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| 型号： | MAX9742ETX+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/36页 |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO PWR 20.5W D 36TQFN |
| 标准包装： | 50 |
| 类型： | D 类 |
| 输出类型： | 2 通道（立体声） |
| 在某负载时最大输出功率 x 通道数量： | 20.5W x 2 @ 8 欧姆 |
| 电源电压： | 20 V ~ 40 V，±10 V ~ 20 V |
| 特点： | 消除爆音，差分输入，静音，短路和热保护，关机 |
| 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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Bootstrap Diode (DBOOT)
To provide sufficient gate drive voltage to the high-side
transistor of the half-bridge output stage, an external
diode (DBOOT) and capacitor (CBOOT) are needed for
the internal bootstrapping circuitry (see Figure 2). To
maintain high power efficiencies and maximum output
power at low audio frequencies, use fast-recovery
switching diodes for DBOOT. Silicon diodes equivalent
to 1N914, BAS16, or 1N4148 work well.
Capacitor (CBOOT)
For most applications, use a CBOOT capacitor ≥ 0.1F
and ≤ 0.22F. For proper operation, use capacitors with
low ESR and voltage ratings greater than 7V for CBOOT.
Output-Coupling Capacitors
(COUT, Single-Ended, Single-Supply Operation)
The MAX9742 requires output-coupling capacitors for
single-supply operation. Since the MAX9742 outputs
switch between VDD and ground in single-supply opera-
tion, there is a DC component equal to 0.5 x VDD pre-
sent at the outputs. The output-coupling capacitor
blocks this DC component, preventing DC current from
flowing into the load. The output capacitor and the load
resistance of the speaker form a highpass filter. The
-3dB point of the highpass filter can be approximated by:
where f-3dB is the -3dB cutoff frequency of the filter,
RSPKR is the DC resistance of the speaker, and COUT is
the value of the output-coupling capacitor. As with the
input capacitor, choose COUT such that f-3dB is well
below the lowest frequency of interest. Setting f-3dB too
high affects the amplifier‘s low-frequency response.
Select capacitors with low ESR to minimize power loss-
es. Since the output-coupling capacitor has a large
amplitude AC current (resulting average output current
due to the LC filter) flowing through it at high output
powers, it is important to select an output-coupling
capacitor that has an appropriate ripple current rating.
To prevent damage to the output-coupling capacitor,
use the following equation to calculate the required
RMS ripple current rating for COUT:
where IRMS_RIPPLE is the minimum required RMS ripple
current rating for COUT and RSPKR is the DC resistance
of the speaker. The ripple current ratings of capacitors
are frequency dependent, so be sure to select a
capacitor based on its ripple current rating within the
audio frequency range.
Select output-coupling capacitors with DC voltage rat-
ings greater than VDD.
In single-supply operation with single-ended outputs, the
leakage current of COUT can affect the startup time of
the MAX9742. To minimize startup time delays due to
COUT, use capacitors with leakage current ratings less
than 1A for COUT. See the Startup Time Considerations
section for more information on optimizing the startup
time of the MAX9742.
Setting VMID
The voltage present at the MID input biases the internal
amplifiers and should be set to the average value of
VDD and VSS for maximum dynamic range. For dual-
supply operation, connect MID to ground. For single-
supply operation, set MID to 0.5 x VDD through an
external resistive divider. To minimize power dissipation
while providing enough input bias current for the MID
input, select divider-resistors with values greater than
or equal to 10k and less than or equal to 20k.
Connect a decoupling network between MID and the
SGND plane (see the
Supply Bypassing/Layout sec-
tion) to provide a sufficient low- and high-frequency AC
ground for the internal amplifiers. Figure 11 shows the
recommended decoupling networks for bypassing the
MID input.
I
V
2.83
R
RMS_RIPPLE
DD
SPKR
=
×
()
A
f
1
2R
C
3dB
SPKR
OUT
=
××
()
π
Hz
MAX9742
Single-/Dual-Supply, Stereo 16W,
Class D Amplifier with Differential Inputs
______________________________________________________________________________________
23
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX9742ETX+ | 功能描述:音频放大器 Stereo 16W Class D Amplifier 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 |
| MAX9742ETX+T | 功能描述:音频放大器 Stereo 16W Class D Amplifier 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 |
| MAX9742EVKIT+ | 功能描述:音频放大器 Evaluation Kit for the MAX9742 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 |
| MAX9744ETH+ | 功能描述:音频放大器 Stereo 20W Class D Amplifier 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 |
| MAX9744ETH+T | 功能描述:音频放大器 Stereo 20W Class D Amplifier 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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