Datasheet

LTC3883/LTC3883-1
55
3883fa
For more information www.linear.com/LTC3883
Figure 26. Recommended Printed Circuit Layout Diagram
Figure 27. Branch Current Waveforms
LTC3883
GND
I
IN_SNS
I
SENSE
+
I
SENSE
–
V
IN
V
DD25
V
DD33
I
TH
V
SENSE
–
V
SENSE
+
RUN
SYNC
TSNS
TG
SW
BOOST
BG
GND
INTV
CC
V
IN_SNS
C1
R
IIN
R
IIN
V
IN
R
IINSNS
+
Q1
L
M1
1µF
CERAMIC
C
B
3883 F26
C
IN
+
C
INTVCC
M2
D1
C
OUT
V
OUT
R
SENSE
+
C
VIN
R
VIN
R
L
D
L
SW
R
SENSE
V
OUT
C
OUT
R
SENSEIN
V
IN
C
IN
R
IN
BOLD LINES INDICATE
HIGH SWITCHING
CURRENT. KEEP LINES
TO A MINIMUM LENGTH.
CURRENT WAVFORM
AT NODE
3883 F27
the IC. Ensure accurate current sensing with Kelvin
connections at the sense resistor or inductor, whichever
is used for current sensing.
4. 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 driver current peaks.
An additional 1µF ceramic capacitor placed immediately
next to the INTV
CC
and PGND pins can help improve
noise performance substantially.
APPLICATIONS INFORMATION
5. Keep the switching node (SW), top gate node (TG), and
boost node (BOOST) away from sensitive small-signal
nodes, especially from the voltage and current sensing
feed-back pins. All of these nodes have very large and
fast moving signals and therefore should be kept on the
“output side” of the LTC3883 and occupy minimum PC
trace area. If DCR sensing is used, place the top resistor
(Figure 18a, R1) close to the switching node.