MT88E41
1.0
Functional Description
Data Sheet
The MT88E41 Extended Voltage Calling Number Identification Circuit (ECNIC) is a device compatible with the
Bellcore proposal (GR-30-CORE) on generic requirements for transmitting asynchronous voiceband data to
Customer Premises Equipment (CPE) from a serving Stored Program Controlled Switching System (SPCS) or a
Central Office (CO). This data transmission technique is applicable in a variety of services like Calling Number
Delivery (CND), Calling Name Delivery (CNAM) or Calling Identity Delivery on Call Waiting (CIDCW) as specified in
Custom Local Area Signalling Service (CLASS
SM
) calling information delivery features by Bellcore.
With CND, CNAM and CIDCW service, the called subscriber has the capability to display or to store the information
on the calling party which is sent by the CO and received by the ECNIC.
In the CND service, information about a calling party is embedded in the silent interval between the first and second
ring. During this period, the ECNIC receives and demodulates the 1200 baud FSK signal (compatible with Bell-202
specification) and outputs data into a 3-wire serial interface.
In the CIDCW service, information about a second calling party is sent to the subscriber, (while the subscriber is
engaged in another call). During this period, the ECNIC receives and demodulates the FSK signal as in the CND
case.
The ECNIC is designed to provide the data transmission interface required for the above service at the called
subscriber location either in the on-hook case as in CND, or the off-hook case, as in CIDCW. The functional
block diagram of the ECNIC is shown in Figure 1. Note however, for CIDCW applications, a separate CAS (CPE
Alerting Signal) detector is required.
C1
R1
IN+
IN-
C2
R4
R5
GS
R3
R2
V
Ref
DIFFERENTIAL INPUT AMPLIFIER
MT88E41
C1 = C2 = 10 nF
R1 = R4 = R5 = 100 kΩ
R2 = 60kΩ, R3 = 37.5 kΩ
R3 = (R2R5) / (R2 + R5)
INPUT IMPEDANCE
VOLTAGE GAIN
(A
V
diff) = R5/R1
(Z
IN
diff) = 2 R1
2
+ (1/ωC)
2
Figure 3 - Differential Input Configuration
4
SEMICMF.019
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