EV6021 Datasheet, PDF (12/28 Pages) CML Microcircuits – User Manual

Evaluation Kit for CMX602B
EV6021
1.6 Detailed Description
1.6.1 Hardware Description - Evaluation Board
1.6.1.1
Line Protection
Line protection is provided by R1 (47Ω), 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 (827Ω), 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 240Ω 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 2k2Ω.
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 600Ω.
For complex matching fit C11 (310nF), R16 (370Ω), 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.
 2000 Consumer Microcircuits Limited
12
UM6021/4