SA7454

than:

(150

°C－50°C)/6W＝16.7°C/W

For HSIP-9 package, the die-to-package thermal resistance is Rth(j-c) = 8

°C/W，then the package-to-ambient

thermal resistance should be lower than 8.7

°C/W. So we need heat sink to reduce the package-to-ambient

thermal resistance.

For DIP-18IH-300-2.54 package, the die-to-package thermal resistance is Rth(j-c) = 15

°C/W ， then the

package-to-ambient thermal resistance should be lower than 1.7

°C/W，that will make heat sinking difficult, in

addition, DIP-18IH-300-2.54 can not add effective heat sink, so we need to reduce the power dissipation by

reducing load. For example, with a 8

Ω load, it can develop up to 3W of internal power dissipation, and the

package-to-ambient thermal resistance should be lower than:

(150

°C－50°C)/3W－15°C/W＝18.3°C /W

The thermal requirements can become more difficult when SA7454 is driving a reactive load. As a general rule,

the power dissipation of an amplifier driving a 60º reactive load (usually considered to be a worst-case

loudspeaker load) will be roughly that of the same amplifier driving the resistive part of that load. For example, a

loudspeaker may at some frequency have an impedance with a magnitude of 8

Ω and a phase angle of 60º. The

real part of this load will then be 4

Ω, and the amplifier power dissipation equal to the power dissipation with a 4Ω

load.

TYPICAL APPLICATION CIRCUIT

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

REV:1.0

2008.10.21

Http://www.silan.com.cn

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