STK4172II

No. 2323—8/8

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No products described or contained herein are intended for use in surgical implants, life-support systems, aerospace equipment, nuclear

power control systems, vehicles, disaster/crime-prevention equipment and the like, the failure of which may directly or indirectly cause injury,

death or property loss.

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Anyone purchasing any products described or contained herein for an above-mentioned use shall:

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Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its affiliates, subsidiaries and distributors and all their

officers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associated

with such use:

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Not impose any responsibility for any fault or negligence which may be cited in any such claim or litigation on SANYO ELECTRIC CO.,

LTD., its affiliates, subsidiaries and distributors or any of their officers and employees, jointly or severally.

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Information (including circuit diagrams and circuit parameters) herein is for example only; it is not guaranteed for volume production. SANYO

believes information herein is accurate and reliable, but no guarantees are made or implied regarding its use or any infringements of

intellectual property rights or other rights of third parties.

This catalog provides information as of July, 1997. Specifications and information herein are subject to change without notice.

In an actual application where a music signal is used, it is impractical to estimate the power dissipation based on the con-

tinuous signal as shown above, because too large a heat sink must be used. It is reasonable to estimate the power dissipa-

tion as 1/10 Po max. (EIAJ).

That is, Pd = 35W at 8

Ω, Pd = 49W at 4Ω

Thermal resistance

θc-a of a heat sink for this IC power dissipation (Pd) is fixed under conditions 1 and 2 shown below.

Condition 1: Tc = Pd

× θc-a + Ta ≤ 125°C............................................... (1)

where

Ta : Specified ambient temperature

Tc : Operating substrate temperature

Condition 2: Tj= Pd

× (θc-a) + Pd/4 × (θj-c) + Ta ≤ 150°C..................... (2)

where

Tj : Junction temperature of power transistor

Assuming that the power dissipation is shared equally among the four power transistors (2 channels

× 2), thermal resis-

tance

θj-c is 1.8°C/W and

Pd

× (θc-a + 1.8/4) + Ta ≤ 150°C........................................ (3)

Thermal resistance

θc-a of a heat sink must satisfy ine-

qualities (1) and (3).

Figure 3 shows the relation between Pd and

θc-a given

from (1) and (3) with Ta as a parameter.

[Example] The thermal resistance of a heat sink is

obtained when the ambient temperature speci-

fied for a stereo amplifier is 50

°C.

The thermal resistance of a heat sink is

obtained from Figure 3.

Tj when a heat sink is used is obtained from

(3).

Figure 3. STK4172II

IC Power dissipation, Pd - W