Datasheet > AS2521P

AS2521P

更新时间： 2024-02-27 19:06:09

品牌	Logo	应用领域
艾迈斯 - AMSCO		电话
页数	文件大小	规格书
14页	99K
描述
Telephone Speech Circuit with Loudhearing and Handsfree

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技术参数
数据手册

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AS2521P 技术参数

生命周期：	Obsolete	零件包装代码：	SOIC
包装说明：	SOP,	针数：	28
Reach Compliance Code：	unknown	HTS代码：	8542.39.00.01
风险等级：	5.82	JESD-30 代码：	R-PDSO-G28
功能数量：	1	端子数量：	28
封装主体材料：	PLASTIC/EPOXY	封装代码：	SOP
封装形状：	RECTANGULAR	封装形式：	SMALL OUTLINE
认证状态：	Not Qualified	标称供电电压：	5 V
表面贴装：	YES	电信集成电路类型：	TELEPHONE SPEECH CIRCUIT
端子形式：	GULL WING	端子位置：	DUAL

AS2521P 数据手册

Preliminary

AS2520/21/20B/21B

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.

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.

1µ5

510

5k6

510

327

1µ5

33 n

30V

10 k

Switching Converter

547

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.

2.2 mH

470 µ

VPP

5V1

VssP

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.

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).

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.

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.

When off-hook the switching converter has a high

impedance (CM low) to avoid any influence on the

transmission and on pulse dialling.

Rev. 5.1

Page 8

May 1999

1...5 6 789 10 11...14

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