Datasheet
www.ti.com
LAYOUT CONSIDERATIONS
THERMAL INFORMATION
ThetaJB:35 CW°
No Airflow
4
3.5
3
2.5
2
1.5
1
0.5
0
0 100 200 300 400 500 600 700 800 900 1000
PulseWidth-ms
SinglePulsePowerDisipation-W
t =85 C
PCB
°
TPS61050
TPS61052
SLUS525 – MARCH 2007
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 should 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, it is recommended to 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.
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.
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
Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where
high maximum power dissipation exists, special care must be paid to thermal dissipation issues in board design.
The maximum junction temperature (T
J
) of the TPS6105x is 150 ° C.
The maximum power dissipation gets especially critical when the device operates in the linear down mode at
high LED current. For single pulse power thermal analysis (e.g., flash strobe), the allowable power dissipation
for the device is given by Figure 48 .
Figure 48. Single Pulse Power Capability (CSP Package)
32
Submit Documentation Feedback