Linear Technology DC2522A Manual

Description
Demonstration circuit 2522A is a 42V, 2A/3A peak micro-
power synchronous step-down regulator featuring the
LT 8609S. 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 batter-
ies and industrial supplies. The LT8609S is a compact,
high efficiency, high speed synchronous monolithic step-
down switching regulator that consumes only 2.5μA of
quiescent current when output is regulated at 5V. Top
and bottom power switches, compensation components
and other necessary circuits are inside of the LT8609S to
minimize external components and simplify design.
The SYNC pin on the demo board is grounded by default
for low ripple Burst Mode
SKIPPING position can change the operation mode to
pulse-skipping operation. Once JP1 is on SPREAD SPEC-
TRUM position, V
EMI spread spectrum operation. To synchronous to an
performance summary
SYMBOL PARAMETER
V Input Voltage Range
IN
V Output Voltage
OUT
I Maximum Output Current
OUT
f Switching Frequency
SW
EFE Efficiency at DC
Arrow.com.
Downloaded from
Synchronous Step-Down Regulator
operation. Move JP1 to PULSE
®
is applied to the SYNC pin for low
CC
DEMO MANUAL DC2522A
42V, 2A/3A Peak Micropower
external clock, move JP1 to SYNC and apply the external
clock to the SYNC turret. Figure 1 shows the efficiency
of the circuit.
The demo board has an EMI filter installed. The radiated
EMI performances of the board (with EMI filter) are shown
in Figures 2 and 3. The red lines in Figures 2 and 3 are
CISPR25 class 5 peak limit. To use the EMI filter, the input
should be tied to VEMI, not V
a 0Ω jumper on the board by default now, can be added
in the EMI filter to further reduce the conducted emission.
The LT8609S 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 DC2522A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2522A
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Analog Devices, Inc. All other trademarks are the property of their respective owners.
Specifications are at T = 25°C
A
CONDITIONS
V = 12V, I = 1A
IN OUT
LT8609S
. An inductor L2, which is
IN
MIN TYP MAX UNITS
5.5 42
4.8 5 5.2
2
1.85 2 2.15
93.1
dc2522af
1
V
V
A
MHz
%