BL34018 Ver la hoja de datos (PDF) - Shanghai Belling Co., Ltd.

Número de pieza

componentes Descripción

Lista de partido

BL34018

BL34018

Shanghai Belling Co., Ltd. 

BL34018

Additionally, the following should be noted:

1) The RCs at Pins 5 and 7 have a dual function in that they affect the sensitivity of the respective log

amplifiers, or in other words, how loud the speech must be in order to get control of the speakerphone

circuit.

2) The RC at Pin 13 also has a dual function in that it determines the sensitivity of the transmit detector

circuit.

3) The volume control affects the switching speed, and the relative response to transmit signals, in the

following manner: When the circuit is in the receive mode, reducing the volume control setting

increases the signal at TXO, and consequently the signal to the TLI pin. Therefore a given signal

at TXI will switch the circuit into the transmit mode quicker at low volume settings.

APPLICATIONS INFORMATION

The BL34018 speakerphone IC is designed to provide the function additionally required

when a speakerphone is added to a standard telephone. The IC provides the necessary relative

level detection and comparison of the speech signals provided by the talkers at the

speakerphone(near end speaker) and at the distant telephone(far end speaker).

The BL34018 is designed for use with an electorate type microphone a 25 ohms speaker, and

has an output power capability of 100mW.All external components surrounding this device are

passive, however, this IC does require additional circuitry to interface the TIp and Ring telephone

lines. Two suggested circuits are shown in the data sheet.

Fig 16 depicts a configuration which does not include a handset, dialer, or ringer. The only

controls are S1(to make the connection to the line),S2(a "privacy" switch),and the volume control.

It is meant to be used in parallel with a normal telephone which has dialing and ringing functions.

Fig 17 depicts a means of providing logic level signal that indicate which mode of operation

the BL34018 is in. Comparator A indicates whether the circuit is in receive or transmit mode and

comparator B indicates(when in transmit/idle mode) whether the circuit is in the transmit or idle

mode. The LM393 dual comparator is chosen because of its low current requirement (<1.0mA),

low voltage requirement (as low as 2.0volts), and low cost .

http://www.belling.com.cn

- 15 -

Total 16 Pages

8/15/2006

Wrote by 2006

Share Link: