1
dc1749bfa
DEMO MANUAL DC1749B
Description
LT8610
42V, 2.5A Micropower Synchronous
Step-Down Regulator
Demonstration circuit 1749B is a 42V, 2.5A micropower
synchronous step-down regulator featuring the
LT
®
8610
.
The LT8610 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 LT8610 to minimize external components
and simplify design.
The SYNC pin on the demo board is grounded by default
for low ripple Burst Mode
®
operation. To synchronous to
an external clock, move JP1 to SYNC and apply the external
clock to the SYNC turret. Once JP1 is on SYNC position,
a DC voltage of higher than 2V or INTV
CC
can be applied
L
, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
to the SYNC turret for pulse-skipping operation. Figure 1
shows the efficiency of the circuit at 12V input.
The demo board has an EMI filter installed. The EMI per-
formance of the board is shown on Figure 2. The limit in
Figure 2 is EN55022 class B, average. It shows the circuit
passes the test with a wide margin.
The LT8610 data sheet gives a complete description of
the part, operation and application information. The data
sheet must be read in conjunction with this quick start
guide for demo circuit 1749B.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1749B
Figure 1. LT8610 12V
IN
to 5V
OUT
Efficiency at 2MHz
Switching Frequency
Figure 2. LT8610 Demo Circuit EMI Performance,
Switching Frequency = 2MHz
LOAD CURRENT (A)
0
60
EFFICIENCY (%)
70
80
90
65
75
85
95
100
0.5
1
dc1749b F01
2
1.5
2.5
START 150kHz
RES BW (CISPR) 9kHz
20
40
60
10
0
–10
30
50
70
80
MKR1 2.003MHz
21.69 dBµV
10 dB/DIV
dc1749b F02
VBW 62kHz
STOP 30MHz
SWEEP 717ms (6637 PTS)
Downloaded from
