FX602 查看數據表（PDF） - CML Microsystems Plc

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FX602

Calling line identifier

CML Microsystems Plc 

Calling Line Identifier

FX602

1.5 General Description

1.5.1 Mode Control Logic

The FX602's operating mode and the source of the DET and IRQN outputs are determined by the logic levels

applied to the MODE and ZP input pins;

ZP MODE

Mode

0

0 Tone Alert Detect

0

1 FSK Receive

DET o/p from

Tone Alert Signal

Detection

FSK Level Detector

1

0 'Zero-Power'

1

1 'Zero-Power'

Ring or Line Polarity

Reversal Detector.

Ring or Line Polarity

Reversal Detector.

IRQN o/p from

End of Tone Alert Signal.

Ring or Line Polarity

Reversal Detector.

FSK Data Retiming [1].

Ring or Line Polarity

Reversal Detector.

Ring or Line Polarity

Reversal Detector.

-

[1] If enabled.

In the 'Zero-Power' modes, 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 Amplifier

This amplifier is used to convert the balanced FSK and Tone Alert signals received over the telephone line to

an unbalanced signal of the correct amplitude for the FSK receiver and Tone Alert 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

FX602's internal threshold levels, which are proportional to the supply voltage.

The FX602 has been designed to meet the applicable specifications with R8 = 470kΩ at VDD = 3.3V nominal,

rising to 680kΩ at VDD = 5.0V, and R9 should be 240kΩ at VDD = 3.3V and 200kΩ at VDD = 5.0V as shown in

section 1.4 and Fig 3c.

© 1998 Consumer Microcircuits Limited

7

D/602/7

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