LTC3611EWP LINER [Linear Technology], LTC3611EWP Datasheet - Page 15

• Manufacturer Part Number: LTC3611EWP
• Description: 10A, 32V Monolithic Synchronous Step-Down DC/DC Converter
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
RMS and must be bypassed to ground with a minimum of
4.7μF tantalum or ceramic capacitor. Good bypassing is
necessary to supply the high transient currents required
by the MOSFET gate drivers.
The EXTV
and control power from the output or another external
source during normal operation. Whenever the EXTV
pin is above 4.7V the internal 5V regulator is shut off and
an internal 50mA P-channel switch connects the EXTV
pin to INTV
until this pin drops below 4.5V. Do not apply more than
7V to the EXTV
following list summarizes the possible connections for
EXTV
1. EXTV
internal 5V regulator.
2. EXTV
supply compatible with the MOSFET gate drive require-
ments (typically 5V) can improve overall efficiency.
CC
:
CC
CC
CC
connected to an external supply. A high efficiency
grounded. INTV
CC
pin can be used to provide MOSFET gate drive
. INTV
CC
V
OUT1
C
OUT
pin and ensure that EXTV
C
V
SEC
1μF
OUT2
+
CC
+
power is supplied from EXTV
IN4148
CC
C
1:N
T1
IN
is always powered from the
+
PGND
V
IN
Figure 4. Secondary Output Loop and EXTV
10
11
12
13
14
15
16
1
2
3
4
5
6
7
8
9
PGND
PGND
PGND
SW
SW
SW
SW
SW
SW
SW
SW
PV
PV
PV
PV
PV
IN
IN
IN
IN
IN
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
17 18 19 20 21 22 23 24 25
CC
≤ V
IN
. The
CC
CC
CC
LTC3611
26 27 28 29 30 31 32
SW
SW
3. EXTV
The low voltage output can be boosted using a charge
pump or flyback winding to greater than 4.7V. The system
will start-up using the internal linear regulator until the
boosted output supply is available.
Soft-Start and Latchoff with the RUN/SS Pin
The RUN/SS pin provides a means to shut down the
LTC3611 as well as a timer for soft-start and overcurrent
latchoff. Pulling the RUN/SS pin below 0.8V puts the
LTC3611 into a low quiescent current shutdown (I
30μA). Releasing the pin allows an internal 1.2μA current
source to charge up the external timing capacitor C
RUN/SS has been pulled all the way to ground, there is a
delay before starting of about:
When the voltage on RUN/SS reaches 1.5V, the LTC3611
begins operating with a clamp on I
t
DELAY
CC
=
connected to an output derived boost network.
CC
1.2μA
1.5V
EXTV
PGOOD
Connection
SGND
SGND
SGND
SGND
SGND
SGND
SGND
SGND
V
SGND
FCB
RNG
V
V
I
I
ON
ON
CC
TH
FB
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
C
SS
3611 F04
SGND
= 1.3s/μF
R4
R3
OPTIONAL EXTV
CONNECTION
5V < V
(
OUT2
< 7V
CC
)
C
TH
SS
LTC3611
of approximately
15
SS
3611fb
Q
. If
<