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| 型号： | TS4972IJT |
| 厂商： | 意法半导体 |
| 元件分类： | 音频放大器 |
| 英文描述： | Aluminum Electrolytic Capacitor; Capacitor Type:General Purpose; Voltage Rating:35VDC; Capacitor Dielectric Material:Aluminum Electrolytic; Operating Temperature Range:-55 C to +105 C; Capacitance:4.7uF RoHS Compliant: Yes |
| 中文描述： | 为1.2W音频功率放大器，具有活性高备用模式 |
| 文件页数： | 22/28页 |
| 文件大小： | 904K |
| 代理商： | TS4972IJT |
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TS4972
22/28
The charge time of Cb is directly proportional to
the internal generator resistance 50k
.
Then, the charge time constant for Cb is
τ
b = 50k
xCb
(s)
As Cb is directly connected to the non-inverting
input (pin 2 & 3) and if we want to minimize, in
amplitude and duration, the output spike on Vout1
(pin 5), Cin must be charged faster than Cb. The
charge time constant of Cin is
τ
in = (Rin+Rfeed)xCin
(s)
Thus we have the relation
τ
in <<
τ
b
(s)
The respect of this relation permits to minimize the
pop and click noise.
Remark : Minimize Cin and Cb has a benefit on
pop and click phenomena but also on cost and
size of the application.
Example : your target for the -3dB cut off
frequency is 100 Hz. With Rin=Rfeed=22 k
,
Cin=72nF (in fact 82nF or 100nF).
With Cb=1μF, if you choose the one of the latest
two values of Cin, the pop and click phenomena at
power supply ON or standby function ON/OFF will
be very small
50 k
x1μF >> 44k
x100nF (50ms >> 4.4ms).
Increasing Cin value increases the pop and click
phenomena to an unpleasant sound at power
supply ON and standby function ON/OFF.
Why Cs is not important in pop and click
consideration
Hypothesis :
Cs = 100μF
Supply voltage = 5V
Supply voltage internal resistor = 0.1
Supply current of the amplifier Icc = 6mA
At power ON of the supply, the supply capacitor is
charged through the internal power supply
resistor. So, to reach 5V you need about five to ten
times the charging time constant of Cs (
τ
s =
0.1xCs (s)).
Then, this time equal 50μs to 100μs <<
τ
b in the
majority of application.
At power OFF of the supply, Cs is discharged by a
constant current Icc. The discharge time from 5V
to 0V of Cs is:
Now, we must consider the discharge time of Cb.
At power OFF or standby ON, Cb is discharged by
a 100k
resistor. So the discharge time is about
τ
b
Disch
≈
3xCbx100k
(s).
In the majority of application, Cb=1μF, then
τ
b
Disch
≈
300ms >> t
dischCs
.
I
Power amplifier design examples
Given :
Load impedance : 8
Output power @ 1% THD+N : 0.5W
Input impedance : 10k
min.
Input voltage peak to peak : 1Vpp
Bandwidth frequency : 20Hz to 20kHz (0, -3dB)
Ambient temperature max = 50°C
SO8 package
First of all, we must calculate the minimum power
supply voltage to obtain 0.5W into 8
. With curves
in fig. 15, we can read 3.5V. Thus, the power
supply voltage value min. will be 3.5V.
Following the maximum power dissipation
equation
with 3.5V we have Pdissmax=0.31W.
Refer to power derating curves (fig. 20), with
0.31W the maximum ambient temperature will be
100°C. This last value could be higher if you follow
the example layout shown on the demoboard
(better dissipation).
The gain of the amplifier in flat region will be:
We have Rin > 10k
. Let's take Rin = 10k
, then
Rfeed = 28.25k
. We could use for Rfeed = 30k
in normalized value and the gain will be Gv = 6.
t
DischCs
= ------------- = 83 ms
Icc
)
W
(
R
Vcc
2
π
2
max
Pdiss
L
2
=
G
V
= V
OUTPP
V
INPP
-------------------- = ----------------------------------- = 5.65
L
P
OUT
V
INPP
相关PDF资料 |
PDF描述 |
|---|---|
| TS4972 | 1.2W AUDIO POWER AMPLIFIER WITH STANDBY MODE ACTIVE HIGH |
| TS4972JT | 1.2W AUDIO POWER AMPLIFIER WITH STANDBY MODE ACTIVE HIGH |
| TS4973IJT | 1.2W TWO AUDIO INPUTS WITH GAIN CONTROL POWER AMPLIFIER WITH STANDBY MODE ACTIVE LOW |
| TS4973 | 1.2W TWO AUDIO INPUTS WITH GAIN CONTROL POWER AMPLIFIER WITH STANDBY MODE ACTIVE LOW |
| TS4974 | 1W Differential Audio Power Amplifier with Up/Down Digital Volume Control Pins |
相关代理商/技术参数 |
参数描述 |
|---|---|
| TS4972JT | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:1.2W AUDIO POWER AMPLIFIER WITH STANDBY MODE ACTIVE HIGH |
| TS4973 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:1.2W TWO AUDIO INPUTS WITH GAIN CONTROL POWER AMPLIFIER WITH STANDBY MODE ACTIVE LOW |
| TS4973EIJT | 功能描述:音频放大器 1.2W 2 audio inputs 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 |
| TS4973IJT | 制造商:STMicroelectronics 功能描述: |
| TS4974 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:1W Differential Audio Power Amplifier with Up/Down Digital Volume Control Pins |
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