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參數(shù)資料
| 型號： | MAX9712 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 500mW. Low EMI. Filterless. Class D Audio Amplifier |
| 中文描述： | 500mW、低EMI、無需濾波、D類音頻放大器 |
| 文件頁數(shù)： | 8/18頁 |
| 文件大?。?/td> | 537K |
| 代理商： | MAX9712 |
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Detailed Description
The MAX9712 filterless, class D audio power amplifier
features several improvements to switch-mode amplifier
technology. The MAX9712 offers class AB performance
with class D efficiency, while occupying minimal board
space. A unique filterless modulation scheme, synchro-
nizable switching frequency, and SSM mode create a
compact, flexible, low-noise, efficient audio power
amplifier. The differential input architecture reduces
common-mode noise pick-up, and can be used without
input-coupling capacitors. The device can also be con-
figured as a single-ended input amplifier.
Comparators monitor the MAX9712 inputs and com-
pare the complementary input voltages to the 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)
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 (the first comparator to trip) while the
other output pulse duration remains at t
ON(min)
. This
causes the net voltage across the speaker (V
OUT+
-
V
OUT-
) to change.
Operating Modes
Fixed-Frequency Modulation (FFM) Mode
The MAX9712 features two FFM modes. The FFM
modes are selected by setting SYNC = GND for a
1.1MHz switching frequency, and SYNC = FLOAT for a
1.45MHz switching frequency. In FFM mode, the fre-
quency spectrum of the class D output consists of the
fundamental switching frequency and its associated
harmonics (see the Wideband FFT graph in the
Typical
Operating Characteristics
). The MAX9712 allows the
switching frequency to be changed by +32%, should
the frequency of one or more of the harmonics fall in a
sensitive band. This can be done at any time and does
not affect audio reproduction.
Spread-Spectrum Modulation (SSM) Mode
The MAX9712 features a unique, patented spread-spec-
trum mode that flattens the wideband spectral compo-
nents, improving EMI emissions that may be radiated by
the speaker and cables by 5dB. Proprietary techniques
ensure that the cycle-to-cycle variation of the switching
period does not degrade audio reproduction or efficien-
cy (see the
Typical Operating Characteristics
). Select
SSM mode by setting SYNC = V
DD
. In SSM mode, the
switching frequency varies randomly by
±
120kHz
around the center frequency (1.22MHz). The modulation
scheme remains the same, but the period of the saw-
tooth 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
500mW, Low EMI, Filterless,
Class D Audio Amplifier
8
_______________________________________________________________________________________
Pin Description
PIN
BUMP
UCSP
C4
B4
A4
A3
B3
TDFN/μMAX
1
2
3
4
5
NAME
FUNCTION
V
DD
IN+
IN-
GND
SHDN
Analog Power Supply
Noninverting Audio Input
Inverting Audio Input
Analog Ground
Active-Low Shutdown Input. Connect to V
DD
for normal operation.
Frequency Select and External Clock Input.
SYNC = GND:
Fixed-frequency mode with f
S
= 1100kHz.
SYNC = Float:
Fixed-frequency mode with f
S
= 1450kHz.
SYNC = V
DD
:
Spread-spectrum mode with f
S
= 1220kHz
±
120kHz.
SYNC = Clocked:
Fixed-frequency mode with f
S
= external clock frequency.
Power Ground
Amplifier Output Positive Phase
Amplifier Output Negative Phase
H-Bridge Power Supply
6
C2
SYNC
7
8
9
10
B2
C1
A1
B1
PGND
OUT+
OUT-
PV
DD
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX9712EUB+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX9713ETJ | 功能描述:音頻放大器 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 |
| MAX9713ETJ+ | 功能描述:音頻放大器 6W Filterless 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 |
| MAX9713ETJ+T | 功能描述:音頻放大器 6W Filterless 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 |
| MAX9713ETJ-T | 功能描述:音頻放大器 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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