LTC3728LX Linear Technology, LTC3728LX Datasheet - Page 26

• Manufacturer Part Number: LTC3728LX
• Description: 2-Phase Synchronous Regulators
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
LTC3728L/LTC3728LX
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 10. The Figure 11 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
within 1cm of each other with a common drain connection
at C
two channels as it can cause a large resonant loop.
26
IN
? Do not attempt to split the input decoupling for the
R1
R3
R2
R4
U
INTV
3.3V
Figure 10. LTC3728L/LTC3728LX Recommended Printed Circuit Layout Diagram
CC
U
f
IN
RUN/SS1
SENSE1
SENSE1
V
PLLFLTR
PLLIN
FCB
I
SGND
3.3V
I
V
SENSE2
SENSE2
LTC3728L/LTC3728LX
TH1
TH2
OSENSE1
OSENSE2
W
OUT
+
–
–
+
RUN/SS2
BOOST1
BOOST2
EXTV
PGOOD
INTV
PGND
SW1
SW2
BG1
BG2
TG1
TG2
V
U
CC
CC
IN
2. Are the signal and power grounds kept separate? The
combined IC signal ground pin and the ground return of
C
The path formed by the top N-channel MOSFET, Schottky
diode and the C
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.
3. Do the LTC3728L/LTC3728LX V
dividers connect to the (+) terminals of C
divider must be connected between the (+) terminal of
INTVCC
R
PGOOD
PU
C
C
C
B1
B2
INTVCC
must return to the combined C
V
(<7V)
PULL-UP
CERAMIC
C
IN
VIN
V
R
M1
M3
IN
IN
capacitor should have short leads and
1 F
CERAMIC
M2
M4
1 F
C
L1
L2
IN
R
www.DataSheet4U.com
R
SENSE
SENSE
C
C
OSENSE
OUT1
OUT2
D1
D2
OUT
OUT
3728 F10
? The resistive
pins’ resistive
(–) terminals.
V
GND
V
OUT1
OUT2
3728lxfa