Datasheet

19
LTC1775
Figure 11. 5V/10A Fixed Output from Design Example
A short circuit to ground will result in a folded back
current of:
I
mV V s
H
A
SC
=
Ω
+






µ
µ
=
80
0 013 1 1
1
2
15 0 5
6
62
(. )(.)
()(.)
.
with a typical value of R
DS(ON)
and ρ(50°C) = 1.1. The
resulting power dissipated in the bottom MOSFET is:
P
VV
V
AW
BOT
=Ω=
15 5
15
62 11 0013 037
2
–
(. )(.)(. ) .
which is less than under full load conditions.
C
SS
0.1µF
R
C
10k
C
C1
2.2nF
C
C2
220pF
M1
SUD50N03-10
C
IN
22µF
30V
×4
V
OUT
5V
10A
M2
SUD50N03-10
D1
MBRS340
D
B
CMDSH-3
C
VCC
4.7µF
1775 F11
V
IN
TK
EXTV
CC
LTC1775
SYNC
V
PROG
SW
TG
BOOST
INTV
CC
BG
RUN/SS
FCB
I
TH
SGND
V
OSENSE
PGND
1
V
OUT
2
3
4
5
INTV
CC
6
7
8
16
15
14
13
12
11
10
9
C
B
0.33µF
R
F
1Ω
V
IN
6V TO 22V
L1
6µH
+
+
C
F
0.1µF
+
C
OUT
680µF
6.3V
+
C
IN
: SANYO 30SC22M
C
OUT
: SANYO 6SP680M
L1: MAGENTICS 55380-A2, 8 TURNS, 15 GAUGE
C
IN
is chosen for an RMS current rating of at least 5A at
temperature. C
OUT
is chosen with an ESR of 0.013Ω for
low output ripple. The output ripple in continuous mode
will be highest at the maximum input voltage and is
approximately:
∆V
O
= (∆I
L(MAX)
)(ESR) = (4.3A)(0.013Ω) = 56mV
The complete circuit is shown in Figure 11.
APPLICATIO S I FOR ATIO
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