Linear Technology DC1992A Demo Manual

Description
Demonstration circuit 1992A is a 65V, 2A micropower
synchronous monolithic step-down regulator featuring
the LT 8620. The LT8620 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 LT8620 to minimize external
components and simplify design.
The SYNC pin on the demo board is grounded by default
for low ripple Burst Mode
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
be applied to the SYNC turret pulse skipping operation.
Figure 1 shows the efficiency of the circuit at 12V input.
performance summary
SYMBOL PARAMETER
V Input Supply Range
IN
V Output Voltage
OUT
I Maximum Output Current
OUT
f Switching Frequency
SW
EFE Efficiency at DC
65V, 2A Micropower Synchronous
Monolithic Step-Down Regulator
operation. To synchronous
®
CC
Specifications are at T
100
95
90
85
80
75
70
65
60
0 0.5
Figure 1. LT8620 12V to 5V
IN
DEMO MANUAL DC1992A
The demo board has an EMI filter installed. The board and
the IC are designed to minimize conducted and radiated
EMI. The radiated EMI performances of the board are shown
on Figure 2 to Figure 4. The limits on those figures are
CISPR25, Class 5 peak limits. It shows the circuit passes
the test with a wide margin.
The LT8620 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 1992A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1992A
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
can
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
= 25°C
A
CONDITIONS
I = 1A
OUT
1.0 1.5 2.0
LOAD CURRENT (A)
dc1992a F01
Efficiency at 2MHz Switching Frequency
OUT
LT8620
MIN TYP MAX
5.5 65
4.8 5 5.2
2
1.85 2 2.15
92
UNITS
V
V
A
MHz
%
dc1992af
1