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| 型号： | MAX9741ETN+D |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 3/16页 |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO PWR 12W STER 56TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 37 |
| 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： | 12W x 2 @ 8 欧姆 |
| 电源电压： | 10 V ~ 25 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： | 56-TQFN-EP（8x8） |
| 封装/外壳： | 56-WFQFN 裸露焊盘 |
| 包装： | 管件 |
MAX9741
12W+12W, Low-EMI, Spread-Spectrum,
Stereo, Class D Amplifier
______________________________________________________________________________________
11
Single-Ended Input
The MAX9741 can be configured as single-ended input
amplifiers by capacitively coupling either input to GND
and driving the other input (Figure 4).
Component Selection
Input Filter
An input capacitor, CIN, in conjunction with the input
impedance of the MAX9741, forms a highpass filter that
removes the DC bias from an incoming signal. The AC-
coupling capacitor allows the amplifier to bias the sig-
nal to an optimum DC level. Assuming zero-source
impedance, the -3dB point of the highpass filter is
given by:
Choose CIN so f-3dB is well below the lowest frequency
of interest. Setting f-3dB too high affects the low-fre-
quency response of the amplifier. Use capacitors with
dielectrics that have low-voltage coefficients, such as
tantalum or aluminum electrolytic. Capacitors with high-
voltage coefficients, such as ceramics, may result in
increased distortion at low frequencies.
Charge-Pump Capacitor Selection
Use capacitors with an ESR less than 100m
for opti-
mum performance. Low-ESR ceramic capacitors mini-
mize the output resistance of the charge pump. For
best performance over the extended temperature
range, select capacitors with an X7R dielectric.
Flying Capacitor (C1)
The value of the flying capacitor (C1) affects the load
regulation and output resistance of the charge pump. A
C1 value that is too small degrades the device’s ability
to provide sufficient current drive. Increasing the value
of C1 improves load regulation and reduces the
charge-pump output resistance to an extent. Above
1F, the on-resistance of the switches and the ESR of
C1 and C2 dominate.
Hold Capacitor (C2)
The output capacitor value and ESR directly affect the rip-
ple at CHOLD. Increasing C2 reduces output ripple.
Likewise, decreasing the ESR of C2 reduces both ripple
and output resistance. Lower capacitance values can be
used in systems with low maximum output power levels.
Sharing Input Sources
In certain systems, a single audio source can be shared
by multiple devices (speaker and headphone amplifiers).
When sharing inputs, it is common to mute the unused
device, rather than completely shutting it down, prevent-
ing the unused device inputs from distorting the input
signal. Mute the MAX9741 by driving SS low through an
open-drain output or MOSFET. Driving SS low turns off
the Class D output stage, but does not affect the input
bias levels of the MAX9741. Be aware that during normal
operation, the voltage at SS can be up to 7V, depending
on the MAX9741 supply.
Supply Bypassing/Layout
Proper power-supply bypassing ensures low-distortion
operation. For optimum performance, bypass VDD to
PGND with a 0.1F or greater capacitor as close to each
VDD pin as possible. In some applications, a 0.1F
capacitor in parallel with a larger value, low-ESR ceramic
or aluminum electrolytic capacitor provides good results.
A low-impedance, high-current power-supply connection
to VDD is assumed. Additional bulk capacitance should
be added as required depending on the application and
power-supply characteristics. AGND and PGND should
be star connected to system ground. Refer to the
MAX9741 Evaluation Kit for layout guidance.
Class D Amplifier Thermal Considerations
Class D amplifiers provide much better efficiency and
thermal performance than a comparable Class AB
amplifier. However, the system’s thermal performance
must be considered with realistic expectations and
consideration of many parameters. This application
note examines Class D amplifiers using general exam-
ples to illustrate good design practices.
Continuous Sine Wave vs. Music
When a Class D amplifier is evaluated in the lab, often
a continuous sine wave is used as the signal source.
While this is convenient for measurement purposes, it
represents a worst-case scenario for thermal loading
on the amplifier. It is not uncommon for a Class D
amplifier to enter thermal shutdown if driven near maxi-
mum output power with a continuous sine wave.
f
RC
-3dB
IN
1
2
=
π
MAX9741
IN+
IN-
0.47
F
0.47
F
SINGLE-ENDED
AUDIO INPUT
Figure 4. Single-Ended Input
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX9741EVKIT | 制造商:Maxim Integrated Products 功能描述:12W+12W FILTERLESS - Rail/Tube 制造商:Maxim Integrated Products 功能描述:12W+12W FILTERLESS SPREAD-SPECTRU - Rail/Tube |
| 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 |
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