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參數(shù)資料
| 型號(hào)： | AS2520B |
| 廠商： | AUSTRIAMICROSYSTEMS AG |
| 英文描述： | Telephone Speech Circuit with Loudhearing and Handsfree |
| 中文描述： | 電話語(yǔ)音電路Loudhearing和免提 |
| 文件頁(yè)數(shù)： | 8/14頁(yè) |
| 文件大小： | 96K |
| 代理商： | AS2520B |
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Preliminary
AS2520/21/20B/21B
Rev. 5.1
Page 8
May 1999
The speech compression allows a higher gain in the
transmit channel, i.e. the microphone gets more
sensitive at low sound pressure levels on the
microphone, which enables the user to move further
away from the telephone. This means that a constant
signal is provided on the line practical independent of
the microphone signal level. Any reduction of gain by
the compressor in the transmit channel will
automatically be given to the receive channel.
Switching Converter
The ac ringing signal is utilised to extract the power
necessary to the tone ringer circuit. A switch mode
power supply is used to obtain a high efficiency dc
conversion.
This approach allows the use of the same
loudspeaker and amplifiers for both loudhearing and
tone ringing. It also allows an acoustic feedback of
the melodies during programming with the same
sound pressure level as during ringing.
When a ringing signal is applied, PD is pulled high
and the oscillator is enabled. The switching converter
is controlled by the output CM, which is turned high
and low with a duty cycle controlled by the voltage at
V
PP
.
When off-hook the switching converter has a high
impedance (CM low) to avoid any influence on the
transmission and on pulse dialling.
The smoothing capacitor should be in the range of 10
to 68 nF. The choke coil must have an inductance of
>1mH and a dc resistance of < 15 ohm.
CM
V
PP
Vss
P
2.2 mH
BC
327
470 μ
La
Lb
1μ5
1μ5
510
510
5k6
33 n
10 k
A
5V1
V
PP
BC
547
30V
Figure 7: Switching Converter
Tone Input
The tone input is a digital input in ringing mode and
during melody feedback. The digital melody signal
(PDM = pulse density modulation) is directly applied
to the TI input (see also application notes for further
details).
During DTMF dialling the DTMF signal is applied
through a capacitor to the TI input and will be fed to
the line (pin LI) and to the receive output (RO) as
confidence tone.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| AS2520T | Telephone Speech Circuit with Loudhearing and Handsfree |
| AS2521B | Telephone Speech Circuit with Loudhearing and Handsfree |
| AS2520BP | Telephone Speech Circuit with Loudhearing and Handsfree |
| AS2520BT | Telephone Speech Circuit with Loudhearing and Handsfree |
| AS2521BP | Telephone Speech Circuit with Loudhearing and Handsfree |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AS2520BP | 制造商:AMSCO 制造商全稱:austriamicrosystems AG 功能描述:Telephone Speech Circuit with Loudhearing and Handsfree |
| AS2520BT | 制造商:AMSCO 制造商全稱:austriamicrosystems AG 功能描述:Telephone Speech Circuit with Loudhearing and Handsfree |
| AS2520P | 制造商:AMSCO 制造商全稱:austriamicrosystems AG 功能描述:Telephone Speech Circuit with Loudhearing and Handsfree |
| AS2520T | 制造商:AMSCO 制造商全稱:austriamicrosystems AG 功能描述:Telephone Speech Circuit with Loudhearing and Handsfree |
| AS2521 | 制造商:AMSCO 制造商全稱:austriamicrosystems AG 功能描述:Telephone Speech Circuit with Loudhearing and Handsfree |
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