MT88E45
Data Sheet
FSK
CB0 CB1 CB2
Function
Interface
0/1
0/1
0/1
1
1
0
1
0
1
Set by CB0 FSK Demodulation. Tip/Ring input (GS1) selected. DR/STD is DR.
Set by CB0 Hybrid CAS Detection. Hybrid Receive input (GS2) selected. DR/STD is STD.
Set by CB0 Tip/Ring CAS Detection. Tip/Ring input (GS1) selected. DR/STD is STD.
When the line is off-hook, a Bellcore/TIA Multiple Extension Interworking (MEI)
compatible Type 2 CPE should be able to detect CAS from Tip/Ring while the
CPE is on-hook because it may be the ACK sender. Tip/Ring CAS detection is
also required for BT’s on-hook CLIP.
1
0
0
0
0
0
Mode 1 Power Down. The MT88E45B is disabled and draws virtually no power supply
current.
Mode 0 Reserved for factory testing.
Table 1 - CB0/1/2 Functionality
The number of control bits (CB) required to interface the MT88E45B with the microcontroller depends on the
functionality of the application, as shown in Table 2.
Functionality Group
Controls
Description
FSK (mode 0 or 1) and
CB2
CB0 is hardwired to Vdd or Vss to select the FSK
Hybrid CAS only
interface.
(Non MEI compatible)
CB1 hardwired to Vdd.
The microcontroller uses CB2 to select between the 2
functions.
FSK (mode 0 or 1),
Hybrid CAS,
CB1
CB2
CB0 is hardwired to Vdd or Vss to select the FSK
interface.
Tip/Ring CAS
The microcontroller uses CB1 and CB2 to select between
the 3 functions.
(MEI compatible or BT on-hook CLIP)
FSK (mode 1),
CB1
CB2
CB0 is hardwired to Vdd to select FSK interface mode 1.
The microcontroller uses CB1 and CB2 to select between
the 4 functions.
Hybrid CAS,
Tip/Ring CAS,
Power Down
(MEI compatible or BT on-hook CLIP)
FSK (mode 0), Hybrid CAS,
CB0
CB1
CB2
All 3 pins are required.
Tip/Ring CAS, Power Down
(MEI compatible or BT on-hook CLIP)
Table 2 - Control Bit Functionality Groups
Functional Overview
The MT88E45B is compatible with FSK and FSK plus CAS (CPE Alerting Signal) based Caller ID services around
the world. Caller ID is the generic name for a group of services offered by telephone operating companies whereby
information about the calling party is delivered to the subscriber. In Europe and some other countries Caller ID is
known as Calling Line Identity Presentation (CLIP). ETSI calls CAS ‘Dual Tone Alerting Signal’ (DT-AS), BT calls it
‘Tone Alert Signal’.
Depending on the service, data delivery can occur when the line is in the on-hook or off-hook state. In most
countries the data is modulated in either Bell 202 or CCITT V.23 FSK format and transmitted at 1200 baud from the
serving end office to the subscriber’s terminal. Additionally in off-hook signalling, the special dual tone CAS is used
5
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
