
OUT
= 1A
80.3
%
LOAD CURRENT (A)
40
EFFICIENCY (%)
60
90
50
70
80
0.4
DC2242A F01
1
0.2
0
0.6
0.8
V
IN
= 12V
V
OUT
= 5V
f
SW
= 450kHz
INPUT VOLTAGE (V)
0
MAXIMUM LOAD CURRENT (A)
1.0
2.5
0.5
1.5
2.0
20
DC2242A F01
60
10
0
30
50
40
Figure 1. LT8494 Efficiency
Figure 2. LT8494 Maximum Load Current
(Typical) vs Input Voltage
