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参数资料
| 型号： | MAX9744ETH+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 6/28页 |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO PWR 22.5W D 44TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| 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： | 22.5W x 2 @ 4 欧姆 |
| 电源电压： | 4.5 V ~ 14 V |
| 特点： | 消除爆音，静音，短路和热保护，关机，音量控制 |
| 安装类型： | 表面贴装 |
| 供应商设备封装： | 44-TQFN-EP（7x7） |
| 封装/外壳： | 44-WFQFN 裸露焊盘 |
| 包装： | 标准包装 |
| 其它名称： | MAX9744ETH+TDKR |
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MAX9744
20W Stereo Class D Speaker Amplifier
with Volume Control
14
______________________________________________________________________________________
Spread-Spectrum Modulation Mode
The MAX9744 features a unique spread-spectrum
mode that flattens the wideband spectral components,
improving EMI emissions that may be radiated by the
speaker and cables. This mode is enabled by setting
SYNC = VDD (Table 1). In spread-spectrum mode, the
switching frequency varies randomly by ±7.5kHz
around the center frequency (300kHz). The modulation
scheme remains the same, but the period of the trian-
gle waveform changes from cycle to cycle. Instead of a
large amount of spectral energy present at multiples of
the switching frequency, the energy is now spread over
a bandwidth that increases with frequency. Above a
few megahertz, the wideband spectrum looks like white
noise for EMI purposes. A proprietary amplifier topolo-
gy ensures this does not corrupt the noise floor in the
audio bandwidth.
External Clock Mode
The SYNC input allows the MAX9744 to be synchro-
nized to an external clock or another Maxim Class D
amplifier, creating a fully synchronous system. This
minimizes clock intermodulation and allocates spectral
components of the switching harmonics to insensitive
frequency bands. Applying a clock signal between
1MHz and 1.6MHz to SYNC synchronizes the
MAX9744. The MAX9744 Class D amplifier operates at
1/4 of the SYNC frequency. For example, if SYNC is
1.6MHz, the Class D amplifier operates at 400kHz.
The external SYNC signal can be any CMOS clock
source with a 40% to 60% duty cycle. Spread-spectrum
clocks work well to reduce EMI; therefore, the
SYNCOUT signal from another MAX9744 in spread-
spectrum mode is an excellent SYNC input.
SYNCOUT allows several Maxim amplifiers to be cas-
caded (Figure 1). The synchronized output minimizes
interference due to clock intermodulation caused by the
switching spread between single devices. Using
SYNCOUT and SYNC does not affect the audio perfor-
mance of the MAX9744.
Filterless Modulation/PWM Modulation
The MAX9744 features two output modulation schemes:
filterless modulation or classic PWM. The MAX9744 out-
put modulation schemes are selectable through
SCLK/PWM when the device is in analog mode (ADDR1
and ADDR2 = GND, Table 2) or through the I2C inter-
face (Table 8). Maxim’s unique, filterless modulation
scheme eliminates the LC filter required by traditional
Class D amplifiers, reducing component count and con-
serving board space and system cost. Although the
MAX9744 meets FCC and other EMI limits with a low-
cost ferrite bead filter, many applications still may want
to use a full LC-filtered output. If using a full LC filter,
audio performance is best with the MAX9744 configured
for classic PWM output.
Switching between schemes, the output is not click-and-
pop protected. To have click-and-pop protection when
switching between output schemes, the device must
enter shutdown mode and be configured to the new out-
put scheme before the startup sequence is finished.
SYNCOUT
OUTL+
OUTL-
OUT+
OUT-
SYNC
MAX9744
MAX9709
OUTR+
OUTR-
SYNC
SYNC INPUT
Figure 1. Cascading Two Amplifiers’ External Clock Mode
SYNC
MODE
fSYNC (kHz) fSW (kHz)
GND
Fixed-frequency
modulation
1200
300
Unconnected
Fixed-frequency
modulation
1440
360
VDD
Spread-spectrum
modulation
1200 ±30
300 ±7.5
Clocked
EXT
1000 to
1600
250 to
400
Table 1. Operating Modes
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX9744EVCMAXQU+ | 功能描述:音频放大器 Evaluation Kit/Evaluation System for the MAX9744 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 |
| MAX9744EVKIT+ | 功能描述:音频放大器 Evaluation Kit/Evaluation System for the MAX9744 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 |
| MAX974CPE | 功能描述:校验器 IC RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
| MAX974CPE+ | 功能描述:校验器 IC Dual Comparator / Reference RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
| MAX974CSE | 功能描述:校验器 IC RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
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