V

IN

V

OUT

GND

L1

C1

C2

R1

R2

GND

TPS61220, TPS61221, TPS61222

SLVS776B – JANUARY 2009 – REVISED NOVEMBER 2014

www.ti.com

13 Layout

13.1 Layout Guidelines

As for all switching power supplies, the layout is an important step in the design, especially at high peak currents

and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as

well as EMI problems. Therefore, use wide and short traces for the main current path and for the power ground

paths. The input and output capacitor, as well as the inductor should be placed as close as possible to the IC.

The feedback divider in an application using the TPS61220 should be placed as close as possible to the control

ground pin of the IC. To route the ground path from the resistor divider, use short traces as well, separated from

the power ground traces. This avoids ground shift problems, which can occur due to superimposition of power

ground current and control ground current. Assure that the ground traces are connected close to the device GND

pin.

13.2 Layout Example

Figure 30. PCB Layout Suggestion For Adjustable Output Voltage Options

13.3 Thermal Considerations

Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires

special attention to power dissipation. Many system-dependent issues such as thermal coupling, airflow, added

heat sinks and convection surfaces, and the presence of other heat-generating components affect the power-

dissipation limits of a given component.

Three basic approaches for enhancing thermal performance are listed below.

•

Improving the power-dissipation capability of the PCB design

•

Improving the thermal coupling of the component to the PCB

•

Introducing airflow in the system

For more details on how to use the thermal parameters in the dissipation ratings table please check the Thermal

Characteristics Application Note (SZZA017) and the IC Package Thermal Metrics Application Note (SPRA953).

18

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