MT88E41

Data Sheet

SEMICMF.019

4

1.0

Functional Description

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

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.

Figure 3 - Differential Input Configuration

C1

R1

C2

R4

R3

R2

R5

IN+

IN-

GS

MT88E41

DIFFERENTIAL INPUT AMPLIFIER

C1 = C2 = 10 nF

R1 = R4 = R5 = 100 k

Ω

R2 = 60k

Ω, R3 = 37.5 kΩ

R3 = (R2R5) / (R2 + R5)

VOLTAGE GAIN

INPUT IMPEDANCE