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dc2565af
DEMO MANUAL DC2565A
Description
LT8607
42V, 0.75A Micropower Synchronous
Step-Down Regulator
Demonstration Circuit 2565A is a 42V, 0.75A micropower
synchronous step-down regulator featuring the LT
®
8607.
The demo board is designed for 5V output from a 5.5V
to 42V input. The wide input range allows a variety of
input sources, such as automotive batteries and indus-
trial supplies. The LT8607
is a compact, high efficiency,
high speed synchronous monolithic step-down switch-
ing regulator that consumes less than 3μA of quiescent
current when output is regulated at 5V. Top and bottom
power switches, compensation components and other
necessary circuits are inside of the LT8607 to minimize
external components and simplify design.
The SYNC pin on the demo board is grounded by default
for low ripple Burst Mode
®
operation. Move JP1 to PULSE
SKIPPING position can change the operation mode to
pulse-skipping operation. Once JP1 is on SPREAD SPEC-
TRUM position, V
CC
is applied to the SYNC pin for low
EMI spread spectrum operation. To synchronous to an
external clock, move JP1 to SYNC and apply the external
clock to the SYNC turret. Figure 1 shows the efficiency
of the circuit.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Analog Devices, Inc. All other trademarks are the property of their respective owners.
performance summary
The demo board has an EMI filter installed. The radiated
EMI performances of the board (with EMI filter) are shown
in Figure 2 and Figure 3. The red lines in Figure 2 and
Figure 3 are CISPR25 Class 5 peak limit. To use the EMI
filter, the input should be tied to V
EMI
, not V
IN
. An induc-
tor L2, which is a 0Ω jumper on the board by default
now, can be added in the EMI filter to further reduce the
conducted emission.
The LT8607 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 DC2565A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2565A
Specifications are at T
A
= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Input Voltage Range 5.5 42 V
V
OUT
Output Voltage 4.8 5 5.2 V
I
OUT
Maximum Output Current 0.75 A
f
SW
Switching Frequency 1.85 2 2.15 MHz
EFE Efficiency at DC V
IN
= 12V, I
OUT
= 0.75A 92.4 %
