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參數(shù)資料
| 型號(hào)： | MAX9722BETE+T |
| 廠商： | Maxim Integrated Products |
| 文件頁(yè)數(shù)： | 6/21頁(yè) |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO .13W STER AB 16TQFN |
| 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： | 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： | 130mW x 2 @ 32 歐姆 |
| 電源電壓： | 2.4 V ~ 5.5 V |
| 特點(diǎn)： | 消除爆音，差分輸入，短路和熱保護(hù)，關(guān)閉 |
| 安裝類型： | 表面貼裝 |
| 供應(yīng)商設(shè)備封裝： | 16-TQFN-EP（3x3） |
| 封裝/外殼： | 16-WFQFN 裸露焊盤 |
| 包裝： | 帶卷 (TR) |
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MAX9722A/MAX9722B
such as the headphone socket used as a line output to
a home hi-fi system. In the upper diagram, any differ-
ence between the two GND references (represented by
VNOISE) causes current to flow through the screen of
cable between the two devices. This can cause noise
pickup at the receiver due to the potential divider
action of the audio screen cable impedance and the
GND wiring of the amplifier.
Introducing impedance between the jack socket and
GND of the notebook helps (as shown in the lower dia-
gram). This has the following effect:
Current flow (from GND potential differences) in the
cable screen is reduced, which is a safety issue.
It allows the MAX9722A/MAX9722B differential sensing
to reduce the GND noise seen by the receiver (amplifier).
The other side effect is that the differential headphone
jack sensing corrects the headphone crosstalk (from
introducing the resistance on the jack GND return).
Only one channel is depicted in Figure 9.
Figure 9 has some example numbers for resistance,
but the audio designer has control over only one series
resistance applied to the headphone jack return. Note
that this resistance can be bypassed for ESD purposes
at frequencies much higher than audio if required. The
upper limit for this added resistance is the amount of
output swing the headphone amplifier tolerates when
driving low-impedance loads. Any headphone return
current appears as a voltage across this resistor.
Piezoelectric Speaker Amplifier
Low-profile piezoelectric speakers can provide quality
sound for portable electronics. However, piezoelectric
speakers typically require large voltage swings
(>8VP-P) across the speaker element to produce usable
sound pressure levels. Power sources in portable
devices are usually low voltage in nature. Operating
from batteries, conventional amplifiers cannot provide
sufficient voltage swing to drive a piezoelectric speak-
er. However, the MAX9722’s DirectDrive architecture
can be configured to drive a piezoelectric speaker with
up to 12VP-P while operating from a single 5V supply.
The stereo MAX9722 features an inverting charge
pump that takes the positive +5V supply and creates a
negative -5V supply. Each output of the MAX9722 can
swing 6VP-P. This may be sufficient to drive a piezo-
electric speaker. If a higher output voltage is desired,
configuring the MAX9722A as a bridge-tied load (BTL)
amplifier (Figure 10) doubles the maximum output
swing as seen by the load to 12VP-P. In a BTL configu-
ration, the right channel of the MAX9722 serves as the
master amplifier, setting the gain of the device, driving
one side of the speaker, and providing signal to the left
channel. The left channel is configured as a unity-gain
follower, inverting the output of the right channel and
driving the other leg of the speaker. Use precision
resistors to set the gain of the left channel to ensure low
distortion and good matching.
The MAX9722 was tested with a Panasonic WM-R57A
piezoelectric speaker, and the resulting THD+N curves
are shown (Figures 11 and 12). Note in both graphs, as
frequency increases, the THD+N increases. This is due
5V, Differential Input, DirectDrive, 130mW
Stereo Headphone Amplifiers with Shutdown
14
______________________________________________________________________________________
MAX9722A
INR
OUTR
INL
OUTL
AUDIO
INPUT
1
μF
10k
Ω
10k
Ω
10k
Ω
10k
Ω
Figure 10. MAX9722 BTL Configuration
TOTAL HARMONIC DISTORTION PLUS
NOISE vs. OUTPUT VOLTAGE
MAX9722
fig11
OUTPUT POWER (mW)
THD+N
(%)
12
10
8
6
4
2
0.0010
0.0100
0.1000
1
10
100
0.0001
014
VDD = 5V
AV = -1V/V
OUTPUTS DRIVING
PIEZOELECTRIC SPEAKER
f = 100Hz
f = 20Hz
f = 1kHz
Figure 11. MAX9722 THD+N vs. Output Voltage
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX9722BEUE | 制造商:Maxim Integrated Products 功能描述:5V, DIFFERENTIAL INPUT, DIRECTDRIVE, 130MW ST - Bulk |
| MAX9722BEUE+ | 功能描述:音頻放大器 DirectDrive 130mW 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 |
| MAX9722BEUE+T | 功能描述:音頻放大器 DirectDrive 130mW 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 |
| MAX97236EVKIT# | 功能描述:放大器 IC 開發(fā)工具 MAX97236 Eval Kit RoHS:否 制造商:International Rectifier 產(chǎn)品:Demonstration Boards 類型:Power Amplifiers 工具用于評(píng)估:IR4302 工作電源電壓:13 V to 23 V |
| MAX97236EVKIT+ | 功能描述:放大器 IC 開發(fā)工具 MAX97236 Eval Kit RoHS:否 制造商:International Rectifier 產(chǎn)品:Demonstration Boards 類型:Power Amplifiers 工具用于評(píng)估:IR4302 工作電源電壓:13 V to 23 V |
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