Datasheet

LTC3862
32
3862fc
For more information www.linear.com/LTC3862
applicaTions inForMaTion
Figure 26a. A 5V to 36V Input, 48V/5A Output 2-Phase Boost Converter Application Circuit
Figure 26b. Output Current vs Input Voltage
The saturation current rating of the inductors must
therefore exceed:
I
n
I
D
L SAT
OMAX
MAX
()
()
••
.•
–
•
≥+






=
1
1
2
13
1
1
2
χ
11
04
2
13 5
10505
79+






=
.
•
.•
–.
.
A
A
The inductor value chosen was 18.7μH and the part
number is PB2020-223, manufactured by Pulse Engi-
neering. This inductor has a saturation current rating
of 20A.
8.
The power MOSFET chosen for this application is
a Renesas HAT2266H. This MOSFET has a typical
R
DS(ON)
of 11mΩ at V
GS
= 4.5V and 9.2mΩ at V
GS
= 10V. The BV
DSS
is rated at a minimum of 60V and
the maximum continuous drain current is 30A. The
typical gate charge is 25nC for a V
GS
= 4.5V. Last but
not least, this MOSFET has an absolute maximum
avalanche energy rating EAS of 34mJ, indicating that
it is capable of avalanche without catastrophic failure.
9. The total IC quiescent current, IC power dissipation
and maximum junction temperature are approximately:
I
Q(TOT)
= I
Q
+ 2 • Q
G(TOT)
• f
= 3mA + 2 • 25nC • 300kHz = 18mA
P
DISS
= 24V • 18mA = 432mW
T
J
= 70°C + 432mW • 34°C/W = 84.7°C
INPUT VOLTAGE (V)
0
1
0
OUTPUT LOAD CURRENT (A)
2
3
4
5
6
10 20 30 40
3862 F26b
SENSE1
+
3V8
SLOPE
BLANK
CLKOUT
SYNC
PLLFLTR
PHASEMODE
D
MAX
10nF
SENSE1
–
SENSE2
–
SENSE2
+
RUN
FREQ
SS
V
IN
45.3k 24.9k
84.5k
10Ω
V
IN
5V TO 36V
D1
30BQ060
D2
30BQ060
10Ω
L2
18.7µH
PB2020-223
ITH
SGND
V
OUT
12.4k
FB
30.1k
475k
10nF
1µF
1nF
6.8µF 50V
0.008Ω
1W
Q1
HAT2266H
Q2
HAT2266H
0.008Ω
1W
V
OUT
48V
5A (MAX)
3862 F26a
100µF
63V
100µF
63V
6.8µF 50V
6.8µF 50V
10µF ×4 50V
LTC3862
4.7nF
100pF
INTV
CC
GATE1
GATE2
PGND
4.7µF
10nF
10µF ×4 50V
10µF ×4 50V
10µF ×4 50V
L1
18.7µH
PB2020-223
+
+