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参数资料
| 型号： | MAX9744ETH+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 7/28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
______________________________________________________________________________________
15
Efficiency
The high efficiency of a Class D amplifier is due to the
switching operation of the output stage transistors. In a
Class D amplifier, the output transistors act as current-
steering switches and consume negligible additional
power. Any power loss associated with the Class D out-
put stage is mostly due to the I2R loss of the MOSFET
on-resistance, and quiescent current overhead.
The theoretical best efficiency of a linear amplifier is
78% at peak output power. Under normal operating lev-
els (typical music reproduction levels), the efficiency
falls below 30%, whereas the MAX9744 exhibits > 80%
efficiency under the same conditions (Figure 2).
Current Limit
When the output current exceeds the current limit, 5.5A
(typ), the MAX9744 disables the outputs and initiates a
220s startup sequence. The shutdown and startup
sequence is repeated until the output fault is removed.
Since the retry repetition is slow, the average supply
current is low. Most applications do not enter current-
limit mode unless the output is short circuited or incor-
rectly connected.
Thermal Shutdown
When the die temperature exceeds the thermal-shut-
down threshold, +165°C (typ), the MAX9744 outputs
are disabled. Normal operation resumes when the die
temperature decreases by a factor equal to the
thermal-shutdown threshold minus the thermal-shut-
down hysteresis, (typically below +150°C). The effect of
thermal shutdown is an output signal turning off for
approximately 3s in most applications, depending on
the thermal time constant of the audio system. Most
applications should never enter thermal shutdown.
Some of the possible causes of thermal shutdown are
too low of a load impedance, bad thermal contact
between the MAX9744’s exposed pad and PCB, high
ambient temperature, poor PCB layout and assembly,
or excessive output overdrive.
Shutdown
The MAX9744 features a shutdown mode that reduces
power consumption and extends battery life. Driving
SHDN low places the device in low-power shutdown
mode. Connect SHDN to digital high for normal opera-
tion. In shutdown mode, the outputs are high imped-
ance, SYNCOUT is pulled high, BIAS voltage decays to
zero, and the common-mode input voltage decays to
zero. The I2C register does not retain its contents dur-
ing shutdown (MAX9744).
Mute Function
The MAX9744 features a clickless-and-popless mute
mode. When the device is muted, the outputs do not
stop switching; only the volume level is muted to the
speaker. Mute only affects the output stage and does
not shut down the device. To mute the MAX9744, drive
MUTE to logic-high. MUTE should be held high during
system power-up and power-down to ensure that pops
caused by circuits before the MAX9744 are eliminated.
To reduce clicks and pops, the device enters or exits
mute at zero crossing.
EFFICIENCY
vs. OUTPUT POWER
MAX9744/45
fig02
OUTPUT POWER (W)
EFFICIENCY
(%)
8
6
4
2
10
20
30
40
50
60
70
80
90
100
0
010
MAX9744
CLASS AB
PVDD = 12V
fIN = 1kHz
RL = 4
Ω
Figure 2. MAX9744 Efficiency vs. Class AB Efficiency
ADDR2
ADDR1
SDA/VOL
SCLK/PWM
FUNCTION
0
Analog volume control
0
Filterless modulation
0
Analog volume control
1
Classic PWM (50% duty cycle)
Table 2. Modulation Scheme Selection
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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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