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參數(shù)資料
| 型號： | MAX4297EAG |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | Mono/Stereo 2W Switch-Mode (Class-D) Audio Power Amplifiers |
| 中文描述： | 2 W, 2 CHANNEL, AUDIO AMPLIFIER, PDSO24 |
| 封裝： | 5.30 MM, MO-150, SSOP-24 |
| 文件頁數(shù)： | 13/18頁 |
| 文件大?。?/td> | 719K |
| 代理商： | MAX4297EAG |
M
Mono/Stereo 2W Switch-Mode (Class-D)
Audio Power Amplifiers
______________________________________________________________________________________
13
The amplifier
’
s input bias current is low, ±50pA, and does
not affect the choice of feedback resistors. The noise in
the circuit increases as the value of RF increases.
The optimum impedance seen by the inverting input is
between 5k
and 20k
. The effective impedance is
given by (RF
RIN)/(RF + RIN). For values of RF >
50k
, a small capacitor (
≈
3pF) connected across RF
compensates for the pole formed by the input capaci-
tance and the effective resistance at the inverting input.
Soft-Start (Clickless Startup)
The H-bridge is disabled under any of the following
conditions:
SHDN
low
H-bridge current exceeds the 1A current limit
Thermal overload
Undervoltage lockout
The circuit re-enters normal operation if none of the
above conditions are present. A soft-start function pre-
vents an audible pop on restart. An external capacitor
connected to SS is charged by an internal 1.2μA cur-
rent source and controls the soft-start rate. V
SS
is held
low while the H-bridge is disabled and allowed to ramp
up to begin a soft-start. Until V
SS
reaches 0.3
V
CC
,
the H-bridge output is limited to a 50% duty cycle,
independent of the input voltage. The H-bridge duty
cycle is then gradually allowed to track the input signal
at a rate determined by the ramp on SS. The soft-start
cycle is complete after V
SS
reaches 0.6
V
CC
.
Input Filter
High-fidelity audio applications require gain flatness
between 20Hz to 20kHz. Set the low-frequency cutoff
point with an AC-coupling capacitor in series with the
input resistor of the amplifier, creating a highpass filter
(Figure 3). Assuming the input node of the amplifier is a
virtual ground, the -3dB point of the highpass filter is
determined by: f
LO
= 1/(2
π
RIN
CIN), where RIN is
the input resistor, and CIN is the AC-coupling capaci-
tor. Choose RIN as described in the
Gain Setting
sec-
tion. Choose CIN such that the corner frequency is
below 20Hz.
Frequency Selection
The MAX4295/MAX4297 have an internal logic-pro-
grammable oscillator controlled by FS1 and FS2 (Table
1). The oscillator can be programmed to frequencies of
125kHz, 250kHz, 500kHz, and 1MHz. The frequency
should be chosen to best fit the application. As a rule of
thumb, choose f
OSC
to be 10 times the audio band-
width. A lower switching frequency offers higher ampli-
fier efficiency and lower THD but requires larger
external filter components. A higher switching frequen-
cy reduces the size and cost of the filter components at
the expense of THD and efficiency. In most applica-
tions, the optimal f
OSC
is 250kHz.
Table 1. Frequency Select Logic
INPUT
CIN
RIN
RF
AOUT
IN
VCM
FS1
0
0
1
1
FS2
0
1
0
1
FREQUENCY (Hz)
125k
250k
500k
1M
Figure 3. Input Amplifier Configuration
V
IN
V
RAMP
+5V
V
OUT
0
Figure 2. PWM Waveforms
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX4297EAG+ | 功能描述:音頻放大器 Integrated Circuits (ICs) 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 |
| MAX4297EAG+T | 功能描述:音頻放大器 Integrated Circuits (ICs) 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 |
| MAX4297EAG-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 |
| MAX4297EVKIT | 制造商:Maxim Integrated Products 功能描述: |
| MAX4297EWG | 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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