The AC-coupling capacitor (CIN) and input resistor (R<" />
參數(shù)資料
型號： MAX9729ETI+T
廠商： Maxim Integrated Products
文件頁數(shù)： 15/28頁
文件大?。?/td> 0K
描述： IC AMP AUDIO .052W STER 28TQFN
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，2-通道（立體聲）
在某負載時最大輸出功率 x 通道數(shù)量： 52mW x 2 @ 32 歐姆
電源電壓： 1.8 V ~ 3.6 V
特點： 帶低音增強模式，消除爆音，I²C，輸入多路復(fù)用器，短路和熱保護，關(guān)機，音量控制
安裝類型： 表面貼裝
供應(yīng)商設(shè)備封裝： 28-TQFN-EP（5x5）
封裝/外殼： 28-WFQFN 裸露焊盤
包裝： 帶卷 (TR)
MAX9729
Input-Coupling Capacitor
The AC-coupling capacitor (CIN) and input resistor (RIN)
form a highpass filter that removes any DC bias from an
input signal. See the
Functional Diagram/Typical
Operating Circuit. CIN prevents any DC components
from the input signal source from appearing at the
amplifier outputs. The -3dB point of the highpass filter,
assuming zero source impedance due to the input sig-
nal source, is given by:
Choose CIN such that f-3dB is well below the lowest fre-
quency of interest. Setting f-3dB too high affects the
amplifier’s low-frequency response. Use capacitors with
low-voltage coefficient dielectrics. Aluminum electrolytic,
tantalum, or film dielectric capacitors are good choices
for AC-coupling capacitors. Capacitors with high-voltage
coefficients, such as ceramics (non-C0G dielectrics),
can result in increased distortion at low zero frequen-
cies. If a ceramic capacitor is selected due to board
space or cost constraints, use the largest package pos-
sible to minimize voltage coefficient effects. In addition,
use X7R dielectrics as opposed to X5R, Y5V, or Z5U.
BassMax Gain-Setting Components
The bass boost, low-frequency response when
BassMax is enabled, is set by the ratio of R1 to R2 (see
Figure 2), by the following equation:
where AV_BOOST is the gain boost, in dB, at low fre-
quencies. AV_BOOST is added to the gain realized by
the maximum gain setting and the volume setting. The
total gain at low frequencies is equal to:
where AV_TOTAL_BM is the total voltage gain at low fre-
quencies in dB, AV_MAX is the maximum gain setting in
dB, and ATTEN is the volume attenuation in dB. To
maintain circuit stability, the ratio:
must not exceed 1/2. A ratio equaling 1/3 is recommend-
ed. The switch that shorts BM_ to SGND, when BassMax
is disabled, can have an on-resistance as high as 300Ω.
Choose a value for R1 that is greater than 40kΩ to
ensure that positive feedback is negligible when
BassMax is disabled. Table 10 contains a list of R2 val-
ues, with R1 = 47kΩ, and the corresponding low-fre-
quency gain boost values.
The low-frequency boost attained by the BassMax cir-
cuit is added to the gain realized by the maximum gain
setting and volume setting. Select the BassMax gain so
that the output signal will remain within the dynamic
range of the MAX9729. Output signal clipping will occur
at low frequencies if the BassMax gain boost is exces-
sively large. See the
Output Dynamic Range section.
Capacitor C4 forms a pole and a zero according to the
following equations:
fPOLE is the frequency at which the gain boost begins
to roll off. fZERO is the frequency at which the bass
boost gain no longer affects the transfer function. At
frequencies greater than or equal to fZERO, the gain set
by the maximum gain setting and the volume control
attenuation dominate. Table 11 contains a list of capac-
itor values and the corresponding poles and zeros for a
given DC gain. See Figure 9 for an example of a gain
profile using BassMax.
Layout and Grounding
Proper layout and grounding are essential for optimum
performance. Connect PGND and SGND together at a
single point (star ground point) on the PCB near the
MAX9729. Connect PVSS and SVSS together at C2.
Place C2 physically close to PVSS and SVSS and con-
nect it to PGND. Bypass PVDD to PGND with C3.
Connect C3 as close to PVDD as possible. Bypass VDD
to SGND with a 1F capacitor. Place the VDD bypass
f
RR
CR
R
Hz
f
RR
CR
R
Hz
POLE
ZERO
=
××
×
=
+
××
×
12
26
1
2
12
26
1
2
π
()
R
RR
2
12
+
A
ATTEN
A
dB
V TOTAL BM
V MAX
V BOOST
__
_
()
=
+
A
RR
dB
V BOOST
_
log
(
)
=×
+
20
12
f
RC
Hz
dB
IN
=
××
3
1
2
π
()
Stereo Headphone Amplifier with BassMax,
Volume Control, and Input Mux
22
______________________________________________________________________________________
R2 (k
Ω)AV_BOOST (dB)
39
20.6
33
15.1
27
11.3
22
8.8
15
5.7
10
3.7
Table 10. BassMax Gain Examples,
R1 = 47kΩ
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX9729EVCMAXQU+ 功能描述:音頻放大器 Evaluation Kit/Evaluation System for the MAX9729 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
MAX9729EVKIT+ 功能描述:音頻放大器 Evaluation Kit/Evaluation System for the MAX9729 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
MAX972C/D 功能描述:校驗器 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel
MAX972CPA 功能描述:校驗器 IC Dual Comparator RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel
MAX972CPA+ 功能描述:校驗器 IC Dual Comparator RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel
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