lt3695 Linear Technology Corporation, lt3695 Datasheet - Page 25

• Manufacturer Part Number: lt3695
• Description: 1a Fault Tolerant Micropower Step-down Regulator
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
network consisting of R
in Figure 10. C
The SYNC pin must not be directly connected to either
ground or V
is connected to V
ratings of the RT pin. A short between the SYNC pin and
the V
may be connected to SYNC or would short V
if SYNC is grounded.
The recommended connection for SYNC is shown in Fig-
ure 11. If SYNC is to be driven by an external circuitry, R
may be used to isolate this circuitry from V
used in this case to provide a low impedance path for the
synchronization signal. If SYNC is pulled low, R
V
short between SYNC and V
then R
between SYNC and RT.
IN
from being shorted to ground in case of an inadvertent
IN
S
pin could damage an external driver circuit which
protects the RT pin during an inadvertent short
IN
. A short between RT and a SYNC pin that
SS
should not be smaller than 0.22μF .
IN
could violate the absolute maximum
SS
IN
and C
. If SYNC is pulled high to V
Figure 11. The Dashed Lines Show Where a Connection Would Occur
if There Were an Inadvertent Short from SYNC to an Adjacent Pin. In
This Case, R
SS
to RUN/SS as shown
S
Protects Circuitry Connecting to SYNC
IN
SYNC
V
. C
IN
IN
S
to ground
S
prevents
must be
100pF
100k
R
C
S
S
IN
S
,
R
T
If the DA pin or the PGND pin are inadvertently left fl oat-
ing, the current path of the catch diode is interrupted
unless a bypass resistor is connected from DA to ground.
Use a 360mΩ (5% tolerance) resistor rated for a power
dissipation of
where I
is the minimum duty cycle. For example, this would require
a power rating of at least 219mW for an output current of
800mA and a minimum duty cycle of 5%. Make sure not
to exceed V
details) during start-up or overload conditions.
Other Linear Technology Publications
Application Notes 19, 35 and 44 contain more detailed
descriptions and design information for buck regulators
and other switching regulators. The LT1376 data sheet
has a more extensive discussion of output ripple, loop
compensation and stability testing. Design Note 318
shows how to generate a bipolar output supply using a
buck regulator.
SYNC
RT
P = I
LT3695
V
IN
LOAD(MAX)
2
LOAD(MAX)
3695 F11
IN(MAX)
is the maximum load current and DC
• 0.36 • (1 – DC
(see Input Voltage Range section for
MIN
)
LT3695
25
MIN
3695f