TDA7494SA datasheet(10/13 Pages) STMICROELECTRONICS

10 / 13 page

TDA7496SA

10/13

HEAT SINK DIMENSIONING:

In order to avoid the thermal protection intervention, that is placed approximatively at Tj = 150°C, it is important

the dimensioning of the Heat Sinker RTh (°C/W).

The parameters that influence the dimensioning are:

– Maximum dissipated power for the device (Pdmax)

– Max thermal resistance Junction to case (RTh j-c)

– Max. ambient temperature Tamb max

– Quiescent current Iq (mA)

Example:

VCC = 22V, Rload = 8ohm, RTh j-c = 5 °C/W , Tamb max = 50°C

Pdmax = (N° channels) ·

Pdmax = 2 · ( 3.0 ) + 0.5 = 6.5 W

(Heat Sinker)

In figure 23 is shown the Power derating curve for the device.

Figure 23. Power derating curve

lo ad

⋅

------------------------------

⋅

Th c-a

150

am b max

–

d max

-----------------------------------------

Th j-c

–

150

–

6.5

----------------------

5.0

–

°C/W

Infinite Heatsink

7 °C/ W

10 °C/ W

(c)

(a)

(b)

120

160

Tamb (°C)

Infinite Heatsink

7 °C/ W

10 °C/ W

(c)

(a)

(b)

120

160

Tamb (°C)

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