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參數資料
| 型號： | TPA301DG4 |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | 0.7 W, 1 CHANNEL, AUDIO AMPLIFIER, PDSO8 |
| 封裝： | GREEN, PLASTIC, MS-012AA, SOIC-8 |
| 文件頁數： | 10/28頁 |
| 文件大小： | 765K |
| 代理商： | TPA301DG4 |
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Midrail Bypass Capacitor, CB
10
C
B
250 k
v
1
R
F )
R
I
C
I
(10)
USING LOW-ESR CAPACITORS
5-V VERSUS 3.3-V OPERATION
HEADROOM AND THERMAL CONSIDERATIONS
P
dB +
10LogP
W +
10Log 3500 mW + –4.6 dB
TPA301
SLOS208E – JANUARY 1998 – REVISED JUNE 2004
The midrail bypass capacitor, CB, is the most critical capacitor and serves several important functions. During
start-up or recovery from shutdown mode, CB determines the rate at which the amplifier starts up. The second
function is to reduce noise produced by the power supply caused by coupling into the output drive signal. This
noise is from the midrail generation circuit internal to the amplifier, appearing as degraded PSRR and THD + N.
The capacitor is fed from a 250-k
source inside the amplifier. To keep the start-up pop as low as possible, the
relationship shown in Equation 10 should be maintained, which ensures the input capacitor is fully charged
before the bypass capacitor is fully charged and the amplifier starts up.
As an example, consider a circuit where CB is 2.2 F, CI is 0.47 F, RF is 50 k and RI is 10 k. Inserting these
values into the Equation 10 we get: 18.2
≤ 35.5, which satisfies the rule. Recommended values for bypass
capacitor CB are 2.2 F to 1 F, ceramic or tantalum low-ESR, for the best THD and noise performance.
Low-ESR capacitors are recommended throughout this application. A real (as opposed to ideal) capacitor can be
modeled simply as a resistor in series with an ideal capacitor. The voltage drop across this resistor minimizes the
beneficial effects of the capacitor in the circuit. The lower the equivalent value of this resistance, the more the
real capacitor behaves like an ideal capacitor.
The TPA301 operates over a supply range of 2.5 V to 5.5 V. This data sheet provides full specifications for 5-V
and 3.3-V operation, as these are considered to be the two most common standard voltages. There are no
special considerations for 3.3-V versus 5-V operation with respect to supply bypassing, gain setting, or stability.
The most important consideration is that of output power. Each amplifier in TPA301 can produce a maximum
voltage swing of VDD– 1 V. This means, for 3.3-V operation, clipping starts to occur when VO(PP) = 2.3 V as
opposed to VO(PP) = 4 V at 5 V. The reduced voltage swing subsequently reduces maximum output power into an
8-
load before distortion becomes significant.
Operation from 3.3-V supplies, as can be shown from the efficiency formula in Equation 4, consumes
approximately two-thirds the supply power for a given output-power level than operation from 5-V supplies.
Linear 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 headroom to pass the loudest portions without distortion
as compared with the average power output. From the TPA301 data sheet, one can see that when the TPA301
is operating from a 5-V supply into a 8-
speaker, 350-mW peaks are available. Converting watts to dB:
Subtracting the headroom restriction to obtain the average listening level without distortion yields:
–4.6 dB – 15 dB = –19.6 dB (15 dB headroom)
–4.6 dB – 12 dB = –16.6 dB (12 dB headroom)
–4.6 dB – 9 dB = –13.6 dB (9 dB headroom)
–4.6 dB – 6 dB = –10.6 dB (6 dB headroom)
–4.6 dB – 3 dB = –7.6 dB (3 dB headroom)
18
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相關代理商/技術參數 |
參數描述 |
|---|---|
| TPA301DGH | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| TPA301DGN | 功能描述:音頻放大器 0.35W Mono 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 |
| TPA301DGNG4 | 功能描述:音頻放大器 0.35-W Mono Audio Power Amplifier 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 |
| TPA301DGNR | 功能描述:音頻放大器 0.35-W Mono Audio Power Amplifier 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 |
| TPA301DGNRG4 | 功能描述:音頻放大器 0.35-W Mono Audio Power Amplifier 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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