CMOS
MT8841
Calling Number Identification Circuit
ISSUE 4
May 1995
Features
Ordering Information
•
•
1200 baud BELL 202 and CCITT V.23
Frequency Shift Keying (FSK) demodulation
MT8841AE
MT8841AS
MT8841AN
16 Pin Plastic DIP
16 Pin SOIC
20 Pin SSOP
Compatible with Bellcore TR-NWT-000030 and
SR-TSV-002476
-40 °C to +85 °C
•
•
High input sensitivity: -36dBm
Simple serial 3-wire data interface eliminating
the need for a UART
Description
The MT8841 Calling Number Identification Circuit
(CNIC) is a CMOS integrated circuit providing an
interface to various calling line information delivery
services that utilize 1200 baud BELL 202 or CCITT
V.23 FSK voiceband data transmission schemes.
The CNIC receives and demodulates the signal and
outputs data into a simple 3-wire serial interface.
•
•
•
•
Power down mode
Internal gain adjustable amplifier
Carrier detect status output
Uses 3.579545 MHz crystal or ceramic
resonator
Single 5V power supply
•
•
Low power CMOS technology
Typically, the FSK modulated data containing
information on the calling line is sent before alerting
the called party or during the silent interval between
the first and second ring using either CCITT V.23
recommendations or Bell 202 specifications.
Applications
•
Calling Number Delivery (CND), Calling Name
Delivery (CNAM) and Calling Identity on Call
Waiting (CIDCW) features of Bellcore CLASSSM
service
The CNIC accepts and demodulates both CCITT
V.23 and BELL 202 signals. Along with serial data
and clock, the CNIC provides a data ready signal to
indicate the reception of every 8-bit character sent
from the Central Office. The received data can be
processed externally by a microcontroller, stored in
memory, or displayed as is, depending on the
application.
•
•
•
•
•
Feature phones
Phone set adjunct boxes
FAX machines
Telephone Answering machines
Database query systems
GS
DATA
Receive
Bandpass
Filter
Data and Timing
IN-
-
DR
FSK
Demodulator
Recovery
+
IN+
DCLK
CAP
Bias
Generator
Carrier
Detector
V
Ref
CD
to other
circuits
Clock
Generator
V
V
IC1 IC2
PWDN
OSC1 OSC2
SS
DD
Figure 1 - Functional Block Diagram
CLASSSM is a service mark of Bellcore
5-11