ltc3827ig-1 Linear Technology Corporation, ltc3827ig-1 Datasheet - Page 24

• Manufacturer Part Number: ltc3827ig-1
• Description: Low Iq, Dual, 2-phase Synchronous Step-down Controller
• Manufacturer: Linear Technology Corporation

APPLICATIO S I FOR ATIO
PC Board Layout Checklist
When laying out the printed circuit board, the following
checklist should be used to ensure proper operation of the
IC. These items are also illustrated graphically in the
layout diagram of Figure 11. Figure 12 illustrates the
current waveforms present in the various branches of the
2-phase synchronous regulators operating in the continu-
ous mode. Check the following in your layout:
1. Are the top N-channel MOSFETs M1 and M3 located
LTC3827-1
24
within 1cm of each other with a common drain con-
nection at C
decoupling for the two channels as it can cause a large
resonant loop.
IN
? Do not attempt to split the input
U
U
f
IN
Figure 11. LTC3827-1 Recommended Printed Circuit Layout Diagram
I
V
SENSE1
SENSE1
PLLLPF
PLLIN/MODE
SGND
RUN1
RUN2
SENSE2
SENSE2
V
I
TRACK/SS2
TH1
TH2
FB1
FB2
W
LTC3827-1
+
–
–
+
TRACK/SS1
PGOOD1
BOOST1
BOOST2
EXTV
INTV
PGND
SW1
SW2
U
TG1
BG1
BG2
TG2
V
CC
CC
IN
2. Are the signal and power grounds kept separate? The
3. Do the LTC3827-1 V
combined IC signal ground pin and the ground return
of C
nals. The path formed by the top N-channel MOSFET,
Schottky diode and the C
leads and PC trace lengths. The output capacitor (–)
terminals should be connected as close as possible to
the (–) terminals of the input capacitor by placing the
capacitors next to each other and away from the Schottky
loop described above.
to the (+) terminals of C
be connected between the (+) terminal of C
signal ground. The feedback resistor connections should
R
PGOOD1
PU
C
C
INTVCC
C
B2
B1
INTVCC
C
V
(<8.5V)
VIN
PULL-UP
must return to the combined C
CERAMIC
V
R
M1
M3
IN
IN
1μF
FB
CERAMIC
M2
pins’ resistive dividers connect
M4
OUT
1μF
L1
C
L2
IN
IN
capacitor should have short
? The resistive divider must
R
R
SENSE
SENSE
C
C
OUT1
OUT2
D1
D2
38271 F11
OUT
V
GND
V
(–) termi-
OUT1
OUT2
OUT
38271fd
and