Datasheet
LTC3707-SYNC
26
3707sfa
1. Are the top N-channel MOSFETs M1 and M3 located
within 1cm of each other with a common drain connection
at C
IN
? Do not attempt to split the input decoupling for
the two channels as it can cause a large resonant loop.
2. Are the signal and power grounds kept separate? The
combined IC signal ground pin and the ground return
of C
INTVCC
must return to the combined C
OUT
(–) terminals.
The path formed by the top N-channel MOSFET, Schottky
diode and the C
IN
capacitor should have short 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.
3. Do the IC V
OSENSE
pins resistive dividers connect to
the (+) terminals of C
OUT
? The resistive divider must be
APPLICATIONS INFORMATION
connected between the (+) terminal of C
OUT
and signal
ground. The R2 and R4 connections should not be along
the high current input feeds from the input capacitor(s).
4. Are the SENSE
–
and SENSE
+
leads routed together with
minimum PC trace spacing? The fi lter capacitor between
SENSE
+
and SENSE
–
should be as close as possible to the
IC. Ensure accurate current sensing with Kelvin connections
at the SENSE resistor.
5. Is the INTV
CC
decoupling capacitor connected close to
the IC, between the INTV
CC
and the power ground pins?
This capacitor carries the MOSFET drivers current peaks.
An additional 1μF ceramic capacitor placed immediately
next to the INTV
CC
and PGND pins can help improve noise
performance substantially.
Figure 10. LTC3707-SYNC Recommended Printed Circuit Layout Diagram
C
B2
C
B1
R
PU
PGOOD
V
PULL-UP
(<7V)
C
INTVCC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
+
C
IN
D1
M1 M2
M3 M4
D2
+
C
VIN
V
IN
R
IN
INTV
CC
3.3V
R4R3
R2
R1
RUN/SS1
SENSE1
+
SENSE1
–
V
OSENSE1
PLLFLTR
PLLIN
FCB
I
TH1
SGND
3.3V
OUT
I
TH2
V
OSENSE2
SENSE2
–
SENSE2
+
PGOOD
TG1
SW1
BOOST1
V
IN
BG1
EXTV
CC
INTV
CC
PGND
BG2
BOOST2
SW2
TG2
RUN/SS2
LTC3707-SYNC
L1
L2
C
OUT1
V
OUT1
GND
V
OUT2
3707 F10
+
C
OUT2
+
R
SENSE
R
SENSE
f
IN