參數(shù)資料
型號(hào)： MAX9744ETH+T
廠商： Maxim Integrated Products
文件頁(yè)數(shù)： 6/28頁(yè)
文件大?。?/td> 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： 1
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： 標(biāo)準(zhǔn)包裝
其它名稱： MAX9744ETH+TDKR
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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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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
MAX974CPE+ 功能描述:校驗(yàn)器 IC Dual Comparator / Reference 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
MAX974CSE 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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