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参数资料
| 型号： | MAX9756ETX+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 11/31页 |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO PWR 2.3W AB 36TQFN |
| 标准包装： | 50 |
| 系列： | DirectDrive® |
| 类型： | AB 类 |
| 输出类型： | 2-通道（立体声）带立体声耳机 |
| 在某负载时最大输出功率 x 通道数量： | 2.3W x 2 @ 3 欧姆; 130mW x 2 @ 16 欧姆 |
| 电源电压： | 4.5 V ~ 5.5 V |
| 特点： | 消除爆音，短路保护和热保护，关机，音量控制 |
| 安装类型： | 表面贴装 |
| 供应商设备封装： | 36-TQFN 裸露焊盘（6x6） |
| 封装/外壳： | 36-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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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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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX9756ETX+ | 功能描述:音频放大器 Integrated Circuits (ICs) RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| MAX9756ETX+T | 功能描述:音频放大器 Integrated Circuits (ICs) RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| MAX9756EVKIT | 功能描述:放大器 IC 开发工具 Programmers, Development Systems RoHS:否 制造商:International Rectifier 产品:Demonstration Boards 类型:Power Amplifiers 工具用于评估:IR4302 工作电源电压:13 V to 23 V |
| MAX9757ETJ+ | 功能描述:音频放大器 Integrated Circuits (ICs) RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| MAX9757ETJ+T | 功能描述:音频放大器 Integrated Circuits (ICs) RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
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