Datasheet

LTC3865/LTC3865-1
33
3865fb
APPLICATIONS INFORMATION
A short-circuit to ground will result in a folded back cur-
rent of:
I
mV
ns V
H
SC
=
()
Ωμ
⎛
⎝
⎜
⎞
⎠
⎟
=
1350
0008
1
2
90 20
33
/
.
–
()
.
11 8.A
with a typical value of R
DS(ON)
and δ = (0.005/°C)(20)
= 0.1. The resulting power dissipated in the bottom
MOSFET is:
P
VV
V
A
m
SYNC
=
()( )
Ω
()
=
20 3 3
20
1 8 1 125 0 016
48
2
–.
...
WW
which is less than under full-load conditions.
C
IN
is chosen for an RMS current rating of at least 2A at
temperature assuming only channel 1 or 2 is on. C
OUT
is
chosen with an ESR of 0.02Ω for low output ripple. The
output ripple in continuous mode will be highest at the
maximum input voltage. The output voltage ripple due to
ESR is approximately:
V
ORIPPLE
= R
ESR
(ΔI
L
) = 0.02Ω(1.5A) = 30mV
P-P
0.1µF
L2
0.47µH
Q1
RJK0305DPB
Q3
RJK0305DPB
Q4
RJK0330DPB
D2
Q2
RJK0330DPB
1000pF
1000pF 1000pF
22µF
50V
10k
V
OUT1
1.5V
15A
0.1µF
L2
0.47µH
1000pF
C
OUT4
100µF
15k
162k
1%
V
OUT2
1.2V
15A
TG1 TG2
BOOST1 BOOST2
SW1 SW2
BG1
BG2
SGND
PGND
FREQ
SENSE1
+
SENSE2
+
RUN2
SENSE1
–
SENSE2
–
V
OSENSE1
V
OSENSE2
I
TH1
I
TH2
V
IN
PGOOD INTV
CC
TK/SS1 TK/SS2
V
IN
4.5V TO 24V
3865 F16
0.1µF
100pF
0.1µF
LTC3865
10µF
35V
10µF
35V
MODE/PLLIN
I
LIM
RUN1
VID11
VID12
VID21
VID22
EXTV
CC
4.7µF
C
OUT1
100µF
C
OUT2,3
100pF
100Ω
100Ω
100Ω
100Ω
2.2Ω
1µF
D4D3
D1, D2: VISHAY B340A
L1, L2: VISHAY IHLP4040DZERR47M11
C
OUT1
, C
OUT4
: TDK C322JX5R0J107MT
C
OUT2
, C
OUT3
, C
OUT5
, C
OUT6
: SANYO 4TPE 220µF
2mΩ
2mΩ
+
C
OUT5,6
+
+
D1
Figure 16. 1.5V/15A, 1.2V/15A Converter Using Sense Resistors
TYPICAL APPLICATIONS