Evaluation Kit for CMX602B

EV6021

 2000 Consumer Microcircuits Limited

12

UM6021/4

1.6

Detailed Description

1.6.1

Hardware Description - Evaluation Board

1.6.1.1

Line Protection

Line protection is provided by R1 (47

Ω), R2 (47Ω), and D1 (Philips BR211 series 140V). These

components are not fitted, but suitable values for UK applications are suggested in brackets. Wire

links which bypass R1 and R2 will need to be removed if these resistors are fitted.

1.6.1.2

AC or DC Load

An ac or dc load is provided by R4 (827

Ω), R6 (1386Ω) and C3 (139nF). These components are not

fitted, but suitable values for UK applications are suggested in brackets. This load is switched in by

TRI0. An LED is illuminated when this occurs.

1.6.1.3

Wetting Pulse

A wetting pulse load is provided by R7, which is not fitted. For UK applications, a suitable value may

be in the region of 240

Ω to 350Ω. The wetting pulse is switched in by TR9. An LED is illuminated

when this occurs.

1.6.1.4

External Phone

A second RJ11 socket, J2, is provided for an external telephone when the EV6021 is set to

demonstrate adjunct box functions. When muted/disabled an LED marked ‘XPHONE MUTE’ is

illuminated.

Note that this relay is normally closed, so do not connect a telephone to the external phone socket

J2 when running feature phone demonstrations.

1.6.1.5

Transformer and Op-Amp Hybrid / 2- to 4-wire interface.

The transformer and op-amp hybrid (formed by U3 A and B) are connected to the phone line by relay

RLY2. When energised an adjacent LED is illuminated.

An off-hook dc load, for feature phone mode, is provided by R8, factory set to 2k2

Ω.

Line impedance matching is required in order to place signals on the line (acknowledgement tone of

type 2 / off-hook / cidcw sequences) and to be able to send and receive speech and other signals

(feature phone demonstration).

Two impedance matching options are available, resistive or complex, which can be selected using

switch SW1.

For resistive matching R21 is factory set to 600

Ω.

For complex matching fit C11 (310nF), R16 (370

Ω), R19 (620Ω). Suggested values for BT

applications are given in brackets.

R8 and R21 are socketed for easy removal and replacement.

Alternatively, matching components could be fitted across test points TP3 and TP4.

Access to hybrid signals is provided as follows:

The hybrid receive output (Rx = remote voice) is located on test point TP5.

The hybrid transmit output (Tx = local voice) is located on test point TP4.

1.6.1.6

Local Speech Paths

When emulating a feature phone, a muteable local speech path is available. A speech signal may be

input at either testpoint TP6 or jack socket J4. Alternatively with jumper JP1 fitted the local voice can

come from a telephone handset (not provided) connected to socket J3.

When muted an LED

marked ‘L’CAL MUTE’ is enabled.

Note that the local speech path has a gain of

≈12dB.