MK53761 Datasheet, PDF (6/11 Pages) STMicroelectronics – REPERTORY DIALER

MK53761
DEVICE OPERATION
When the MK53761 is not actively dialing, it con-
sumes very little current. Row and Column inputs
assume opposite states off-hook. The circuit verifies
that a valid key has been entered by alternately
scanning the Row and Column inputs. If the input is
still valid following 32 ms of debounce, the digit is
stored into memory, and dialing begins after a pre-
signal delay of approximately 40 ms (measured
from initial key closure). Output tone duration is
shown in Table 1.
The MK53761 allows manual dialing of an indefinite
numberof digits, but if more than18 digits are dialed
per number, the 53761 will ”wrap around”. That is,
the extra digits beyond 18 will be stored at the be-
ginning of the LND buffer, and the first 18 digits will
no longer be available for redial. During autodial
fromLND or any memory location,key inputsare not
accepted, but they will suspend dialing until re-
leased.
NORMAL DIALING (off-hook)
D
D
D
...ETC
Normal dialing is straightforward, all keyboard en-
tries will be stored in the buffer and signaled in suc-
cession.
LAST NUMBER DIALED (LND)
LND
Last number dialing is accomplished by enteringthe
LND key.
HOOK FLASH
Flash consists of a timed Break of 560 ms. The
FLASH function is stored in memory, but it will not
be redialed as such. When a FLASH key is pressed,
no further key inputs will be accepted until the hook-
flash function (560 ms break) has been dialed. The
key input following a FLASH will be stored as the in-
itial digit of a new number (overwriting the number
dialed prior to the FLASH) unless it is another
FLASH. Consecutive FLASH entries after a number
is dialed will be stored sequentiallyin the LND mem-
ory and a subsequentLND entrywill cause the redial
of that number with a delay, but not hookflash
breaks, at the end of the redialing sequence. When
redialing in tone mode, MUTE OUTPUT will remain
active during the flash delay period.
SOFTSWITCH
Whendialing in the pulse mode, a softswitch feature
will allow a change to the tone mode whenever the
* key is depressed. Subsequent * key inputs will
cause the DTMF code for an * to be dialed. The soft-
switch will only switch from pulse to tone. After re-
turning to on-hook and back to off-hook, the part will
be in pulse mode. Redial by the LND key will repeat
the softswitch.
PROGRAMMING AND REPERTORY DIALING
Programming is independent of HKS (pin 17) and
MODE (pin 2).
To program, enter the following :
PROG, Digit 1, Digit 2, ..., MEM, Location (1-9).
When programming, dialing in inhibited.
To dail a numberfrom repertory memory (HKS must
be low) enter the following :
MEM, Location (1-9).
To save the last number dialed : PROG, MEM, Lo-
cation (1-9).
D
FLASH
D
...ETC
Hook flash may be entered into the dialed sequence
at any point by keying in the function key, FLASH.
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