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dc2504af
DEMO MANUAL DC2504A
DESCRIPTION
LT8630 100V, 0.6A
Synchronous Micropower Step-Down
High Efficiency Switching Regulator
Demonstration circuit 2504A is a step-down converter
featuring LT8630. The LT8630 is a monolithic, variable
frequency, current mode synchronous step-down switch-
ing regulator. The demo board is designed for 12V output
from a 13V to 100V input. The wide input range makes it
suitable for regulating power from a variety of sources,
including automotive, industrial systems and telecom
supplies. The power switch, compensation and other
necessary circuits are inside of the LT8630 to minimize
external components and simplify design.
Variable frequency boundary mode switching maximizes
efficiency across the wide input range. Figure 1 shows
the efficiency of the demo board circuit with a 48V input.
The LT8630 will deliver at least 600mA. The maximum
output current depends on V
IN
, V
OUT
and the inductor
value. Figure2 shows the max load current at different
input voltages of the demo board.
The LT8630 switching frequency during the boundary
mode operation is determined by the inductor value, input
voltage, output voltage and output current. The frequency
versus the load current of the demo board at 48V
IN
is
given on Figure 3.
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
The demo board leaves the footprint of an EMI filter on the
backside. Figure 4 shows the radiated EMI performance
of the board when an EMI filter is installed on the board.
The red line in Figure 4 is CISPR25 Class 5 peak limit. The
figure shows that the circuit passes the test with a wide
margin. The conducted EMI can be passed as well with the
right design of the filter. When input EMI filter is required,
the input voltage should be applied at V
EMI
, not V
IN
.
The LT8630 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 Demo circuit 2504A. The LT8630 is assembled in a
20-lead 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/DC2504A
Specifications are at T
A
= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Input Supply Range 13 100 V
V
OUT
Output Voltage 11.71 12.11 12.52 V
I
OUT
Max Output Current V
IN
= 48V, V
OUT
= 12V, L = 22μH 0.6 A
E
FE
Efficiency at DC V
IN
= 48V, I
OUT
= 0.6A 91 %
