The power components (including input/output
capacitors, inductor, and TPS53318 or TPS53319 device) should be placed on one
side of the PCB (solder side). At least one inner plane should be inserted,
connected to ground, to shield and isolate the small signal traces from noisy
power lines.
All sensitive analog traces and components such
as VFB, PGOOD, TRIP, MODE, and RF should be placed away from high-voltage
switching nodes such as LL, VBST to avoid coupling. Use internal layer or layers
as ground plane or planes and shield feedback trace from power traces and
components.
Place the VIN decoupling capacitors as close to the VIN and PGND pins as possible to minimize the input AC current loop.
Because the TPS53319 device controls output
voltage referring to voltage across the VOUT capacitor, the top-side resistor of
the voltage divider should be connected to the positive node of the VOUT
capacitor. The GND of the bottom side resistor should be connected to the GND
pad of the device. The trace from these resistors to the VFB pin should be short
and thin.
Place the frequency setting resistor
(RF), OCP setting resistor (RTRIP), and mode setting
resistor (RMODE) as close to the device as possible. Use the common
GND via to connect them to GND plane if applicable.
Place the VDD and VREG decoupling capacitors as close to the device as possible. Ensure to provide GND vias for each decoupling capacitor and make the loop as small as possible.
For better noise filtering on VDD, a dedicated and localized decoupling support is strongly recommended.
The PCB trace defined as switch node, which connects the LL pins and high-voltage side of the inductor, should be as short and wide as possible.
Connect the ripple injection VOUT signal (VOUT side of the C1 capacitor in Figure 9-12) from the terminal of ceramic output capacitor. The AC coupling capacitor (C2 in Figure 9-12) should be placed near the device, and R7 and C1 can be placed near the power stage.
Use separated vias or trace to connect LL node to
snubber, boot strap capacitor, and ripple injection resistor. Do not combine
these connections.