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參數資料
| 型號： | TPA0242PWP |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 音頻控制 |
| 英文描述： | 2 CHANNEL(S), VOLUME CONTROL CIRCUIT, PDSO24 |
| 封裝： | GREEN, PLASTIC, HTSSOP-24 |
| 文件頁數： | 17/35頁 |
| 文件大小： | 806K |
| 代理商： | TPA0242PWP |
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Crest Factor and Thermal Considerations
P
dB + 10 Log
P
W
P
ref
+ 10 Log
4 W
1 W
+ 6 dB
(9)
TPA0242
SLOS287C – NOVEMBER 1999 – REVISED SEPTEMBER 2004
Table 3. Efficiency vs Output Power in 5-V, 8-
BTL Systems
EFFICIENCY
OUTPUT POWER (W)
PEAK VOLTAGE (V)
INTERNAL DISSIPATION (W)
(%)
0.25
31.4
2.00
0.55
0.50
44.4
2.83
0.62
1.00
62.8
4.00
0.59
1.25
70.2
4.47(1)
0.53
(1)
High peak voltages cause the THD to increase.
A final point to remember about Class-AB amplifiers (either SE or BTL) is how to manipulate the terms in the
efficiency equation to utmost advantage when possible. Note that in Equation 8, VDD is in the denominator. This
indicates that as VDD goes down, efficiency goes up.
Class-AB power amplifiers dissipate a significant amount of heat in the package under normal operating
conditions. A typical music CD requires 12 dB to 15 dB of dynamic range, or headroom, above the average
power output, to pass the loudest portions of the signal without distortion. In other words, music typically has a
crest factor between 12 dB and 15 dB. When determining the optimal ambient operating temperature, the internal
dissipated power at the average output power level must be used. From the data sheet, one can see that when
the device is operating from a 5-V supply into a 3-
speaker that 4-W peaks are available. Use Equation 9 to
convert watts to dB.
Subtracting the headroom restriction to obtain the average listening level without distortion yields:
6 dB - 15 dB = -9 dB (15-dB crest factor)
6 dB - 12 dB = -6 dB (12-dB crest factor)
6 dB - 9 dB = -3 dB (9-dB crest factor)
6 dB - 6 dB = 0 dB (6-dB crest factor)
6 dB - 3 dB = 3 dB (3-dB crest factor)
Converting dB back into watts:
PW = 10
PdB/10
× P
ref
= 63 mW (18-dB crest factor)
= 125 mW (15-dB crest factor)
= 250 mW (9-dB crest factor)
= 500 mW (6-dB crest factor)
= 1000 mW (3-dB crest factor)
= 2000 mW (0-dB crest factor)
This is valuable information to consider when estimating the heat-dissipation requirements for the amplifier
system. Comparing the worst case, 2 W of continuous power output with a 3-dB crest factor, against 12-dB and
15-dB applications, drastically affects maximum ambient temperature ratings for the system. Using the power
dissipation curves for a 5-V, 3-
system, the internal dissipation and maximum ambient temperatures are shown
in the table below.
24
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相關代理商/技術參數 |
參數描述 |
|---|---|
| TPA0242PWPG4 | 功能描述:音頻放大器 2W Stereo RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TPA0242PWPR | 功能描述:音頻放大器 St 2W Aud Pwr Amp RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TPA0242PWPRG4 | 功能描述:音頻放大器 St 2W Aud Pwr Amp RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TPA0243 | 制造商:TI 制造商全稱:Texas Instruments 功能描述:2-W MONO AUDIO POWER AMPLIFIER WITH HEADPHONE DRIVE |
| TPA0243DGQ | 功能描述:音頻放大器 2W Mono Aud Pwr Amp RoHS:否 制造商:STMicroelectronics 產品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
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