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| 型号： | MAX9770ETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 8/22页 |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO 1.2W MONO D 28TQFN |
| 标准包装： | 2,500 |
| 类型： | D 类 |
| 输出类型： | 1-通道（单声道），带立体声耳机 |
| 在某负载时最大输出功率 x 通道数量： | 1.2W x 1 @ 8 欧姆; 80mW x 2 @ 16 欧姆 |
| 电源电压： | 2.5 V ~ 5.5 V |
| 特点： | 消除爆音，输入多路复用器，静音，短路和热保护，关机 |
| 安装类型： | 表面贴装 |
| 供应商设备封装： | 28-TQFN-EP（5x5） |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
MAX9770
the device changes when a headphone is inserted or
removed. For example, the block diagram shows HPS
connected to GAIN2, while GAIN1 is connected to VDD.
In this configuration, the gain in speaker mode is 9dB,
while the gain in headphone mode is 1dB. The gain
settings with the HPS connection are shown in Table 4.
Shutdown
The MAX9770 features a 0.1A, low-power shutdown
mode that reduces quiescent current consumption and
extends battery life. Drive SHDN low to disable the
drive amplifiers, bias circuitry, and charge pump. Bias
is driven to GND and the headphone amplifier output
impedance is 10k
Ω in shutdown. Connect SHDN to
VDD for normal operation.
Click-and-Pop Suppression
Speaker Amplifier
The MAX9770 speaker amplifier features comprehen-
sive click-and-pop suppression that eliminates audible
transients on startup and shutdown. While in shutdown,
the H-bridge is in a high-impedance state. During start-
up or power-up, the input amplifiers are muted and an
internal loop sets the modulator bias voltages to the cor-
rect levels, preventing clicks and pops when the H-
bridge is subsequently enabled. A soft-start function
unmutes the input amplifiers 30ms after startup.
Headphone Amplifier
In conventional single-supply headphone drivers, the
output-coupling capacitor is a major contributor of
audible clicks and pops. Upon startup, the driver
charges the coupling capacitor to its bias voltage, typi-
cally half the supply. Likewise, during shutdown, the
capacitor is discharged to GND. This results in a DC
shift across the capacitor, which in turn, appears as an
audible transient at the speaker. Since the MAX9770
headphone amplifier does not require output-coupling
capacitors, this does not arise.
Additionally, the MAX9770 features extensive click-and-
pop suppression that eliminates any audible transient
sources internal to the device. The Exiting Shutdown
(Headphone Mode) and Entering Shutdown (Headphone
Mode) graphs in the
Typical Operating Characteristics
shows that there are minimal spectral components in the
audible range at the output upon startup or shutdown.
In most applications, the output of the preamplifier dri-
ving the MAX9770 has a DC bias of typically half the
supply. During startup, the input-coupling capacitor is
charged to the preamplifier’s DC bias voltage through
the RF of the MAX9770, resulting in a DC shift across the
capacitor and an audible click-and-pop. An internal
delay of 50ms eliminates the click-and-pop caused by
the input filter.
Applications Information
Filterless Operation
Traditional Class D amplifiers require an output filter to
recover the audio signal from the amplifier’s output. The
filters add cost, increase the solution size of the amplifi-
er, and can decrease efficiency. The traditional PWM
scheme uses large differential output swings (2 x VDD
peak-to-peak) at idle and causes large ripple currents.
Any parasitic resistance in the filter components results
in a loss of power, lowering efficiency.
The MAX9770 does not require an output filter. The
device relies on the inherent inductance of the speaker
coil and the natural filtering of both the speaker and the
human ear to recover the audio component of the
square-wave output. Eliminating the output filter results in
a smaller, less costly, and more efficient solution.
Because the frequency of the MAX9770 output is well
beyond the bandwidth of most speakers, voice coil
movement due to the square-wave frequency is minimal.
1.2W, Low-EMI, Filterless, Mono Class D Amplifier
with Stereo DirectDrive Headphone Amplifiers
16
______________________________________________________________________________________
Table 3. Gain Selection
GAIN1
GAIN2
MAX9770
SPEAKER GAIN
(dB)
HEADPHONE
GAIN
(dB)
00
6
7
01
3
4
10
9
-2
11
0
1
Table 4. Gain Settings with HPS
Connection
GAIN1 GAIN2
MAX9770 SPEAKER
MODE GAIN
(HPS = 0)
(dB)
HEADPHONE MODE
GAIN
(HPS = 1)
(dB)
HPS
0
6
-2
HPS
1
3
1
0
HPS
6
4
1
HPS
9
1
HPS
6
1
00
6
7
01
3
4
10
9
-2
11
0
1
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| MAX9770EUI | 制造商:Rochester Electronics LLC 功能描述: |
| MAX9770EUI+ | 功能描述:音频放大器 1.2W Low-EMI Class D Amplifier RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| MAX9770EUI+T | 功能描述:音频放大器 1.2W Low-EMI Class D Amplifier RoHS:否 制造商:STMicroelectronics 产品:General Purpose Audio Amplifiers 输出类型:Digital 输出功率: THD + 噪声: 工作电源电压:3.3 V 电源电流: 最大功率耗散: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:TQFP-64 封装:Reel |
| MAX9770EVKIT | 功能描述:音频 IC 开发工具 Programmers, Development Systems RoHS:否 制造商:Texas Instruments 产品:Evaluation Kits 类型:Audio Amplifiers 工具用于评估:TAS5614L 工作电源电压:12 V to 38 V |
| MAX9772EBA | 制造商:Maxim Integrated Products 功能描述:1.2WLOW-EMIFILTERLESSMONO CLASS - Rail/Tube |
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