LTC3127 Linear Technology, LTC3127 Datasheet - Page 15

• Manufacturer Part Number: LTC3127
• Description: 1A Buck-Boost DC/DC Converter
• Manufacturer: Linear Technology

PCB Layout Considerations
The LTC3127 switches large currents at high frequencies.
Special care should be given to the PCB layout to ensure
stable, noise-free operation. Figure 4 depicts the recom-
mended PCB layout to be utilized for the LTC3127. A few
key guidelines follow:
1. All circulating high current paths should be kept as short
2. The small-signal ground pad (SGND) should have a
applicaTions inForMaTion
as possible. This can be accomplished by keeping the
routes to all bold components in Figure 4 as short and
as wide as possible. Capacitor ground connections
should via down to the ground plane in the shortest
route possible. The bypass capacitor on V
placed as close to the IC as possible and should have
the shortest possible path to ground.
single point connection to the power ground. A con-
GROUND
VIA TO
MODE
SHDN
PROG
V
IN
Figure 4. Recommended PCB Layout
IN
1
2
3
4
5
SW1
should be
PGND
3. The components shown in bold and their connections
4. To prevent large circulating currents from disrupting
5. Use of vias in the die attach pad will enhance the ther-
6. Keep the connections to the FB and PROG pins as
venient way to achieve this is to short the pin directly
to the Exposed Pad as shown in Figure 4.
should all be placed over a complete ground plane.
the output voltage sensing, the ground for the resistor
divider and R
small signal ground pin (SGND).
mal environment of the converter especially if the vias
extend to a ground plane region on the exposed bottom
surface of the PCB.
short as possible and away from the switch pin con-
nections.
SW2
10
9
8
7
6
SGND
V
FB
C
V
OUT
PROG
GROUND
VIA TO
3127 F04
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LTC3127

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