CMX612 参数 Datasheet PDF下载

Calling Line Identifier with VMWI

CMX612

1.5

1.5.1

General Description

Mode Control Logic

The CMX612's operating mode and the source of the DET and IRQN outputs are determined by the logic

levels applied to the MODE 1 and MODE 2 input pins;

MODE 1

0

MODE 2

0

Mode

Tone Alert Detect

DET o/p from

Tone Alert Signal

Detection.

CAS tones present.

FSK Level Detection.

FSK present.

IRQN o/p from

Valid ‘off-hook’ CAS or

Ring or Line Polarity

Reversal Detection.

Ringing Signal present.

FSK Data Retiming [1] or

Ring or Line Polarity

Reversal Detection.

Ringing Signal present.

Ring or Line Polarity

Reversal Detection.

Ringing Signal present.

Valid dial tone detected.

0

1

FSK Receive

1

0

'Zero-Power'

1

1

Dial Tone Detect

Ring or Line Polarity

Reversal Detection.

Ringing Signal present.

Dial Tone Signal Detection.

Both tones present.

[1] If enabled.

In 'Zero-Power' mode, power is removed from all of the internal circuitry except for the Ring or Line

Polarity Reversal Detector and the DET and IRQN outputs.

1.5.2

Input Signal Amplifiers

These amplifiers can be used to convert the balanced FSK, Tone Alert and VMWI signals received over

the telephone line to an unbalanced signal of the correct amplitude for the FSK receiver, Tone Alert and

Dial Tone Detector circuits.

Figure 3a : Input Signal Amplifier, balanced input configuration

The design equations for this circuit are;

Differential voltage gain VAOP / V(b-a) = R8/R6

R6 = R7 = 470kΩ

R10 = 160kΩ

R9 = R8 x R10 / (R8 - R10)

The target differential voltage gain depends on the expected signal levels between the A and B wires and

the CMX612's internal threshold levels, which are proportional to the supply voltage.

©

2002 Consumer Microcircuits Limited

7

D/612/3