Datasheet

LTC3838-1
41
38381f
For more information www.linear.com3838-1
APPLICATIONS INFORMATION
DTR2 RUN2
LTC3838-1
SENSE2
–
SENSE2
+
V
DFB2
–
V
DFB2
+
ITH2
V
RNG
R
ITH2(2)
C
ITH1(2)
C
ITH2(2)
C
SS2
LOCALIZED
SGND TRACE
PGOOD2 BOOST2
DTR1 RUN1SENSE1
–
SENSE1
+
PGOOD1 BOOST1
TG2
C
B2
D
B2
D
B1
R
INTVCC
SW2
DRV
CC2
EXTV
CC
V
IN
DRV
CC1
BG1
SW1
TG1
PGND
INTV
CC
BG2
C
INTVCC
C
VIN
R
VIN
C
DRVCC
C
B1
C
IN
CERAMIC
CERAMIC
MT2
MB2
MT1
MB1
+
V
IN
L2
L1
38381 F14
C
OUT2
V
OUT2
PGND
V
OUT1
BOLD LINES INDICATE HIGH SWITCHING CURRENT. KEEP LINES TO A MINIMUM LENGTH
+
C
OUT1
+
R
SENSE1
R
SENSE2
RT
R
T
TRACK/SS2
MODE/PLLIN
CLKOUT
SGND
PHASMD
R
ITH1(2)
R
DFB1
//R
DFB2
C
ITH2(1)
C
ITH1(1)
C
SS1
R
FB1(1)
R
ITH1(1)
ITH1
TRACK/SS1
V
OUTSENSE1
+
V
OUTSENSE1
–
R
ITH2(1)
R
FB2(1)
R
DFB2
R
DFB1
Figure 14. Recommended PCB Layout Diagram
• Keep small-signal components connected noise-sensi-
tive pins (give priority to SENSE
+
/SENSE
–
, V
OUTSENSE1
+
/
V
OUTSENSE1
–
, V
DFB2
+
/V
DFB2
–
, RT, ITH, V
RNG
pins) on
the left hand side of the IC as close to their respective
pins as possible. This minimizes the possibility of noise
coupling into these pins. If the LTC3838-1 can be placed
on the bottom side of
a multilayer board, use ground
planes to isolate from the major power components on
the top side of the board, and prevent noise coupling
to noise sensitive components on the bottom side.
• Place the resistor feedback dividers close to the
V
OUTSENSE1
+
and V
OUTSENSE1
–
pins for channel 1,
or V
DFB2
+
and V
DFB2
–
pins for channel 2, so that the
feedback voltage tapped from the resistor divider will
not be disturbed by noise sources. Route remote sense
PCB traces (use a pair of wires closely together for
differential sensing) directly to the terminals of output
capacitors for
best output regulation.
• Place decoupling capacitors C
ITH2
next to the ITH and
SGND pins with short, direct trace connections.