Linear Technology LT8494 Demo Manual

Description
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
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.
90
80
70
60
50
40
0 0.2 0.4
LOAD CURRENT (A)
Figure 1. LT8494 Efficiency
performance summary
SYMBOL PARAMETER
V Input Supply Range
IN
V Output Voltage
OUT
f Switching Frequency
SW
I Max Output Current
OUT
EFE Efficiency at DC
SEPIC/Boost DC/DC Converter with 2A,
70V Switch, and 7µA Quiescent Current
and BIAS) allow the part
IN
V = 12V
IN
V = 5V
OUT
f = 450kHz
SW
0.6 0.8 1
DC2242A F01
Specifications are at T
CONDITIONS
R = 169kΩ
T
V = 12V
IN
V = 12V, I
IN
DEMO MANUAL DC2242A
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
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.
2.5
2.0
1.5
1.0
0.5
0
0 10
Figure 2. LT8494 Maximum Load Current
(Typical) vs Input Voltage
= 25°C
A
= 1A
OUT
LT8494
20 30 40 50 60
INPUT VOLTAGE (V)
DC2242A F01
MIN TYP MAX
3 60
4.86 5.04 5.24
414 450 477
1
80.3
UNITS
V
V
kHz
A
%
dc2242af
1