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参数资料
| 型号： | TDA8920TH/N1,118 |
| 厂商： | NXP SEMICONDUCTORS |
| 元件分类： | 音频／视频放大 |
| 英文描述： | 80 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO24 |
| 封装： | PLASTIC, SOT-566-3, HSOP-24 |
| 文件页数： | 9/36页 |
| 文件大小： | 733K |
| 代理商： | TDA8920TH/N1,118 |
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2002 Sep 25
17
Philips Semiconductors
Product specication
2
× 80 W class-D power amplier
TDA8920
16.5
Heatsink requirements
In some applications it may be necessary to connect an
external heatsink to the TDA8920TH. The determining
factor is the 150
°C maximum junction temperature
[Tj(max)] which cannot be exceeded. The expression below
shows the relationship between the maximum allowable
power dissipation and the total thermal resistance from
junction to ambient:
Pdiss is determined by the efficiency (η) of the 1-chip
class-D amplifier. The efficiency measured in the
TDA8920TH as a function of output power is given in
Fig.18. The power dissipation can be derived as function
of output power; see Fig.17.
The derating curves (given for several values of the Rth(j-a))
are illustrated in Fig.8. A maximum junction temperature
Tj = 150 °C is taken into account. From Fig.8 the maximum
allowable power dissipation for a given heatsink size can
be derived or the required heatsink size can be determined
at a required dissipation level.
Example 1:
Pout =2 × 30 W into 8
Tj(max) = 150 °C
Tamb =60 °C
Pdiss(tot) = 6 W (from Fig.17)
The required Rth(j-a) = 15 K/W can be calculated
The Rth(j-a) of TDA8920 in free air is 35 K/W; the Rth(j-c) of
TDA8920 is 1.3 K/W, thus a heatsink of 13.7 K/W is
required for this example.
In actual applications, other factors such as the average
power dissipation with music source (as opposed to a
continuous sine wave) will determine the size of the
heatsink required.
Example 2:
Pout =2 × 75 W into 4
Tj(max) = 150 °C
Tamb =60 °C
Pdiss(tot) = 17.5 W (from Fig.17)
The required Rth(j-a) = 5.14 K/W
The Rth(j-a) of TDA8920TH in free air is 35 K/W; the Rth(j-c)
of TDA8920TH is 1.3 K/W, so a heatsink of 3.84 K/W is
required for this example.
16.6
Output current limiting
To guarantee the robustness of the class-D amplifier the
maximum output current which can be delivered by the
output stage is limited. An overcurrent protection is
included for each output power switch. When the current
flowing through any of the power switches exceeds a
defined internal threshold (e.g. in case of a short-circuit to
the supply lines or a short-circuit across the load), the
amplifier will shut down immediately and an internal timer
will be started. After a fixed time (e.g. 100 ms) the amplifier
is switched on again. If the requested output current is still
too high the amplifier will switch-off again. Thus the
amplifier will try to switch to the operating mode every
100 ms. The average dissipation will be low in this
situation because of this low duty cycle. If the overcurrent
condition is removed the amplifier will remain operating.
Because the duty cycle is low the amplifier will be switched
off for a relatively long period of time which will be noticed
as a so-called audio-hole; an audible interruption in the
output signal.
R
th(j-a)
T
j(max)
T
A
–
P
diss
-----------------------------
=
handbook, halfpage
0
Pdiss
(W)
30
20
10
0
20
100
Tamb (°C)
40
(1)
(2)
(3)
(4)
(5)
60
80
MBL469
Fig.8 Derating curves for power dissipation as a
function of maximum ambient temperature.
(1) Rth(j-a) = 5 K/W.
(2) Rth(j-a) =10K/W.
(3) Rth(j-a) =15K/W.
(4) Rth(j-a) = 20 K/W.
(5) Rth(j-a) = 35 K/W.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TDA8922 | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:2 x 25 W class-D power amplifier |
| TDA8922B | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:2 X 50 W class-D power amplifier |
| TDA8922BJ | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:2 X 50 W class-D power amplifier |
| TDA8922BJ/N2,112 | 功能描述:音频放大器 2X50W CLASSD PWR AMP RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| TDA8922BTH | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:2 X 50 W class-D power amplifier |
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