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參數(shù)資料
| 型號(hào)： | MAX9724AETC+ |
| 廠商： | Maxim Integrated Products |
| 文件頁數(shù)： | 19/19頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC AMP AUDIO .045W STER 12TQFN |
| 產(chǎn)品培訓(xùn)模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標(biāo)準(zhǔn)包裝： | 100 |
| 系列： | DirectDrive® |
| 類型： | AB 類 |
| 輸出類型： | 耳機(jī)，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： | 63mW x 2 @ 32 歐姆 |
| 電源電壓： | 2.7 V ~ 5.5 V |
| 特點(diǎn)： | 消除爆音，短路保護(hù)和熱保護(hù)，關(guān)閉 |
| 安裝類型： | 表面貼裝 |
| 供應(yīng)商設(shè)備封裝： | 12-TQFN EP（3x3） |
| 封裝/外殼： | 12-WQFN 裸露焊盤 |
| 包裝： | 管件 |
| 產(chǎn)品目錄頁面： | 1392 (CN2011-ZH PDF) |
| 配用： | MAX9724AEVKIT+-ND - EVALUATION KIT FOR MAX9724A/B MAX9724DEVKIT+-ND - KIT EVAL FOR MAX9724D |
MAX9724A/MAX9724B
Detailed Description
The MAX9724A/MAX9724B stereo headphone ampli-
fiers feature Maxim’s DirectDrive architecture, eliminat-
ing the large output-coupling capacitors required by
conventional single-supply headphone amplifiers. The
device consists of two 60mW Class AB headphone
amplifiers, undervoltage lockout (UVLO)/shutdown con-
trol, charge pump, and comprehensive click-and-pop
suppression
circuitry
(see
the
Functional
Diagram/Typical Operating Circuits). The charge pump
inverts the positive supply (VDD), creating a negative
supply (PVSS). The headphone amplifiers operate from
these bipolar supplies with their outputs biased about
PGND (Figure 1). The benefit of this PGND bias is that
the amplifier outputs do not have a DC component. The
large DC-blocking capacitors required with convention-
al headphone amplifiers are unnecessary, conserving
board space, reducing system cost, and improving fre-
quency response. The MAX9724A/MAX9724B feature
an undervoltage lockout that prevents operation from
an insufficient power supply and click-and-pop sup-
pression that eliminates audible transients on startup
and shutdown. The MAX9724A/MAX9724B also feature
thermal-overload and short-circuit protection.
DirectDrive
Conventional single-supply headphone amplifiers have
their outputs biased about a nominal DC voltage (typi-
cally half the supply) for maximum dynamic range.
Large-coupling capacitors are needed to block this DC
bias from the headphone. Without these capacitors, a
significant amount of DC current flows to the head-
phone, resulting in unnecessary power dissipation and
possible damage to both headphone and headphone
amplifier.
Maxim’s DirectDrive architecture uses a charge pump
to create an internal negative supply voltage, allowing
the MAX9724A/MAX9724B outputs to be biased about
GND. With no DC component, there is no need for the
large DC-blocking capacitors. The MAX9724A/
MAX9724B charge pumps require two small ceramic
capacitors, conserving board space, reducing cost,
and improving the frequency response of the head-
phone amplifier. See the Output Power vs. Load
Resistance and Charge-Pump Capacitor Size graph in
the
Typical Operating Characteristics for details of the
possible capacitor sizes. There is a low DC voltage on
the amplifier outputs due to amplifier offset. However,
the offsets of the MAX9724A/MAX9724B are typically
1.5mV, which, when combined with a 32Ω load, results
in less than 47A of DC current flow to the head-
phones.
Charge Pump
The MAX9724A/MAX9724B feature a low-noise charge
pump. The 270kHz switching frequency is well beyond
the audio range and does not interfere with audio sig-
nals. The switch drivers feature a controlled switching
speed that minimizes noise generated by turn-on and
turn-off transients. The di/dt noise caused by the para-
sitic bond wire and trace inductance is minimized by
limiting the switching speed of the charge pump.
Although not typically required, additional high-fre-
quency noise attenuation can be achieved by increas-
ing the value of C2 (see the
Functional Diagram/Typical
Operating Circuits).
RF Susceptibility
Modern audio systems are often subject to RF radiation
from sources like wireless networks and cellular phone
networks. Although the RF radiation is out of the audio
band, many signals, in particular GSM signals, contain
bursts or modulation at audible frequencies. Most ana-
log amplifiers demodulate the low-frequency envelope,
adding noise to the audio signal. The architecture of
60mW, DirectDrive, Stereo Headphone Amplifier
with Low RF Susceptibility and Shutdown
_______________________________________________________________________________________
9
VDD
-VDD
GND
VOUT
CONVENTIONAL DRIVER-BIASING SCHEME
DirectDrive BIASING SCHEME
VDD/2
VDD
GND
VOUT
2VDD
Figure 1. Conventional Driver Output Waveform vs.
MAX9724A/MAX9724B Output Waveform
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX9724AETC+ | 功能描述:音頻放大器 60mW DirectDrive Headphone 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 |
| MAX9724AETC+T | 功能描述:音頻放大器 60mW DirectDrive Headphone 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 |
| MAX9724AETC-T | 制造商:Maxim Integrated Products 功能描述:- Tape and Reel |
| MAX9724AEUD | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
| MAX9724AEUD+ | 功能描述:IC AMP AUDIO .045W STER 14TSSOP RoHS:是 類別:集成電路 (IC) >> 線性 - 音頻放大器 系列:DirectDrive® 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,500 系列:DirectDrive® 類型:H 類 輸出類型:耳機(jī)，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:35mW x 2 @ 16 歐姆 電源電壓:1.62 V ~ 1.98 V 特點(diǎn):I²C，麥克風(fēng)，靜音，短路保護(hù)，音量控制 安裝類型:表面貼裝 供應(yīng)商設(shè)備封裝:25-WLP（2.09x2.09） 封裝/外殼:25-WFBGA，WLCSP 包裝:帶卷 (TR) |
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