LTC1735-1 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1735-1' PDF : 28 Pages View PDF
LTC1735-1
APPLICATIO S I FOR ATIO
LTC1735-1. The VOSENSE line should not be routed
close to any other nodes with high slew rates.
3. Are the SENSE + and SENSE – leads routed together with
minimum PC trace spacing? The filter capacitor be-
tween SENSE + and SENSE – should be as close as
possible to the LTC1735-1. Ensure accurate current
sensing with kelvin connections to the SENSE resistors
shown in Figure 13. Series resistance can be added to
the SENSE lines to increase noise rejection.
4. Does the (+) terminal of CIN connect to the drain of the
topside MOSFET(s) as closely as possible? This capaci-
tor provides the AC current to the MOSFET(s).
5. Is the INTVCC decoupling capacitor connected closely
between INTVCC and the power ground pin? This capaci-
tor carries the MOSFET driver peak currents. An addi-
tional 1µF ceramic placed immediately next to the INTVCC
and PGND pins can help improve noise performance.
6. 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
feedback pins. All of these nodes have very large and
fast moving signals and therefore should be kept on the
“output side” (Pins 9 to 16) of the LTC1735-1 and
occupy minimum PC trace area.
INTVCC
+
COSC
1
COSC
16
TG
Q1
CSS
2
RUN/SS
15
BOOST
RC
CC
3
14
ITH LTC1735-1 SW
CIN
CC2
4
PGOOD
13
VIN
DB
CB
VIN
5 SENSE –
1000pF 6 SENSE +
47pF
7
VOSENSE
8
SGND
12
INTVCC
11
BG
10
PGND
9
EXTVCC
+
4.7µF
D1
Q2
–
R1
COUT
R2
L1
RSENSE
–
VOUT
+
1735-1 F12
Figure 12. LTC1735-1 Layout Diagram
HIGH CURRENT PATH
1735-1 F13
SENSE + SENSE –
CURRENT SENSE
RESISTOR
(RSENSE)
Figure 13. Kelvin Sensing RSENSE
25
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