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參數(shù)資料
| 型號： | MAX9702B |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 1.8W, Filterless, Stereo, Class D Audio Power Amplifier and DirectDrive Stereo Headphone Amplifier |
| 中文描述： | 1.8W的，濾波，立體聲D類音頻功率放大器和DirectDrive立體聲耳機放大器 |
| 文件頁數(shù)： | 14/32頁 |
| 文件大?。?/td> | 1411K |
| 代理商： | MAX9702B |
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M
1.8W, Filterless, Stereo, Class D Audio Power
Amplifier and DirectDrive Stereo Headphone Amplifier
14
______________________________________________________________________________________
Detailed Description
The MAX9702 is a 1.8W, filterless, stereo Class D audio
power amplifier and DirectDrive stereo headphone
amplifier. The MAX9702 SSM amplifier features signifi-
cant improvements to switch-mode amplifier technolo-
gy. The MAX9702 offers Class AB performance with
Class D efficiency and minimal board space. The
device offers mix, mute, mono and stereo input modes,
eight selectable gains, and a low-power shutdown
mode—all programmable through an I
2
C interface.
The MAX9702 stereo headphone amplifier features
Maxim’s patented DirectDrive architecture, which elimi-
nates the large output-coupling capacitors required by
conventional single-supply headphone amplifiers. A
negative supply (V
SS
) is created internally by inverting
the positive supply (CPV
DD
). Powering the amplifiers
from CPV
DD
and CPV
SS
increases the dynamic range of
the amplifiers to almost twice that of other single-supply
amplifiers, increasing the total available output power.
The DirectDrive outputs of the MAX9702 are biased at
GND (see Figure 7). The benefit of this 0V bias is that
the amplifier outputs do not have a DC component,
eliminating the need for large DC-blocking capacitors.
Eliminating the DC-blocking capacitors on the output
saves board space, system cost, and improves fre-
quency response.
The MAX9702 features extensive click-and-pop sup-
pression circuitry on both speaker and headphone
amplifiers to eliminate audible clicks-and-pops on start-
up and shutdown.
The MAX9702 features an input multiplexer/mixer that
allows three different audio sources to be selected or
mixed. An I
2
C-compatible interface allows serial com-
munication between the MAX9702 and a microcon-
troller. The MAX9702 is available with two different I
2
C
addresses allowing two MAX9702s to share the same
bus (see Table 2). The internal command register con-
trols the shutdown status of the MAX9702, sets the
maximum gain of the amplifier, and controls the
mono/stereo/mixed/mute MUX inputs (see Table 3).
Class D Speaker Amplifier
Spread-spectrum modulation and synchronizable
switching frequency significantly reduce EMI emis-
sions. Comparators monitor the audio inputs and com-
pare the complementary input voltages to a sawtooth
waveform. The comparators trip when the input magni-
tude of the sawtooth exceeds their corresponding input
voltage. Both comparators reset at a fixed time after the
rising edge of the second comparator trip point, gener-
ating a minimum-width pulse (t
ON(MIN)
,100ns typ) at
the output of the second comparator (Figure 1). As the
input voltage increases or decreases, the duration of
the pulse at one output increases while the other output
pulse duration remains the same. This causes the net
voltage across the speaker (V
OUT+
- V
OUT-
) to change.
The minimum-width pulse helps the device to achieve
high levels of linearity.
Operating Modes
Fixed-Frequency (FFM) Mode
The MAX9702 features two fixed-frequency modes.
Connect SYNC to GND to select a 1.1MHz switching fre-
quency. Float SYNC to select a 1.34MHz switching fre-
quency. The frequency spectrum of the MAX9702
consists of the fundamental switching frequency and its
associated harmonics (see the Wideband FFT graph in
Typical Operating Characteristics
). Program the switch-
ing frequency such that the harmonics do not fall within
a sensitive frequency band (Table 1). Audio reproduc-
tion is not affected by changing the switching frequency.
Spread-Spectrum (SSM) Mode
The MAX9702 features a unique, patented 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 = V
DD
to enable SSM (Table
1). In SSM mode, the switching frequency varies ran-
domly by ±50kHz around the center frequency
(1.15MHz). The modulation scheme remains the same,
but the period of the sawtooth waveform changes from
cycle to cycle (Figure 2). 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 (Figure 3). A proprietary amplifier topology
ensures this does not corrupt the noise floor in the
audio bandwidth.
Table 1. Operating Modes
SYNC
GND
FLOAT
V
DD
MODE
FFM with f
OSC
= 1100kHz
FFM with f
OSC
= 1340kHz
SSM with f
OSC
= 1150kHz ±50kHz
FFM with f
OSC
= external clock
frequency
Clocked
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX9703 | Hex 2-Input OR Drivers 20-CDIP -55 to 125 |
| MAX9703-MAX9704 | 15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers |
| MAX9703ETJ | 15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers |
| MAX9704ETJ | 15W, Filterless, Spread-Spectrum Mono/Stereo Class D Amplifiers |
| MAX9711ETC | Synchronous 8-Bit Up/Down Counters 28-LCCC -55 to 125 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX9702BETI+ | 制造商:Maxim Integrated Products 功能描述:AUD AMP HDPH/SPKR 2CH STEREO 1.8W/0.045W CLS-AB/CLS-D 28TQFN - Rail/Tube |
| MAX9702BETI+T | 制造商:Maxim Integrated Products 功能描述:AUD AMP HDPH/SPKR 2CH STEREO 1.8W/0.045W CLS-AB/CLS-D 28TQFN - Tape and Reel |
| MAX9702BEUI+ | 制造商:Maxim Integrated Products 功能描述:AUD AMP HDPH/SPKR 2CH STEREO 1.8W/0.045W CLS-AB/CLS-D 28TSSO - Rail/Tube |
| MAX9702BEUI+T | 制造商:Maxim Integrated Products 功能描述:AUD AMP HDPH/SPKR 2CH STEREO 1.8W/0.045W CLS-AB/CLS-D 28TSSO - Tape and Reel |
| MAX9702ETI+ | 功能描述:音頻放大器 1.8W Filterless Class D Audio Amp 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 |
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