TDA7497SA datasheet(6/10 Pages) STMICROELECTRONICS

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TDA7497SA

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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)

3.1 Example:

VCC = 28V, Rload = 8ohm (left/right), Rload = 4ohm (centre), RTh j-c = 2.5°C/W , Tamb max = 50°C

Pdmax = (N° channels) ·

Pdmax = 2 · ( 3.95 ) + 1 · ( 7.9 ) + 1.2 = 17W

(Heat Sinker)

In figure 6 is shown the Power derating curve for the device.

Figure 11. Power Derating Curve

load

⋅

------------------------------ I

⋅

Th c-a

150

amb max

–

d max

----------------------------------------- R

Th j-c

–

150

–

---------------------- 2.5

–

3.3

°C/W

Infinite Heatsink

1.5 °C/ W

3.0 °C/ W

5.0 °C/ W

(c)

(a)

(b)

(d)

040

120

160

Tamb (°C)

Infinite Heatsink

1.5 °C/ W

3.0 °C/ W

5.0 °C/ W

(c)

(a)

(b)

(d)

040

120

160

Tamb (°C)

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