tfa9843aj NXP Semiconductors, tfa9843aj Datasheet - Page 13

• Manufacturer Part Number: tfa9843aj
• Description: Tfa9843aj 20 W Stereo Power Amplifier With Volume Control
• Manufacturer: NXP Semiconductors

Philips Semiconductors
TFA9843AJ_1
Preliminary data sheet
13.3 Thermal behavior and heatsink calculation
The measured maximum thermal resistance of the IC package, R
A calculation for the heatsink can be made, with the following parameters:
R
heatsink. This can be calculated using the maximum temperature increase divided by the
power dissipation:
At V
8.4 W; see
dissipation, is: 150
This calculation is for an application at worst case (stereo) sine wave output signals. In
practice music signals will be applied, which decreases the maximum power dissipation to
approximately half of the sine wave power dissipation; see
use of a smaller heatsink:
th(tot)
T
V
T
R
P
R
R
P
R
R
amb(max)
j(max)
CC
th(tot)
th(tot)
th(h-a)
th(tot)
th(h-a)
CC
R
R
= 18 V and R
is the total thermal resistance between the junction and the ambient including the
= 18 V and R
th(tot)
th(tot)
= 150 C (specification)
= (T
= 90/8.4 K/W = 10.7 K/W
= 90/4.2 K/W = 21.4 K/W
= R
= R
Figure
= 60 C (example)
= 90 C
= 90 C
j(max)
th(tot)
th(tot)
8. For T
R
R
L
T
L
60 = 90 C:
= 4
amb(max)
th(j-mb)
th(j-mb)
= 4
Rev. 01 — 28 April 2006
j(max)
(SE)
= 10.7 K/W
= 21.4 K/W
(2
)/P
= 150 C the temperature raise, caused by the power
SE) the measured worst case sine wave dissipation is
20 W stereo power amplifier with volume control
2.0 K/W = 8.7 K/W
2.0 K/W = 19.4 K/W
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Section
TFA9843AJ
th(j-mb)
8.2.2. This allows the
, is 2.0 K/W.
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