SA589 FAMILY

sames

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Fig. 3 Earth loop recall

Dialling from memories

The SA589 must be 'off-hook' and idle:

1.

Press the appropriate memory key (S00 - S19). Dialling will now start.

2.

If dialling halts due to a Pause or an LD to DTMF changeover in the memory, the PAUSE

OUT pin will go high (logic '1'). Further dialling can be resumed by pressing the PAUSE/

CONT key or alternatively, by pulling the Column 4 pin low (for a minimum of 14 ms)

to achieve the same result thus allowing an external timer circuit to be used. The

PAUSE OUT output is reset when dialling resumes.

All keypad positions are disabled whilst memory dialling is in progress.

Timed Break & Earth Loop Recall

The SA589 supports both TBR and ELR and offers a common operating protocol in both

cases.

After a recall (Flash) operation, the dialling mode selected via the SELECT pin will be restored.

output goes low in order to produce the line break. When in DTMF mode, the MF OUT output

also goes low for the duration of the break.

ELR is supported via the column 3 pin. If this pin is connected to ground for a minimum of 20ms

during an ELR operation, the chip will offer the same operating protocol as for TBR.

This may be achieved by use of the circuit shown below in Fig. 3, or by use of a double contact

switch.

(1)

Other options are available.

(2)

Other TBR (Flash) periods are available as mask options

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DR-00685

SA589

COL 3

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