STK403-430 Sanyo, STK403-430 Datasheet - Page 5

• Manufacturer Part Number: STK403-430
• Description: 6-Channel Class AB Audio Power Amplifier IC
• Manufacturer: Sanyo

Thermal Design Example
The heat sink thermal resistance, c-a, required to handle the total power dissipated within this hybrid IC is determined as
follows.
We take the power dissipation in the power transistors to be Pd evenly distributed across those N power transistors.
If we solve for c-a in equations (1) and (2), we get the following inequalities.
Values that satisfy both these inequalities at the same time are the required heat sink thermal resistance values.
Determining the following specifications allows us to determine the required heat sink thermal resistance from
inequalities (1)’ and (2)’.
Example:
Assume that the IC supply voltage, V
from the Pd – P
For actual music signals, it is usual to use a Pd of 1/8 of P
this manner. (Note that depending on the particular safety standard used, a value somewhat different from the value of
1/8 used here may be used.)
The number, N, of power transistors in the hybrid IC's audio amplifier block is 12. Since the thermal resistance, c-a, per
transistor is 3.6°C/W, the required heat sink thermal resistance, c-a, for a guaranteed ambient temperature of 50°C will
be as follows.
Therefore, the thermal resistance that satisfies both these expressions at the same time is 1.15°C/W.
Note that this thermal design example assumes the use of a constant-voltage power supply, and is only provided as an
example for reference purposes. Thermal designs must be tested in an actual end product.
Condition 1: The IC substrate temperature Tc must not exceed 125°C.
Condition 2: The junction temperature of each individual transistor must not exceed 150°C.
• Supply voltage: V
• Load resistance: R
• Guaranteed ambient temperature: Ta
That is:
Pd
Ta: Guaranteed ambient temperature for the end product.
Pd
N: Number of power transistors
Pd = 65 W (when 1/8 P
From inequality (1)’: c – a < (125 – 50)/65
From inequality (2)’: c – a < (150 – 50)/65 – 3.6/12
j-c: Thermal resistance per power transistor
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
O
characteristics, the maximum power will be 103 W for a signal with a frequency of 1 kHz.
CC
L
j – c + Ta < 150°C ... (2)
O
max is 2.5 W)
< 1.15
< 1.23
CC
, is ±23 V, R
STK403-430
L
is 6 Ω, and that the signal is a continuous sine wave. In this case,
O
max, which is the power estimated for continuous signals in
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