Datasheet
LTC3823
21
3823fd
• Place C
IN
, C
OUT
, MOSFETs, D1 and inductor all in one
compact area. It may help to have some components
on the bottom side of the board.
• Use an immediate via to connect the components to
ground plane including SGND and PGND of LTC3823.
Use several bigger vias for power components.
• Use compact plane for switch node (SW) to improve
cooling of the MOSFETs and to keep EMI down.
• Use planes for V
IN
and V
OUT
to maintain good voltage
fi ltering and to keep power losses low.
• Flood all unused areas on all layers with copper. Flooding
with copper will reduce the temperature rise of power
component. You can connect the copper areas to any
DC net (V
IN
, V
OUT
, GND or to any other DC rail in your
system).
When laying out a printed circuit board, without a ground
plane, use the following checklist to ensure proper opera-
tion of the controller.
3823 F12
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
FCB
RUN
V
ON
PGOOD
V
RNG
V
FB
I
TH
SGND
I
ON
V
DIFFOUT
V
OUTSENSE
+
V
OUTSENSE
–
TRACK/SS
PLLFLTR
GND
PGOOD
V
RNG
INTV
CC
V
ITH
I
ON
DIFFOUT
FB
TRACK/SS
RUN
Z0
BOOST
TG
SW
SENSE
+
SENSE
–
PGND
BG
INTV
CC
Z2
Z1/SS
ENABLE
ZV
CC
V
IN
PLLIN
LTC3823GN
R6
7.5k
R5
42.5k
R
ON
100k
R2
16.2k
R1
5.11k
R
C
1.5k
R
PG
100k
C
C2
100pF
C
C1
6800pF
C4
220pF
C
SS
0.1μF
1000pF
10k
C
VCC
4.7μF
D
B
CMDSH-3
D1
B320A
+
C
OUT3
47μF
X5R
s3
C
OUT1
220μF
4V
V
OUT
2.5V
10A
V
IN
5V TO 28V
+
C
IN
10μF
50V
s3
C
B
0.22μF
R7
23.2k
R8
27.1k
M1
Si7342DP
L1
1.2μH
M2
Si7892ADP
PLLIN
+
0.01μF
Figure 12. Design Example: 2.5V/7A at 320kHz
• Segregate the signal and power grounds. All small-
signal components should return to the SGND pin at
one point which is then tied to the PGND pin close to
the source of M2.
• Place M2 as close to the controller as possible, keeping
the PGND, BG and SW traces short.
• Connect the input capacitor(s) C
IN
close to the power
MOSFETs. This capacitor carries the MOSFET AC
current.
• Keep the high dV/dt SW, BOOST and TG nodes away
from sensitive small-signal nodes.
• Connect the INTV
CC
decoupling capacitor C
VCC
closely
to the INTV
CC
and PGND pins.
• Connect the top driver boost capacitor C
B
closely to
the BOOST and SW pins.
• Connect the V
IN
pin decoupling capacitor C
IN
closely
to the V
IN
and PGND pins.
APPLICATIONS INFORMATION