MT8843 데이터 시트보기 (PDF) - Zarlink Semiconductor Inc

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MT8843

CMOS Calling Number Identification Circuit 2

Zarlink Semiconductor Inc 

MT8843

CPE goes off-hook

TIP/RING

Note 1

PWDN

CAS

A

CPE mutes handset & disables keypad

CPE sends

ACK

Mark

B

C

D

E

Note 5

CPE unmutes handset

and enables keypad

Data

Packet

F

G

FSKen

OSCout

ESt

St/GT

StD (Note 6)

CD

DR

DCLK

DATA

Note 2

tPU

tDP

tDA

tGP

tREC

tGA

VTGt

tABS

Note 7 Note 8

Note 3

tCP

Note 4

tCA

A = 75-85ms

B = 0-100ms

C = 55-65ms

D = 0-500ms

E = 58-75ms

F = feature specific

Data

G ≤ 50ms

Figure 19 - Input and Output Timing for Bellcore Off-hook Data Transmission, e.g., CIDCW

Notes:

1) In a CPE where AC power is not available, the designer may choose to switch over to line power when the CPE goes off-hook and

use battery power while on-hook. The CPE should also be CID (on-hook) capable because TR-NWT-000575 specifies that CIDCW

will be offered only to lines which subscribe to CID.

2) Non-FSK signals such as CAS, speech and DTMF tones are in the same frequency band as FSK. They will be demodulated and

give false data. The FSKen pin should be set low to disable the FSK demodulator when FSK is not expected.

3) FSKen may be set high as soon as the CPE has finished sending the acknowledgment signal ACK. TR-NWT-000575 specifies that

ACK = DTMF D for non-ADSI CPE, A for ADSI CPE.

4) FSKen should be set low when CD has become inactive.

5) In an unsuccessful attempt where the end office does not send the FSK signal, the CPE should unmute the handset and enable the

keypad after this interval.

6) SR-TSV-002476 states that it is desirable that the CPE have an on/off switch for the CAS detector. See SW1 in Figure 4.

7) The total recognition time is tREC = tGP + tDP, where tGP is the tone present guard time and tDP is the tone present detect time (refer

to section “Dual Tone Detection Guard Time” on page 36 for details).VTGt is the comparator threshold (refer to Figure 4).

8) The total tone absent time is tABS = tGA + tDA, where tGA is the tone absent guard time and tDA is the tone absent detect time (refer

to section “Dual Tone Detection Guard Time” on page 36 for details).

VTGt is the comparator threshold (refer to Figure 4).

5-51

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