SA589 Datasheet, PDF (5/14 Pages) Sames – LD/DTMF SWITCHABLE DIALLERS WITH DEDICATED KEYS FOR 20 MEMORIES

TABLE 2: Dialling mode selection
Select Pin to
V_SS
COL1
Dialling Mode
LD + DTMF
LD + DTMF
COL2
LD + DTMF
COL3
LD + DTMF
COL4
LD only
COL5
DTMF only
COL6
DTMF only
COL7
LD only
V_DD
DTMF only
B:M Ratio
2:1
2:1
3:2
3:2
2:1
-
-
3:2
-
SA589 FAMILY
TBR (msec)
100
270
270
100
-
270
270
-
100
However, if one of the 'LD + DTMF' modes is selected the chip will be in LD mode initially in
the off-hook condition but may be switched to DTMF by pressing either *, */# or TONE key
(depending on the mask variant - see Fig. 2 and page 11), provided that dialling is not in
progress. If any of these keys are pressed during LD dialling, they will be ignored.
Only if * or # are pressed subsequent to switching to DTMF, will * or # be dialled. Only digits
entered prior to a switch to DTMF will subsequently be available for redialling (see Last
Number Redial operation), unless specified otherwise.
Once switched to DTMF, dialling will remain in this mode until either a Recall (Flash) operation
or until the chip returns to the on-hook state.
Last Number Redial (LNR)
The function of the on-chip LNR store is to retain automatically a manually dialled number for
redialling later. The capacity of the memory is 24 digits. If a number is dialled which is longer
than this, dialling will continue, but redialling will not be allowed with this number. To redial
a number in the LNR store, the LNR key may be pressed once, or the Redial key can be
pressed twice.
The last number redial store has several features designed to assist the user:
Moving cursor facility
This facility is provided to aid use in PABX applications, where the user must first dial an
access digit, or digits, and then wait for a second dial tone before continuing dialling.
This allows a user to enter the first digit or digits of the number in the last number redial store
manually before pressing the LNR key; the remainder of the number will be dialled when
the LNR key is pressed.
If the digit(s) dialled manually do not match those in the LNR memory, then redialling will
be inhibited for the remainder of the call, and the numbers entered will be saved in the LNR
memory for redialling in a subsequent call.
If the user manually dials the first digit(s) in the LNR memory, and then goes on-hook, the
whole contents of the memory will be retained.
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