SLVS978D March 2010 – September 2016 TPS61310 , TPS61311
PRODUCTION DATA.
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 tracks.
The input capacitor, output capacitor, and the inductor must be placed as close as possible to the IC. Use a common ground node for power ground and a different one for control ground to minimize the effects of ground noise. Connect these ground nodes at any place close to one of the ground pins of the IC.
To lay out the control ground, TI recommends using short traces which are 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.
Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires special attention to power dissipation. Many system-dependant 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.
There are three basic approaches for enhancing thermal performance:
Junction-to-ambient thermal resistance is highly dependent on application and board layout. In applications where high maximum power dissipation exists, thermal dissipation issues in board design must be considered. The maximum junction temperature (TJ) of the TPS6131x is 150°C.
The maximum power dissipation is especially critical when the device operates in the linear down mode at high LED current. For single-pulse power thermal analysis, such as during a flash strobe, the allowable power dissipation for the device is given by Figure 73. These values are derived using the reference design.