MT88E43B
Extended Voltage Calling Number
Identification Circuit 2
CMOS
Data Sheet
Features
•
Compatible with:
• British Telecom (BT) SIN227 & SIN242
•
•
•
•
•
•
•
•
•
•
•
•
U.K.’s Cable Communications Association
(CCA) specification TW/P&E/312
Bellcore GR-30-CORE (formerly known as
TR-NWT-000030) & SR-TSV-002476
Ordering Information
MT88E43BE
24 Pin PDIP
MT88E43BS
24 Pin SOIC
MT88E43BSR 24 Pin SOIC
MT88E43BS1 24 Pin SOIC*
MT88E43BSR1 24 Pin SOIC*
*Pb Free Matte Tin
-40°C to +85°C
•
•
•
•
Feature phones, including Analog Display
Services Interface (ADSI) phones
Phone set adjunct boxes
FAX and answering machines
Database query and Computer Telephony
Integration (CTI) systems
Tubes
Tubes
Tape & Reel
Tubes
Tape & Reel
April 2006
Bellcore "CPE Alerting Signal (CAS)" and BT
"Idle State Tone Alert Signal" detection
Ring and line reversal detection
1200 baud Bell 202 and CCITT V.23 Frequency
Shift Keying (FSK) demodulation
3 or 5 V
±10%
supply voltage
High input sensitivity (-40 dBV Tone and FSK
Detection)
Selectable 3-wire data interface (microcontroller
or MT88E43 controlled)
Low power CMOS with powerdown mode
Input gain adjustable amplifier
Carrier detect status output
Uses 3.58 MHz crystal
Description
The MT88E43 Calling Number Identification Circuit 2
(ECNIC2) is a low power CMOS integrated circuit
intended for receiving physical layer signals
transmitted according to BT (British Telecom) SIN227
& SIN242, the U.K.’s CCA (Cable Communications
Association) TW/P&E/312 and Bellcore GR-30-CORE
& SR-TSV-002476 specifications. The MT88E43 is
suitable for applications using a fixed voltage power
source between 3 and 5 V
±10%.
FSKen
MODE
DCLK
DATA
DR
Applications
•
BT Calling Line Identity Presentation (CLIP), CCA
CLIP, and Bellcore Calling Identity Delivery (CID)
systems
IN+
IN-
GS
+
-
Anti-alias
Filter
FSK Bandpass
Filter
FSK
Demodulator
Data Timing
Recovery
To internal
cct.
VRef
CAP
PWDN
Bias
Generator
Carrier
Detector
CD
Interrupt
Generator
INT
Alert Signal High
Tone Filter
To internal cct.
Alert Signal Low
Tone Filter
Oscillator
Tone
Detection
Algorithm
Guard
Time
StD
St/GT
ESt
VDD
VSS
OSCin OSCout TRIGin
TRIGRC
TRIGout
Figure 1 - Functional Block Diagram
1
Zarlink Semiconductor Inc.
Zarlink, ZL and the Zarlink Semiconductor logo are trademarks of Zarlink Semiconductor Inc.
Copyright 1997-2006, Zarlink Semiconductor Inc. All Rights Reserved.
MT88E43B
Data Sheet
IN+
IN-
GS
VRef
CAP
TRIGin
TRIGRC
TRIGout
MODE
OSCin
OSCout
VSS
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
VDD
St/GT
ESt
StD
INT
CD
DR
DATA
DCLK
FSKen
PWDN
IC
Figure 2 - Pin Connections
Pin Description
Pin #
1
2
3
4
5
6
7
Name
IN+
IN-
GS
V
Ref
CAP
Description
Non-inverting Input
of the internal opamp.
Inverting Input
of the internal opamp.
Gain Select (Output)
of internal opamp. The opamp’s gain should be set according to the
nominal Vdd of the application using the information in Figure 10.
Reference Voltage (Output).
Nominally V
DD
/2
. It is used to bias the input opamp.
Capacitor.
A 0.1
µF
decoupling capacitor should be connected across this pin and V
SS
.
TRIGin
Trigger Input.
