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參數(shù)資料
| 型號(hào)： | MAX9744ETH+ |
| 廠商： | Maxim Integrated Products |
| 文件頁(yè)數(shù)： | 7/28頁(yè) |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO PWR 22.5W D 44TQFN |
| 產(chǎn)品培訓(xùn)模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標(biāo)準(zhǔn)包裝： | 43 |
| 類型： | D 類 |
| 輸出類型： | 2 通道（立體聲） |
| 在某負(fù)載時(shí)最大輸出功率 x 通道數(shù)量： | 22.5W x 2 @ 4 歐姆 |
| 電源電壓： | 4.5 V ~ 14 V |
| 特點(diǎn)： | 消除爆音，靜音，短路和熱保護(hù)，關(guān)機(jī)，音量控制 |
| 安裝類型： | 表面貼裝 |
| 供應(yīng)商設(shè)備封裝： | 44-TQFN-EP（7x7） |
| 封裝/外殼： | 44-WFQFN 裸露焊盤 |
| 包裝： | 管件 |
| 產(chǎn)品目錄頁(yè)面： | 1392 (CN2011-ZH PDF) |
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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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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX9744ETH+ | 功能描述:音頻放大器 Stereo 20W Class D Amplifier RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX9744ETH+T | 功能描述:音頻放大器 Stereo 20W Class D Amplifier RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX9744EVCMAXQU+ | 功能描述:音頻放大器 Evaluation Kit/Evaluation System for the MAX9744 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX9744EVKIT+ | 功能描述:音頻放大器 Evaluation Kit/Evaluation System for the MAX9744 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:General Purpose Audio Amplifiers 輸出類型:Digital 輸出功率: THD + 噪聲: 工作電源電壓:3.3 V 電源電流: 最大功率耗散: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TQFP-64 封裝:Reel |
| MAX974CPE | 功能描述:校驗(yàn)器 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補(bǔ)償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時(shí)間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel |
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