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參數(shù)資料
| 型號： | TPA4411RTJ |
| 廠商： | Texas Instruments, Inc. |
| 英文描述： | 80-mW CAPLESS STEREO HEADPHONE DRIVER |
| 中文描述： | 80兆瓦的無蓋立體聲耳機驅(qū)動器 |
| 文件頁數(shù)： | 13/21頁 |
| 文件大?。?/td> | 859K |
| 代理商： | TPA4411RTJ |
www.ti.com
APPLICATION INFORMATION
Headphone Amplifiers
For single-supply headphone amplifiers, the output architecture typically require dc-blocking capacitors to remove
the mid-rail bias required to obtain symmetrical output voltage swing. These capacitors are required because
most headphone jacks are ground-referenced, with respect to the shield pin. Without the capacitors, there would
be a dc bias voltage across the headphone speakers. In Figure 64, the first block diagram and waveform
illustrate the traditional headphone amplifier connection to the headphone jack and output signal.
f
1
2 R C
(1)
C
O
1
2 R
L
fc
OUT
(2)
Input-Blocking Capacitors
DC input-blocking capacitors are required to be added in series with the audio signal into the input pins of the
TPA4411. These capacitors block the dc portion of the audio source and allow the TPA4411 inputs to be
properly biased to provide maximum performace.
fc
IN
1
2 R
IN
C
IN
Where R
IN
= 15 k
.
C
IN
1
2 fc
IN
R
IN
or
(3)
TPA4411
SLOS430–AUGUST 2004
These capacitors are typically large in value in order to prevent the filtering of the output audio signal. The
dc-blocking capacitors form a high-pass filter with the load impedance of the headphone speakers. Treating the
headphone speakers as a resistive load, typically either 16
or 32
, the dc-blocking capacitors form a
high-pass filter with the load impedance. Equation 1 shows the relationship between the load impedance (R), the
capacitor (C), and the cutoff frequency.
Substituting for the values in the circuit, the dc-blocking capacitors can be determined using Equation 2, where
the load impedance and the cutoff frequency are known.
From Equation 2, the capacitor must have a large value because the resistance value is small. Large
capacitance values require large package sizes which consume board area, increase cost of the assembly, and
can reduce the fidelity of the audio output signal.
Two different capless headphone amplifier applications are available that allow for the removal of the output
dc-blocking capacitors. The first amplifier architecture is implemented in the same manner as the traditional
amplifier with the exception of the headphone jack shield pin. This amplifier provides a reference voltage, which
is connected to the headphone jack shield pin. This is the voltage on which the audio output signals are
centered. This voltage reference is typically half of the amplifier power supply because this allows symmetrical
swing of the output voltages. The second block diagram and waveform shows the mid-supply biased capless
headphone architecture.
The second amplifier architecture operates from a single supply but makes use of an internal charge pump to
provide a negative voltage rail. Using this negative supply, the headphone amplifier is now a split supply amplifier
(internally) and can be considered a ground-reference amplifier. The output voltages are now centered at zero
volts with the capability to swing to the positive rail or negative rail. The bottom block diagram and waveform of
Figure 64 illustrate the ground-referenced capless headphone architecture.
These capacitors form a high-pass filter with the input impedance of the TPA4411. The cutoff frequency is
calculated using Equation 1. For this calculation, the capacitance used is input-blocking capacitor and the
resistance is the input impedance of the TPA4411. Because the gain of the TPA4411 is fixed, the input
impedance remains a constant value. Using the input impedance value from the operating characteristics table
and Equation 2, the frequency and/or capacitance can be determined when one of the two values are given.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPA4411RTJR | 功能描述:音頻放大器 80mW Cap-free Stereo Headphone Driver RoHS:否 制造商:STMicroelectronics 產(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TPA4411RTJRG4 | 功能描述:音頻放大器 80mW Cap-free Stereo Headphone Driver RoHS:否 制造商:STMicroelectronics 產(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TPA4411RTJT | 功能描述:音頻放大器 80mW Cap-free Stereo Headphone Driver RoHS:否 制造商:STMicroelectronics 產(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TPA4411RTJTG4 | 功能描述:音頻放大器 80mW Cap-free Stereo Headphone Driver RoHS:否 制造商:STMicroelectronics 產(chǎn)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(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| TPA4411YZH | 制造商:TI 制造商全稱:Texas Instruments 功能描述:80-mW CAPLESS STEREO HEADPHONE DRIVER |
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