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| 型号： | MAX9729ETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 4/28页 |
| 文件大小： | 0K |
| 描述： | IC AMP AUDIO .052W STER 28TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | DirectDrive® |
| 类型： | AB 类 |
| 输出类型： | 耳机，2-通道（立体声） |
| 在某负载时最大输出功率 x 通道数量： | 52mW x 2 @ 32 欧姆 |
| 电源电压： | 1.8 V ~ 3.6 V |
| 特点： | 带低音增强模式，消除爆音，I²C，输入多路复用器，短路和热保护，关机，音量控制 |
| 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) |
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MAX9729
contents of the command register are not affected
when in shutdown. This allows the master device to
write to the MAX9729 while in shutdown.
When a shutdown is activated, either hardware (
SHDN
pin) or software (I2C register), the volume is smoothly
reduced, according to a constant slope ramp. Similarly,
when a shutdown is deactivated, either hardware or
software, the volume is smoothly increased, according
to a constant slope ramp, until the volume programmed
in the register file is reached.
BassMax (Bass Boost)
Typical headphones do not have a flat-frequency
response. The small physical size of the diaphragm
does not allow the headphone speaker to efficiently
reproduce low frequencies. This physical limitation
results in attenuated bass response. The MAX9729
includes a bass boost feature that compensates for the
headphone’s poor bass response by increasing the
amplifier gain at low frequencies.
The DirectDrive output of the MAX9729 has more head-
room than typical single-supply headphone amplifiers.
This additional headroom allows boosting the bass fre-
quencies without the output signal clipping.
Program the BassMax gain and cutoff frequency with
external components connected between OUT_ and
BM_ (see the
BassMax Gain-Setting Components sec-
tion and the
Functional Diagram/Typical Operating
Circuit). Use the I2C-compatible interface to program the
command register to enable/disable the BassMax circuit.
BM_ is connected to the noninverting input of the out-
put amplifier when BassMax is enabled. BM_ is pulled
to SGND when BassMax is disabled. The typical appli-
cation of the BassMax circuit involves feeding a low-
pass-filtered version of the output signal back to the
amplifier. This is realized using positive feedback from
OUT_ to BM_. Figure 2 shows the connections needed
to implement BassMax.
Maximum Gain Control
The MAX9729 features eight different programmable
maximum gain settings ranging from +3.5dB to +26dB
(see Table 8). Bits [2:0] in command register 0x01 con-
trol the maximum gain setting (AV_MAX).
Volume Control
The MAX9729 includes a 32-level volume control that
adjusts the total voltage gain of the headphone amplifi-
er according to the values of bits [4:0] in the 0x00 com-
mand register. With BassMax disabled, the total
voltage gain of the MAX9729 is equal to:
where AV_TOTAL is the total voltage gain in dB, AV_MAX
is the maximum gain setting in dB, and ATTEN is the
volume attenuation in dB.
Tables 5a, 5b, 5c show all the possible volume attenua-
tion settings and the resulting AV_TOTAL with BassMax
disabled. Figure 8 shows the volume control transfer
function. Mute attenuation is typically better than 100dB
when driving a 32Ω load. To perform smooth-sounding
volume changes, step through all intermediate volume
settings at a rate of approximately 2ms per step when a
volume change occurs.
Automatic Volume Ramping During Mode
Transitions and Input Source Selection
The MAX9729 implements an automatic volume ramp-
up/ramp-down function when exiting/entering shutdown
and when selecting different input signal paths with the
internal 3:1 multiplexer. The automatic volume ramp-
up/ramp-down function steps through each intermedi-
ate volume setting at a rate of 1.5ms per step allowing
for smooth sounding volume transitions. When
exiting/entering shutdown, the volume ramp-up/ramp-
down function is implemented regardless of whether
the shutdown command is initiated by an I2C command
or the
SHDN input. When exiting shutdown, the volume
is ramped up to the value stored in register 0x00 (see
Table 2). When selecting a new input signal path with
the multiplexer, the MAX9729 first ramps down the vol-
ume, selects the new input source, and then ramps the
volume back up to the value stored in register 0x00.
This prevents any audible clicks and pops due to
abrupt changes in signal amplitude when selecting a
different input signal source.
A
ATTEN dB
V TOTAL
V MAX
__
()
=
Stereo Headphone Amplifier with BassMax,
Volume Control, and Input Mux
12
______________________________________________________________________________________
C6
R2
R1
R
OUT_
BM_
FROM
VOLUME
ATTENUATOR
STAGE
MAX9729
BassMax
ENABLE
TO HEADPHONE
SPEAKER
Figure 2. BassMax External Connections
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX9729EVCMAXQU+ | 功能描述:音频放大器 Evaluation Kit/Evaluation System for the MAX9729 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 |
| MAX9729EVKIT+ | 功能描述:音频放大器 Evaluation Kit/Evaluation System for the MAX9729 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 |
| MAX972C/D | 功能描述:校验器 IC RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
| MAX972CPA | 功能描述:校验器 IC Dual Comparator RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
| MAX972CPA+ | 功能描述:校验器 IC Dual Comparator RoHS:否 制造商:STMicroelectronics 产品: 比较器类型: 通道数量: 输出类型:Push-Pull 电源电压-最大:5.5 V 电源电压-最小:1.1 V 补偿电压（最大值）:6 mV 电源电流（最大值）:1350 nA 响应时间: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SC-70-5 封装:Reel |
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