MT88E43BS1 Zarlink, MT88E43BS1 Datasheet - Page 7

• Manufacturer Part Number: MT88E43BS1
• Description: Caller ID CMOS 3.58MHz 3.3V/5V 24-Pin SOIC Tube
• Manufacturer: Zarlink

Specifications of MT88E43BS1

• Package: 24SOIC
• Telecommunication Standards Supported: GR-30|SIN227|SIN242|SR-TSV-002476|TR-NWT-000030
• Fabrication Technology: CMOS
• Maximum Data Rate: 1212 Bd
• Typical Operating Supply Voltage: 3.3|5 V
• Typical Supply Current: 3 mA
• Minimum Operating Temperature: -40 °C
• Maximum Operating Temperature: 85 °C
• Operating Frequency: 3.58 MHz

Bellcore states that it is desirable to be able to turn off CAS detection for an off-hook capable CPE. The disable
switch allows the subscriber who disconnects a service that relies on CAS detection (e.g., CIDCW) but retains the
CPE, to turn off the detector and not be bothered by false detection.
When SW1 in Figure 4 is in the B position the guard time circuit is disabled. The detector will still process
CAS/Alerting tones but the MT88E43 will not signal their presence by ensuring StD is low.
BT specifies that the idle state tone alert signal recognition time should not be less than 20 ms when both tones are
used for detection. That is, both tones must be detected together for at least 20 ms before the signal can be
declared valid. This requirement can be met by setting the t
BT also specifies that the TE is required to apply a D.C. wetting pulse and an AC load 15-25 ms after the end of the
alerting signal. If t
at the falling edge of StD. The maximum
t
meet the BT timing requirements.
GA
. Figure 5(a) shows a possible implementation. The values in Figures 9 and 11 (R2=R3=422K, C=0.1µF) will
ABS
=t
DA
+t
GA
is 15 to 25 ms, the D.C. current wetting pulse and the A.C. load can both be applied
From
detector
Tones detected
Figure 4 - Guard Time Circuit Operation
t
DA
is 8ms so t
Zarlink Semiconductor Inc.
MT88E43B
MT88E43
Comparator
+
-
GA
7
V
should be 15-17 ms. Therefore, t
TGt
GP
P
N
(refer to Figure 5) to at least 20 ms.
Q1
Q2
= V
SS
St/GT
V
ESt
StD
DD
A
SW1
C
R
V
B
SS
GP
must be greater than
Data Sheet