參數(shù)資料
型號(hào)： TDA8924
廠商： NXP Semiconductors N.V.
英文描述： 2 x 120 W class-D power amplifier
中文描述： 2 × 120瓦D類功率放大器
文件頁(yè)數(shù)： 16/35頁(yè)
文件大?。?/td> 722K
代理商： TDA8924
2003 Jul 28
16
Philips Semiconductors
Objective specification
2
×
120 W class-D power amplifier
TDA8924
16.5
Heatsink requirements
Although the TDA8924 is a class-D amplifier a heatsink is
required. Reason is that though efficiency is high, the
output power is high as well, resulting in heating up of the
device. The relation between temperatures, dissipation
and thermal behaviour is given below.
P
diss
is determined by the efficiency (
η
) of the TDA8924.
The efficiency measured in the TDA8924 as a function of
output power is given in Figs. 17 and 18. The power
dissipationcanbederivedasfunction ofoutputpower;see
Figs. 15 and 16.
Thederatingcurves(givenforseveralvaluesoftheR
th(j-a)
)
are illustrated in Fig.8. A maximum junction temperature
T
j
= 150
°
Cistakenintoaccount.FromFig.8themaximum
allowable power dissipation for a given heatsink size can
bederivedortherequiredheatsinksizecanbedetermined
at a required dissipation level.
Example:
P
o
= 2
×
100 W into 2
T
j(max)
= 150
°
C
T
amb
= 60
°
C
P
diss(tot)
= 37 W (see Fig.15).
The required R
th(j-a)
= 2.43 K/W can be calculated.
The R
th(j-a)
of the TDA8924 in free air is 35 K/W; the R
th(j-c)
of the TDA8924 is 1.3 K/W, thus a heatsink of 1.13 K/W is
required for this example.
This example demonstrates that one might end up with
unrealistically low R
th(j-a)
figure. It has to be kept in mind
that in actual applications, other factors such as the
average power dissipation with a music source (as
opposedtoacontinuoussinewave)willdeterminethesize
of the heatsink required.
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
----------------------------
T
A
–
P
diss
=
handbook, halfpage
0
Pdiss
(W)
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) R
th(j-a)
= 5 K/W.
(2) R
th(j-a)
= 10 K/W.
(3) R
th(j-a)
= 15 K/W.
(4) R
th(j-a)
= 20 K/W.
(5) R
th(j-a)
= 35 K/W.
相關(guān)PDF資料
PDF描述
TDA8924TH 2 x 120 W class-D power amplifier
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TDA8924TH 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:2 x 120 W class-D power amplifier
TDA8924TH/N2,118 功能描述:IC AMP AUDIO PWR 240W D 24HSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機(jī)，2-通道（立體聲） 在某負(fù)載時(shí)最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點(diǎn):I²C，麥克風(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR)
TDA8925 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Power stage 2 x 15 to 25Wclass-D audio amplifier
TDA8925J 制造商:Panasonic Industrial Company 功能描述:IC
TDA8925J/N1,112 功能描述:IC AMP AUDIO PWR 20W STER 17SIL RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機(jī)，2-通道（立體聲） 在某負(fù)載時(shí)最大輸出功率 x 通道數(shù)量:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點(diǎn):I²C，麥克風(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR)
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