DocID023949 Rev 2

7/19

AN4209

STRVS parameters

the die to the ambient, via all paths. Its value is strongly dependent on the type of board, the

copper plane underneath the device, the neighboring components interacting through the

PCB, and the mounting and cooling methods (free or forced airflow).

Actual performance of the product in real applications may be different. Values provided in

datasheet are typical values and should be used with some measure of caution. It is useful

for comparing the thermal performance of one package to another as shown in Table 1.

Therefore, this information may be used for the first pass of junction temperature

package over copper plane area.

Figure 5. Junction-to-ambient thermal resistance over copper plane area of SMB

package

the die to the package lead. This parameter is useful for estimating the junction temperature

from a measurement of the lead temperature. The designer can determine the lead

temperature of the device under application conditions with a fine gauge thermocouple or

Table 1. Typical package performance comparison for minimum footprint and 35 µm

copper thickness on board

Thermal resistance

Package

Unit

DO-15

DO-201

SMB

SMC

35

23

13

12

°C/W

105

100

185

150

°C/W

0

20

40

60

80

100

120

140

160

180

200

01234

56789

10

Rth(j-a) (°C/W)

Copper surface (cm2)