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| 型號： | MAX4411EVKIT |
| 廠商： | Maxim Integrated Products |
| 文件頁數(shù)： | 3/18頁 |
| 文件大?。?/td> | 0K |
| 描述： | EVAL KIT FOR MAX4411 |
| 標準包裝： | 1 |
MAX4411
80mW, Fixed-Gain, DirectDrive, Stereo
Headphone Amplifier with Shutdown
______________________________________________________________________________________
11
duced by two different capacitor dielectric types.
Note that below 100Hz, THD+N increases rapidly.
The combination of low-frequency attenuation and fre-
quency-dependent distortion compromises audio repro-
duction in portable audio equipment that emphasizes
low-frequency effects such as multimedia laptops, as
well as MP3, CD, and DVD players. By eliminating the
DC-blocking capacitors through DirectDrive technology,
these capacitor-related deficiencies are eliminated.
Charge Pump
The MAX4411 features a low-noise charge pump. The
320kHz switching frequency is well beyond the audio
range, and thus does not interfere with the audio sig-
nals. The switch drivers feature a controlled switching
speed that minimizes noise generated by turn-on and
turn-off transients. By limiting the switching speed of the
charge pump, the di/dt noise caused by the parasitic
bond wire and trace inductance is minimized. Although
not typically required, additional high-frequency noise
attenuation can be achieved by increasing the size of
C2 (see Typical Application Circuit).
Shutdown
The MAX4411 features two shutdown controls allowing
either channel to be shut down or muted independently.
SHDNL controls the left channel while SHDNR controls
the right channel. Driving either SHDN_ low disables
the respective channel, sets the driver output imped-
ance to 1k
Ω, and reduces the supply current. When
both SHDN_ inputs are driven low, the charge pump is
also disabled, further reducing supply current draw to
6A. The charge pump is enabled once either SHDN_
input is driven high.
Click-and-Pop Suppression
In conventional single-supply audio 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, typically half the
supply. Likewise, on shutdown, the capacitor is dis-
charged to GND. This results in a DC shift across the
capacitor, which in turn, appears as an audible transient
at the speaker. Since the MAX4411 does not require
output-coupling capacitors, this does not arise.
Additionally, the MAX4411 features extensive click-and-
pop suppression that eliminates any audible transient
sources internal to the device. The Power-Up/Down
Waveform 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 MAX4411 has a DC bias of typically half the
supply. At startup, the input-coupling capacitor is
charged to the preamplifier’s DC-bias voltage through
the RF of the MAX4411, resulting in a DC shift across
the capacitor and an audible click/pop. Delaying the
rise of the SHDN_ signals 4 to 5 time constants (80ms
to 100ms) based on RIN and CIN, relative to the startup
of the preamplifier, eliminates this click/pop caused by
the input filter.
Applications Information
Power Dissipation
Under normal operating conditions, linear power ampli-
fiers can dissipate a significant amount of power. The
maximum power dissipation for each package is given
in the Absolute Maximum Ratings section under
Continuous Power Dissipation or can be calculated by
the following equation:
where TJ(MAX) is +150°C, TA is the ambient tempera-
ture, and
θJA is the reciprocal of the derating factor in
°C/W as specified in the Absolute Maximum Ratings
section. For example,
θJA of the QFN package is
+59.3°C/W.
The MAX4411 has two power dissipation sources, the
charge pump and the two drivers. If the power dissipa-
tion for a given application exceeds the maximum
allowed for a given package, either reduce VDD,
increase load impedance, decrease the ambient tem-
perature, or add heatsinking to the device. Large
P
TT
DISSPKG MAX
J MAX
A
JA
()
=
θ
ADDITIONAL THD+N DUE
TO DC-BLOCKING CAPACITORS
MAX4411
fig04
FREQUENCY (Hz)
THD+N
(%)
10k
1k
100
0.001
0.01
0.1
1
10
0.0001
10
100k
TANTALUM
ALUM/ELEC
Figure 4. Distortion Contributed by DC-Blocking Capacitors
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| MAX4412ESA+ | 功能描述:運算放大器 - 運放 Low-Cost Low-Power Ultra-Small 3V/5V 500MHz Single-Supply Op Amps with Rail-to-Rail Outputs RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| MAX4412ESA+T | 功能描述:運算放大器 - 運放 Single Low-Cost low-Power Ultra-Small 3V/5V 500MHz Single-Supply OP RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
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