參數(shù)資料
型號(hào)： MAX9756ETX+
廠商： Maxim Integrated Products
文件頁(yè)數(shù)： 11/31頁(yè)
文件大?。?/td> 0K
描述： IC AMP AUDIO PWR 2.3W AB 36TQFN
標(biāo)準(zhǔn)包裝： 50
系列： DirectDrive®
類(lèi)型： AB 類(lèi)
輸出類(lèi)型： 2-通道（立體聲）帶立體聲耳機(jī)
在某負(fù)載時(shí)最大輸出功率 x 通道數(shù)量： 2.3W x 2 @ 3 歐姆; 130mW x 2 @ 16 歐姆
電源電壓： 4.5 V ~ 5.5 V
特點(diǎn)： 消除爆音，短路保護(hù)和熱保護(hù)，關(guān)機(jī)，音量控制
安裝類(lèi)型： 表面貼裝
供應(yīng)商設(shè)備封裝： 36-TQFN 裸露焊盤(pán)（6x6）
封裝/外殼： 36-WFQFN 裸露焊盤(pán)
包裝： 管件
Maxim’s DirectDrive architecture uses a charge pump to
create an internal negative supply voltage. This allows the
MAX9756/MAX9757/MAX9758 headphone amplifier out-
put to be biased at GND, almost doubling the dynamic
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 MAX9756/MAX9757/MAX9758 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 graph in the
Typical Operating Characteristics for details of the possi-
ble capacitor values.
Low-Frequency Response
In addition to the cost and size disadvantages, the DC-
blocking capacitors limit the low-frequency response of
the amplifier. 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 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 attenuation but are
physically larger, more expensive capacitors. Figure 10
shows the relationship between the size of COUT and
the resulting low-frequency attenuation. Note that the
-3dB point for a 16
Ω headphone with a 100F-blocking
capacitor is 100Hz, well within the audio band.
Charge Pump
The MAX9756/MAX9757/MAX9758 feature a low-noise
inverting charge pump to generate the negative rail
necessary for DirectDrive headphone operation. The
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 tran-
sients. Limiting the switching speed of the charge
pump minimizes the di/dt noise caused by the parasitic
bond wire and trace inductance.
Headphone Sense Input (HPS)
The headphone sense input (HPS) monitors the head-
phone jack and automatically configures the MAX9756/
MAX9757/MAX9758 based upon the voltage applied at
HPS. A voltage of less than 0.8V enables the speaker
amplifier. A voltage of greater than 2V disables the
speaker amplifiers and enables the headphone ampli-
fiers. For automatic headphone detection, connect HPS
to the control pin of a 3-wire headphone jack as shown
in Figure 11. With no headphone present, the output
impedance of the headphone amplifier pulls HPS low.
When a headphone plug is inserted into the jack, the
control pin is disconnected from the tip contact and
HPS is pulled to VDD with 35A.
fdB
RC
L OUT
=
3
1
2
π
MAX9756/MAX9757/MAX9758
2.3W Stereo Speaker Amplifiers and DirectDrive
Headphone Amplifiers with Automatic Level Control
______________________________________________________________________________________
19
0
-15.0
10
100
1k
10k
100k
LOW-FREQUENCY ROLLOFF
(RL = 16
Ω)
-12.0
-13.5
-6.0
-7.5
-9.0
-10.5
-3.0
-4.5
-1.5
FREQUENCY (Hz)
ATTENUATION
(dB)
DirectDrive
330
μF
220
μF
100
μF
33
μF
Figure 10. Low-Frequency Attenuation of Common DC-
Blocking Capacitor Values
MAX9756/
MAX9757/
MAX9758
14k
Ω
35
μA
14k
Ω
VDD
HPS
HPL
HPR
SHUTDOWN
CONTROL
Figure 11. HPS Configuration
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX9756ETX+ 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(lèi)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
MAX9756ETX+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(lèi)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
MAX9756EVKIT 功能描述:放大器 IC 開(kāi)發(fā)工具 Programmers, Development Systems RoHS:否 制造商:International Rectifier 產(chǎn)品:Demonstration Boards 類(lèi)型:Power Amplifiers 工具用于評(píng)估:IR4302 工作電源電壓:13 V to 23 V
MAX9757ETJ+ 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(lèi)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
MAX9757ETJ+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(lèi)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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