TDF8599B NXP Semiconductors, TDF8599B Datasheet - Page 36

• Manufacturer Part Number: TDF8599B
• Description: The TDF8599B is a dual Bridge-Tied Load (BTL) car audio amplifier comprising anNDMOST-NDMOST output stage based on SOI BCDMOS technology
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TDF8599B_1
Product data sheet
14.4 Speaker configuration and impedance
14.5 Heat sink requirements
A flat-frequency response (due to a 2
the low-pass filter components (L
impedance.
Table 22.
Remark: When using a 1
after the low-pass filter switches two 2
In most applications, it is necessary to connect an external heat sink to the TDF8599B.
Thermal foldback activates at T
between the maximum power dissipation before activation of thermal foldback and the
total thermal resistance from junction to ambient:
P
function of output power is given in
function of output power (see
Example 1:
The total thermal resistance R
Where:
If an audio signal has a crest factor of 10 (the ratio between peak power and average
power = 10 dB) then T
R
Load impedance ( )
1
2
4
max
•
•
•
•
•
•
•
•
•
th j-a
V
P
T
T
P
The required R
Thermal resistance from junction to case (R
Thermal resistance from case to heat sink (R
mounting)
Thermal resistance from heat sink to ambient (R
19
is determined by the efficiency ( ) of the TDF8599B. The efficiency measured as a
j(max)
amb
P
o
max
= 2
= 14.4 V
=
(1 + 1) = 17 K/W.
= 25 C
= 5.8 W (from
T
----------------------------------- - K W
Filter component values
= 140 C
j max
Table 22
25 W into 4
P
max
–
T
th(j-a)
amb
shows the required values.
j
will be much lower.
Rev. 01 — 29 July 2009
Figure
= 115 C / 5.8 W = 19 K/W
(THD = 10 % continuous)
load impedance in Parallel mode, the outputs are shorted
I
Figure
2
L
2.5
5
10
th(j-a)
42)
C-bus controlled dual channel class-D power amplifier
j
LC
= 140 C. The expression below shows the relationship
LC
( H)
consists of: R
, C
Figure
42).
nd
LC
order Butterworth filter) is obtained by changing
) based on the speaker configuration and
filters in parallel.
43. The power dissipation can be derived as a
th(j-c)
th(c-h)
th(j-c)
) = 1 K/W
th(h-a)
) = 0.5 K/W to 1 K/W (depending on
+ R
th(c-h)
) would then be
C
4.4
2.2
1
LC
+ R
( F)
th(h-a)
TDF8599B
© NXP B.V. 2009. All rights reserved.
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