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參數(shù)資料
| 型號： | MAX9752CETI+T |
| 廠商： | Maxim Integrated Products |
| 文件頁數(shù)： | 6/29頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC AMP AUDIO PWR 1.7W D 28TQFN |
| 標(biāo)準(zhǔn)包裝： | 2,500 |
| 系列： | DirectDrive® |
| 類型： | D 類 |
| 輸出類型： | 2-通道（立體聲）帶立體聲耳機 |
| 在某負(fù)載時最大輸出功率 x 通道數(shù)量： | 1.7W x 2 @ 4 歐姆; 62mW x 2 @ 16 歐姆 |
| 電源電壓： | 4.5 V ~ 5.5 V |
| 特點： | 消除爆音，短路保護和熱保護，關(guān)機，音量控制 |
| 安裝類型： | 表面貼裝 |
| 供應(yīng)商設(shè)備封裝： | 28-TQFN-EP（5x5） |
| 封裝/外殼： | 28-WFQFN 裸露焊盤 |
| 包裝： | 帶卷 (TR) |
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MAX9752/MAX9753/MAX9754
Headphone Amplifier
DirectDrive
Conventional single-supply headphone amplifiers have
their outputs biased about a nominal DC voltage (typi-
cally half the supply) for maximum dynamic range.
Large coupling capacitors are needed to block the DC
bias from the headphones.
Maxim’s DirectDrive architecture uses a charge pump to
create an internal negative supply voltage. This allows the
MAX9752/MAX9753/MAX9754 headphone amplifier out-
put to be biased about GND, almost doubling the dynam-
ic range, while operating from a single supply. With no DC
component, there is no need for the large DC-blocking
capacitors. Instead of two large capacitors (220F, typ),
the charge pump requires only two small ceramic capaci-
tors (1F typ), conserving board space, reducing cost,
and improving the frequency response of the headphone
amplifier. See the Output Power vs. Charge-Pump
Capacitance and Load Resistance graph in the Typical
Operating Characteristics for details of the possible
capacitor values.
Previous attempts to eliminate the output-coupling capac-
itors involved biasing the headphone return (sleeve) to
the DC bias voltage of the headphone amplifiers. This
method raised some issues:
1) The sleeve is typically grounded to the chassis. Using
this biasing approach, the sleeve must be isolated
from system ground, complicating product design.
2) During an ESD strike, the amplifier’s ESD structures
are the only path to system ground. The amplifier
must be able to withstand the full ESD strike.
3) When using the headphone jack as a line out to
other equipment, the bias voltage on the sleeve
may conflict with the ground potential from other
equipment, resulting in large ground-loop current
and possible damage to the amplifiers.
Low-Frequency Response
In addition to the cost and size disadvantages, the DC-
blocking capacitors limit the low-frequency response of
the amplifier and distort the audio signal:
1) The impedance of the headphone load and the DC-
blocking capacitor form a highpass filter with the
-3dB point determined by:
where RL is the impedance of the headphone and
COUT is the value of the DC-blocking capacitor.
The highpass filter is required by conventional single-
ended, single-supply headphone amplifiers to block
the midrail DC component of the audio signal from
the headphones. Depending on the -3dB point, the
filter can attenuate low-frequency signals within the
audio band. Larger values of COUT reduce the atten-
uation, but are physically larger, more expensive
capacitors. Figure 6 shows the relationship between
the size of COUT and the resulting low-frequency
attenuation. Note the -3dB point for a 16
Ω head-
phone with a 100F blocking capacitor is 100Hz, well
within the audio band.
2) The voltage coefficient of the capacitor, the change in
capacitance due to a change in the voltage across
the capacitor, distorts the audio signal. At frequen-
cies around the -3dB point, the reactance of the
capacitor dominates, and the voltage coefficient
appears as frequency-dependent distortion. Figure 7
shows the THD+N introduced by two different
capacitor dielectrics. Note that around the -3dB point,
THD+N increases dramatically.
The combination of low-frequency attenuation and
frequency-dependent distortion compromises audio
reproduction. DirectDrive improves low-frequency
reproduction in portable audio equipment that
emphasizes low-frequency effects such as multi-
media laptops, MP3, CD, and DVD players.
f
RC
dB
L OUT
=
3
1
2
π
2.2W, Low-EMI, Stereo, Class D Power Amplifiers
with DirectDrive Headphone Amplifiers
14
______________________________________________________________________________________
0
-15
10
100
1k
10k
100k
LOW-FREQUENCY ROLLOFF
(RL = 16
Ω)
-12
-6
-9
-3
FREQUENCY (Hz)
ATTENUATION
(dB)
DirectDrive
330
μF
220
μF
100
μF
33
μF
Figure 6. Low-Frequency Attenuation of Common DC-Blocking
Capacitor Values
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| MAX9753ETI+ | 功能描述:音頻放大器 Integrated Circuits (ICs) 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 |
| MAX9753ETI+T | 功能描述:音頻放大器 Integrated Circuits (ICs) 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 |
| MAX9754ETI+ | 功能描述:音頻放大器 Integrated Circuits (ICs) 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 |
| MAX9754ETI+T | 功能描述:音頻放大器 Integrated Circuits (ICs) 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 |
| MAX9755ETI+ | 功能描述:音頻放大器 Integrated Circuits (ICs) 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 |
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