Schmitt trigger buffer input. Used for line reversal and ring detection.
TRIGRC
Trigger RC (Open Drain Output/Schmitt Input).
Used to set the (RC) time interval from
TRIGin going low to TRIGout going high. An external resistor connected to V
DD
and capacitor
connected to V
SS
determine the duration of the (RC) time interval.
TRIGout
Trigger Out (CMOS Output).
Schmitt trigger buffer output. Used to indicate detection of line
reversal and/or ringing.
MODE
3-wire interface: Mode Select (CMOS Input).
When low, selects interface mode 0. When high,
selects interface mode 1. See pin 16 (DCLK) description to understand how MODE affects the
DCLK pin.
Oscillator Input.
A 3.579545 MHz crystal should be connected between this pin and OSCout. It
may also be driven directly from an external clock source.
8
9
10
11
12
13
14
OSCin
OSCout
Oscillator Output.
A 3.579545 MHz crystal should be connected between this pin and OSCin.
When OSCin is driven by an external clock, this pin should be left open.
V
SS
IC
Power Supply Ground.
Internal Connection.
Must be connected to V
SS
for normal operation.
PWDN
Power Down (Schmitt Input).
Active high. When high, the device consumes minimal power by
disabling all functionality except TRIGin, TRIGRC and TRIGout. Must be pulled low for device
operation.
FSKen
FSK Enable (CMOS Input).
Must be high for FSK demodulation. This pin should be set low to
prevent the FSK demodulator from reacting to extraneous signals (such as speech, alert signal
and DTMF which are all in the same frequency band as FSK).
DCLK
3-wire Interface: Data Clock (CMOS Input/Output).
In mode 0 (MODE pin low), this pin is an
output. In mode 1 (MODE pin high), this pin is an input.
15
16
2
Zarlink Semiconductor Inc.
MT88E43B
Pin Description
Pin #
17
18
Name
DATA
DR
Description
Data Sheet
3-wire Interface: Data (CMOS Output).
In mode 0 data appears at the pin once demodulated.
In mode 1 data is shifted out on the rising edge of the microcontroller supplied DCLK.
3-wire Interface: Data Ready (CMOS Output).
Active low. In mode 0 this output goes low after
the last DCLK pulse of each data word. This identifies the 8-bit word boundary on the serial
output stream. Typically, DR is used to latch 8-bit words from a serial-to-parallel converter into a
microcontroller. In mode 1 this pin will signal the availability of data.
Carrier Detect (CMOS Output).
Active low. A logic low indicates the presence of in-band signal
at the output of the FSK bandpass filter.
Interrupt (Open Drain Output).
Active low. It is active when TRIGout or DR is low, or StD is
high. This output stays low until all three signals have become inactive.
Dual Tone Alert Signal Delayed Steering Output (CMOS Output).
When high, it indicates
that a guard time qualified alert signal has been detected.
Dual Tone Alert Signal Early Steering Output (CMOS Output).
Alert signal detection output.
Used in conjunction with St/GT and external circuitry to implement the detect and non-detect
guard times.
Dual Tone Alert Signal Steering Input/Guard Time (Analog Input/CMOS Output).
A voltage
greater than V
TGt
(see Figure 4) at the St/GT pin causes the device to indicate that a dual tone
has been detected by asserting StD high. A voltage less than V
TGt
frees the device to accept a
new dual tone.
Positive Power Supply.
19
20
21
22
CD
INT
StD
ESt
23
St/GT
24
V
DD
The MT88E43 provides all the features and functions offered by Zarlink’s MT8841 (CNIC), including 1200 baud Bell
202 and CCITT V.23 FSK demodulation. The 3-wire serial data interface provided by CNIC has been enhanced to
operate in two modes. In the CNIC compatible mode data transfer is initiated by the device. A second mode allows
a microcontroller to extract 8-bit data words from the device. Furthermore, the MT88E43 offers Idle State Tone Alert
Signal and line reversal detection capability for BT’s CLIP, ring burst detection for the U.K.’s CCA’s CLIP, and ring
and CAS detection for Bellcore’s CID.
