Circuit Board Copper Area

50

40

30

20

10

0

0

1

2

3

4

5

OPA551, OPA552

Surface-Mount Package

1oz. copper

OPA551, OPA552

SBOS100B – JULY 1999 – REVISED JANUARY 2016

www.ti.com

10.5 Heat Sinking

Power dissipated in the OPA551 or OPA552 causes the junction temperature to rise. For reliable operation, limit

the junction temperature to 125°C. Many applications require a heatsink to assure that the maximum operating

junction temperature is not exceeded. The heatsink required depends on the power dissipated and on ambient

conditions.

For heatsinking purposes, the tab of the DDPAK/TO-263 is typically soldered directly to the PCB copper area.

Increasing the copper area improves heat dissipation. Figure 38 shows typical thermal resistance from junction-

to-ambient as a function of copper area.

Depending on conditions, additional heatsinking may be required. Aavid Thermal Products Inc. manufactures

surface-mountable heatsinks designed specifically for use with DDPAK/TO-263 packages. Further information is

available on the Aavid web site, www.aavid.com.

To estimate the margin of safety in a complete design (including heatsink), increase the ambient temperature

until the thermal protection is activated. Use worst-case load and signal conditions. For good reliability, the

thermal protection must trigger more than 25°C above the maximum expected ambient condition of your

application. This level produces a junction temperature of 125°C at the maximum expected ambient condition.

Figure 38. Thermal Resistance vs Circuit Board Copper Area

Figure 39. OPA551, OPA552 Surface-Mount Package Circuit Board Copper Area

20

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