TDA7491LP datasheet(32/37 Pages) STMICROELECTRONICS

32 / 37 page

Applications information

TDA7491LP

32/37

Doc ID 13541 Rev 5

5.9

Heatsink requirements

Due to the high efficiency of the class-D amplifier a 2-layer PCB can easily provide the

heatsinking capability for low to medium power outputs.

Using such a PCB with a copper ground layer of 3 x 3 cm2 and 16 vias connecting it to the

contact area for the exposed pad, a thermal resistance, junction to ambient (in natural air

convection), of 24 °C/W can be achieved.

The dissipated power within the device depends primarily on the supply voltage, load

impedance and output modulation level. With the TDA7491LP driving 2 x8

Ω with a supply

of 9 V then the maximum device dissipation is approximately 1 W.

When this power is dissipated at the maximum ambient temperature of 85 °C and the device

is mounted on the above PCB then the junction temperature could reach:

Tj = Tamb + Pd * Rj-amb = 85 + 1 * 24 = 109 °C

However, this temperature is sufficiently low to avoid triggering thermal warning.

With a musical program the dissipated power is about 40% less than the above maximum

value. This leads to a junction temperature of around only 99 °C with the 9 cm2 copper

ground. A commensurately smaller heatsink can thus be used.

Figure 36 shows the power derating curve for the PowerSSO-36 package on PCBs with

copper areas of 2 x 2 cm2 and 3 x 3 cm2.

Figure 36.

Power derating curves for PCB used as heatsink

100

120

140

160

Pd (W)

Tamb ( °C)

Copper Area 2x2 cm

and via holes

TDA7491P

PSSO36

Copper Area 3x3 cm

and via holes

TDA7491LP

PowerSSO-36

TDA7491LP 数据表(PDF) 32 Page - STMicroelectronics

TDA7491LP 数据表(HTML) 32 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37

数据表下载