Functional Overview
The MT88E43, Extended Voltage Calling Number Identification Circuit 2 (ECNIC2) is a device compatible with BT,
the U.K.’s CCA and Bellcore specifications. As shown in Figure 1, the MT88E43 provides an FSK demodulator as
well as a 3-wire serial interface similar to that of it’s predecessor, the MT8841 (CNIC). The 3-wire interface has
been enhanced to provide two modes of operation - a mode whereby data transfer is initiated by the device and a
mode whereby data transfer is initiated by an external microcontroller.
In addition to supporting all the features and functions of the MT8841, the MT88E43 also provides line reversal
detection, ring detection and dual tone alert signal/CAS detection. These new functions eliminate some external
circuitry previously required with the MT8841.
The MT88E43 is compatible with the caller identity specifications of BT, the U.K.’s CCA, and Bellcore.
BT specifications SIN227 and SIN242 describe the signalling mechanism between the network and the Terminal
Equipment (TE) for the Caller Display Service (CDS). CDS provides Calling Line Identity Presentation (CLIP),
which delivers to an on hook (idle state) TE the identity of an incoming caller before the first ring.
An incoming CDS call is indicated by a polarity reversal on the A and B wires (see Figure 3), followed by an Idle
State Tone Alert Signal. Caller ID FSK information is then transmitted in CCITT V.23 format. MT88E43 can detect
the line reversal, tone alert signal, and demodulate the incoming CCITT V.23 FSK signals.
3
Zarlink Semiconductor Inc.
MT88E43B
Data Sheet
The U.K.’s CCA specification TW/P&E/312 proposes an alternate CDS TE interface. According to TW/P&E/312,
data is transmitted after a single burst of ringing rather than before the first ringing cycle (as specified in the BT
standards). The Idle State Tone Alert Signal is not required as it is replaced by a single ring burst. MT88E43 has the
capability to detect the ring burst. It can also demodulate either Bell-202 or CCITT V.23 FSK data following the ring
burst. The U.K.’s CCA specifies that data can be transmitted in either format.
Bellcore specification GR-30-CORE is the generic requirement for transmitting asynchronous voiceband data to
Customer Premises Equipment (CPE). Another Bellcore specification SR-TSV-002476 describes the same
requirements from the CPE’s perspective. The data transmission technique specified in both documents is
applicable in a variety of services like Calling Number Delivery (CND), Calling Name Delivery (CNAM) and Calling
Identity Delivery on Call Waiting (CIDCW) - services promoted by Bellcore.
In CND/CNAM service, information about a calling party is embedded in the silent interval between the first and
second ring burst. The MT88E43 detects the first ring burst and can then be setup to receive and demodulate the
incoming Bell-202 FSK data. The device will output the demodulated data onto a 3-wire serial interface.
In CIDCW service, information about an incoming caller is sent to the subscriber, while he/she is engaged in
another call. A CPE Alerting Signal (CAS) indicates the arrival of CIDCW information. The MT88E43 can detect the
alert signal and then be setup to demodulate incoming FSK data containing CIDCW information.
Functional Description
Detection of CLIP/CID Call Arrival Indicators
The circuit in Figure 3 illustrates the relationship between the TRIGin, TRIGRC and TRIGout signals. Typically, the
three pin combination is used to detect an event indicated by an increase of the TRIGin voltage from V
SS
to above
the Schmitt trigger high going threshold V
T+
(see DC electrical characteristics).
Figure 3 shows a circuit to detect any one of three CLIP/CID call arrival indicators: line reversal, ring burst and
ringing.
V
DD
V3
R1=499K
R3=200K
R4=301K
TRIGin
MT88E43
max V
T+
= 0.68 V
DD
min VT+ = 0.48 V
DD
Tip/A
C1=100nF
V1
Ring/B
Notes:
The application circuit must ensure that,
V
TRIGin
>max V
T+
where max V
T+
=3.74V @V
DD
=5.5V.
Tolerance to noise between A/B and V
SS
is:
max V
noise
= (min V
T+
)/0.30+0.7 =5.6Vrms @4.5V V
DD
where min V
T+
= 2.16V @V
DD
=4.5V.
