ltc3770 Linear Technology Corporation, ltc3770 Datasheet - Page 22

• Manufacturer Part Number: ltc3770
• Description: Fast No Rsense Step-down Synchronous Controller With Margining, Tracking And Pll
• Manufacturer: Linear Technology Corporation

APPLICATIO S I FOR ATIO
TYPICAL APPLICATIO
LTC3770
When laying out a printed circuit board, without a ground
plane, use the following checklist to ensure proper opera-
tion of the controller.
• Segregate the signal and power grounds. All small
• Place M2 as close to the controller as possible, keeping
• Connect the input capacitor(s) C
22
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.
the PGND, BG and SW traces short.
220pF
TRACK/SS
C
PGOOD
F
RUN
R2
60.4k
R1
30.1k
R
51k
RUN
R
10k
100pF
C
CC1
1000pF
CC2
47k
51k
R7
R8
U
MARGIN1
MARGIN0
10k
R
75k
R
100k
R5
PG
ON
U
1
2
3
4
5
6
7
8
V
V
I
SGND
MARGIN1
MARGIN0
I
V
TH
ON
V
RNG
FB
REFIN
REFOUT
9
U
PGOOD V
W
IN
MPGM TRACK/SS
32
10
close to the power
R6
200k
ON
31
RUN FCB
11
30
1.8V/5A at 450kHz with Tracking
LTC3770EUH
FCB
PLLFLTR PLLIN V
U
29
12
Z0 BOOST TG
28
13
27
IN
14
26
V
INSNS
V
5V
SW
CC
15
25
• Keep the high dV/dt SW, BOOST and TG nodes away
• Connect the INTV
• Connect the top driver boost capacitor C
• Connect the V
SENSE+
SENSE–
INTV
DRV
PGND
ZV
MOSFETs. This capacitor carries the MOSFET AC
current.
from sensitive small-signal nodes.
to the INTV
BOOST and SW pins.
the V
BG
Z2
Z1
IN
CC
CC
16
24
23
22
21
20
19
18
17
IN
and PGND pins.
1000pF
CC
IN
and PGND pins.
L1: BI TECH 1.8µH HM65-H1R8-TB
M1, M2: PHILIPS PH3230
C
C
pin decoupling capacitor C
IN
OUT
CC
: TDK C4532X5R1H685M
: PANASONIC EEFUE0G181R
decoupling capacitor C
CB
0.22µF
DB
CMDSH-3
CV
4.7µF
INTV
CC
CC
B340A
M1
PH3230
M2
PH3230
1.8µH
D1
L1
C
22µF
X5R
x2
OUT3
+
B
closely to the
C
180µF
4V
x2
IN
3770 TA02a
V
1.8V
5A
OUT
VCC
OUT
closely to
closely
C
6.8µF
50V
x3
V
4V TO 28V
IN
IN
3770fb