STK400-010 Sanyo Semiconductor Corporation, STK400-010 Datasheet - Page 4

• Manufacturer Part Number: STK400-010
• Description: 3-channel (10W+10W+10W) af Power Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

Heatsink Design Considerations
The heatsink thermal resistance, c-a, required to dissipate
the STK400-010 device total power dissipation, Pd, is de-
termined as follows :
Condition 1: IC substrate temperature not to exceed 125 C
Where Ta is the guaranteed maximum ambient tempera-
ture.
Condition 2: Power transistor junction temperature, Tj, not
where N is the number of power transistors and j-c is the
power transistor thermal resistance per transistor. Note that
the power dissipated per transistor is the total, Pd, devided
evenly among the N power transistors.
Expressions (1) and (2) can be rewritten making c-a the
subject.
The heatsink required must have a thermal resistance that
simultaneously satisfied both expressions.
The heatsink thermal resistance can be determined from
(1)’ and (2)’ once the following parameters have been de-
fined.
• Supply voltage : V
• Load resistance : R
• Guaranteed maximum ambient temperature : Ta
Pd
Pd
c-a< (125–Ta)/Pd ............................................ (1)’
c-a< (150–Ta)/Pd– j-c/N ................................ (2)’
c-a+Ta<125 C ............................................ (1)
c-a+Pd/N
to exceed 150 C
CC
L
j-c+Ta<150 C ......................... (2)
STK400-010
The total device power dissipation when STK400-010
V
nal, is a maximum of 29.8W, as shown in the “Pd–P
acteristics graph.
When estimating the power dissipation for an actual audio
signal input, the rule of thumb is to select Pd correspond-
ing to (1/10) P
sine wave input. For example,
The STK400-010 has 6 power transistors, and the thermal
resistance per transistor, j-c, is 2.6 C/W. If the graranteed
maximum ambient temperature, Ta, is 50 C, then the re-
quired heatsink thermal resistance, c-a, is :
From expression (1)’ : c-a < (125–50)/16.8
From expression (2)’ : c-a < (150–50)/16.8–2.6/6
Therefore, to satisfy both expressions, the required heatsink
must have a thermal resistance less than 4.46 C/W.
Similarly, when STK400-010 V
From expression (1)’ : c-a < (125–50)/18.9
From expression (2)’ : c-a < (150–50)/18.9–2.6/6
Therefore, to satisfy both expressions, the required heatsink
must have a thermal resistance less than 3.97 C/W.
The heatsink design example is based on a constant-volt-
age supply, and should be verified within your specific set
environment.
CC
Pd=16.8W [for (1/10)
Pd=18.9W [for (1/10)
= 17V and R
O
max (within safe limits) for a continuous
L
=6 , for a continuous sine wave sig-
P
< 4.46
< 5.52
P
< 3.97
< 4.86
O
O
max=1W]
max=1W]
CC
= 14V and R
No.5246–4/6
L
=3 ,
O
” char-