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STK4142II Datasheet, PDF (8/8 Pages) Sanyo Semicon Device – AF Power Amplifier (Split Power Supply) | |||
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STK4142II
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 = 23.6W at 8â¦, Pd = 28.2W at 4â¦
Thermal resistance θc-a of a heat sink for this IC power dissipation (Pd) is ï¬xed under conditions 1 and 2 shown below.
Condition 1: Tc = Pd à θc-a + Ta ⤠125°C............................................... (1)
where Ta : Speciï¬ed ambient temperature
Tc : Operating substrate temperature
Condition 2: Tj= Pd à (θc-a) + Pd/4 à (θc-a) + 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 à 2), thermal resis-
tance θj-c is 2.6°C/W and
Pd à (θc-a + 2.6/4) + 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-
ï¬ed for a stereo ampliï¬er is 50°C.
Assuming VCC = ±26V, RL = 8â¦,
VCC = ±22V, RL = 4â¦,
RL = 8⦠: Pd1 = 23.6W at 1/10 Po max.
RL = 4⦠: Pd2 = 28.2W at 1/10 Po max.
The thermal resistance of a heat sink is
obtained from Figure 3.
RL = 8⦠: θc-a1 = 3.18°C/W
RL = 4⦠: θc-a2 = 2.66°C/W
Tj when a heat sink is used is obtained from
(3).
RL = 8⦠: Tj = 140.4°C
RL = 4⦠: Tj = 143.4°C
IC Power dissipation, Pd - W
Figure 3. STK4142II θc-a â Pd
s 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.
s Anyone purchasing any products described or contained herein for an above-mentioned use shall:
 Accept full responsibility and indemnify and defend SANYO ELECTRIC CO., LTD., its afï¬liates, subsidiaries and distributors and all their
ofï¬cers and employees, jointly and severally, against any and all claims and litigation and all damages, cost and expenses associated
with such use:
 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 afï¬liates, subsidiaries and distributors or any of their ofï¬cers and employees, jointly or severally.
s 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. Speciï¬cations and information herein are subject to change without notice.
No. 2665â8/8
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