Suggested R
5
C
3
component values:
R5 from 10KΩ to 500KΩ
C3 from 47nF to 0.68µF
An example is C3=220nF, R5=150KΩ; TRIGout low
from 21.6ms to 37.6ms after TRIGin Signal stops
triggering the circuit.
R2=499K
V4
R5=150K
C2=100nF
V2
TRIGRC
To determine values for C3 and R5:
R5C3=-t / ln(1-V
TRIGRC
/V
DD
)
C3=220nF
TRIGout
To Microcontroller
Figure 3 - Circuit to Detect Line Reversal, Ring Burst and Ringing
4
Zarlink Semiconductor Inc.
MT88E43B
1. Line Reversal Detection
Data Sheet
Line reversal, or polarity reversal on the A and B wires indicates the arrival of an incoming CDS call, as specified in
SIN227. When the event (line reversal) occurs, TRIGin rises past the high going Schmitt threshold V
T+
and
TRIGout, which is normally high, is pulled low. When the event is over, TRIGin falls back to below the low going
Schmitt threshold V
T-
and TRIGout returns high. The components R5 and C3 (see Figure 3) at TRIGRC ensure a
minimum TRIGout low interval.
In a TE designed for CLIP, the TRIGout high to low transition may be used to interrupt or wake-up the
microcontroller. The controller can thus be put into power-down mode to conserve power in a battery operated TE.
2. Ring Burst Detection
CCA does not support the dual tone alert signal (refer to Dual Tone Alert Signal Detection section). Instead, CCA
requires that the TE be able to detect a single burst of ringing (duration 200-450 ms) that precedes CLIP FSK data.
The ring burst may vary from 30 to 75 Vrms and is approximately 25 Hz.
Again in a TE designed for CCA CLIP, the TRIGout high to low transition may be used to interrupt or wake-up the
microcontroller. The controller can thus be put into power-down mode to conserve power in a battery operated TE.
3. Ring Detection
In Bellcore’s CND/CNAM scheme, the CID FSK data is transmitted between the first and second ringing cycles.
The circuit in Figure 3 will generate a ring envelope signal (active low) at TRIGout for a ring voltage of at least
40 Vrms. R5 and C3 filter the ring signal to provide an envelope output.
The diode bridge shown in Figure 3 works for both single ended and balanced ringing. A fraction of the ring voltage
is applied to the TRIGin input. When the voltage at TRIGin is above the Schmitt trigger high going threshold V
T+
,
TRIGRC is pulled low as C3 discharges. TRIGout stays low as long as the C3 voltage stays below the minimum
V
T+
.
In a CPE designed for CND/CNAM, the TRIGout high to low transition may be used to interrupt or wake-up the
microcontroller. The controller can thus be put into power-down mode to conserve power.
If precise ring duration determination is critical, capacitor C3 in Figure 3 may be removed. The microcontroller will
now be able to time the ring duration directly. The result will be that TRIGout will be low only as long as the ringing
signal is present. Previously the RC time constant would cause only one interrupt.
Dual Tone Alert Signal Detection
The BT on hook (idle state) caller ID scheme uses a dual tone alert signal whose characteristics are shown in Table
1.
Bellcore specifies a similar dual tone alert signal called CPE Alerting Signal (CAS) for use in off-hook data
transmission (see Table 1). Bellcore states that the CPE should be able to detect the CAS in the presence of near
end speech. The CAS detector should also be immune to imitation from near and far end speech.
In the MT88E43 the dual tone alert signal is separated into a high and a low tone by two bandpass filters. A
detection algorithm examines the two filter outputs to determine the presence of a dual tone alert signal. The ESt
pin goes high when both tones are present. Note that ESt is only a preliminary indication. The indication must be
sustained over the tone present guard time to be considered valid. Tone present and tone absent guard times can
be implemented with external RC components. The tone present guard time rejects signals of insufficient duration.
The tone absent guard time masks momentary detection dropout once the present guard time has been satisfied.
StD is the guard time qualified detector output.
5
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