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参数资料
| 型号： | TS4872IJT |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 音频／视频放大 |
| 英文描述： | 1 W, 1 CHANNEL, AUDIO AMPLIFIER, PBGA8 |
| 封装： | FCP-8 |
| 文件页数： | 16/29页 |
| 文件大小： | 1012K |
| 代理商： | TS4872IJT |
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Obsolete
Product(s)
- Obsolete
Product(s)
TS4872
23/29
NO
T
F
O
R
NEW
D
E
SIGN
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=1F, 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
x1F >> 44kx100nF (50ms >> 4.4ms).
Increase 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 = 100
F
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 (
τs =
0.1xCs (s)).
Then, this time equal 50s to 100s <<
τb 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
τbDisch ≈ 3xCbx100k (s).
In the majority of application, Cb=1F, then
τbDisch≈300ms >> tdischCs.
■ 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
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.
Referring 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.
In lower frequency we want 20 Hz (-3dB cut off
frequency). Then
So, we could use for Cin a 1F capacitor value that
gives 16Hz.
In Higher frequency we want 20kHz (-3dB cut off
frequency). The Gain Bandwidth Product of the
TS4872 is 2MHz typical and doesn't change when
the amplifier delivers power into the load.
The first amplifier has a gain of
and the theoretical value of the -3dB cut-off higher
frequency is 2MHz/3 = 660kHz.
We can keep this value or limit the bandwidth by
adding a capacitor Cfeed, in parallel on Rfeed.
tDischCs =
5Cs
Icc
-------------- = 83 ms
)
W
(
R
Vcc
2
max
Pdiss
L
2
π
=
G V =
VOUTPP
VINPP
--------------------- =
22 RL P OUT
VINPP
------------------------------------ = 5.65
CIN =
1
2
π RinFCL
------------------------------ = 795nF
Rfee d
Rin
----------------- = 3
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TS487-2IQT | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Amplifier. Other |
| TS487-2IST | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Amplifier. Other |
| TS487-4 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:100mW STEREO HEADPHONE AMPLIFIER WITH STANDBY MODE |
| TS487-4IQT | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Amplifier. Other |
| TS487-4IST | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Amplifier. Other |
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