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參數(shù)資料
| 型號： | MAX9750BETI+T |
| 廠商： | Maxim Integrated Products |
| 文件頁數(shù)： | 5/30頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC AMP AUDIO PWR 2.6W AB 28TQFN |
| 標準包裝： | 2,500 |
| 系列： | DirectDrive® |
| 類型： | AB 類 |
| 輸出類型： | 2-通道（立體聲）帶立體聲耳機 |
| 在某負載時最大輸出功率 x 通道數(shù)量： | 2.6W x 2 @ 3 歐姆; 110mW 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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MAX9750/MAX9751/MAX9755
2.6W Stereo Audio Power Amplifiers and
DirectDrive Headphone Amplifiers
______________________________________________________________________________________
13
significant amount of DC current flows to the headphone,
resulting in unnecessary power dissipation and possible
damage to both headphone and headphone amplifier.
Maxim’s DirectDrive architecture uses a charge pump to
an internal negative supply voltage. This allows the
MAX9750/MAX9751/MAX9755 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 MAX9750/MAX9751/MAX9755 charge pump requires
only two small ceramic capacitors (1F typ), conserving
board space, reducing cost, and improving the frequen-
cy 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 val-
ues.
Previous attempts to eliminate the output coupling
capacitors 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 lineout to other
equipment, the bias voltage on the sleeve may con-
flict 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 to the DC-
blocking capacitor forms 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 sin-
gle-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
attenuation but are physically larger, more expen-
sive capacitors. Figure 3 shows the relationship
between the size of COUT and the resulting low-fre-
quency attenuation. Note that the -3dB point for a
16
Ω headphone 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
frequencies around the -3dB point, the reactance of
the capacitor dominates, and the voltage coefficient
appears as frequency-dependent distortion. Figure
4 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 fre-
quency-dependent distortion compromises audio
reproduction. DirectDrive improves low-frequency
reproduction in portable audio equipment that empha-
sizes low-frequency effects such as multimedia lap-
tops, and MP3, CD, and DVD players.
Charge Pump
The MAX9750/MAX9751/MAX9755 feature a low-noise
charge pump. The 550kHz switching frequency is well
beyond the audio range, and does not interfere with the
audio signals. The switch drivers feature a controlled
switching speed that minimizes noise generated by turn-
on and turn-off transients. Limiting the switching speed of
the charge pump minimizes the di/dt noise caused by the
f
RC
dB
L OUT
=
3
1
2
π
0
-30
10
100
1k
10k
100k
LOW-FREQUENCY ROLLOFF
(RL = 16
Ω)
-24
-27
-12
-15
-18
-21
-6
-9
-3
FREQUENCY (Hz)
ATTENUATION
(dB)
DirectDrive
330
μF
220
μF
100
μF
33
μF
Figure 3. Low-Frequency Attenuation of Common DC-Blocking
Capacitor Values
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PDF描述 |
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| VE-2ND-MY | CONVERTER MOD DC/DC 85V 50W |
| MAX9750CETI+T | IC AMP AUDIO PWR 2.6W AB 28TQFN |
| VE-230-CU-F1 | CONVERTER MOD DC/DC 5V 200W |
| VE-2NB-MY | CONVERTER MOD DC/DC 95V 50W |
| MAX9705CEBC+T | IC AMP AUDIO PWR 2.3W D 12UCSP |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX9750BEUI | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX9750CETI+ | 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: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX9750CETI+C2U | 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: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX9750CETI+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: 安裝風格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX9750CEUI | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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