MT88E45
Data Sheet
IN+
IN-
R
C
IN
GS
R
F
Voltage Gain
(AV) = RF / RIN
VREF
Highpass Corner Frequency
f-3dB = 1/(2πRINC)
Figure 3 - Single Ended Input Configuration
R1
R4
IN+
IN-
C1
C2
R5
GS
R2
R3
VREF
Differential Input Amplifier
C1 = C2
R1 = R4 (For unity gain R5= R4)
R3 = (R2R5) / (R2 + R5)
Voltage Gain
Highpass Corner Frequency
(A diff) = R5/R1
V
f
-3dB = 1/(2πR1C1)
Input Impedance
R12 + (1/ωC)2
(Z diff) = 2
IN
Figure 4 - Differential Input Configuration
CAS Detection
In North America, CAS is used in off-hook signalling only. In Europe (ETSI) it is used in off-hook signalling, and by
BT in both on and off-hook signalling. ETSI calls it the Dual Tone Alerting Signal (DT-AS). Although the ETSI on-
hook standard contains a DT-AS specification, BT is the only administration known to employ CAS in on-hook
signalling. (BT calls it Tone Alert Signal.) The CAS/DT-AS characteristics are summarized in Table 3.
BTc
2130 Hz and 2750 Hz
Bellcorea
ETSIb
(Off-hook = ‘Loop State’)
(On-hook = ‘Idle State’)
CAS/DT-AS Characteristics
(Off-hook only)
(Off-hook)
Frequency Tolerance
Signal Level (per tone)
Reject Level (per tone)
+/-0.5%
-14 to -32 dBmd
-45 dBm
+/-0.5%
Off-hook: +/-0.6%
On-hook: +/-1.1%
+0.22 to -37.78 dBm
(-2 to -40 dBV)
On-hook: -43.78 dBm
(-46 dBV)
-9.78 to -32.78 dBm
(-12 to -35 dBVe)
Maximum Twist (V2130Hz/V2750Hz
)
+/-6 dB
+/-6 dB
+/-7 dB
8
Zarlink Semiconductor Inc.
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