(4) The ON-HOOK and OFF-HOOK commands

These commands allows the DP pin to be controlled arbitrarily. The figure below shows the timing.

A hooking pause is inserted automatically when the OFF-HOOK command is input. The DP pin goes low when an

ON-HOOK command is input. During this low period, inputting pulse dial data will not cause the DP pin to return to

the high level. (Since the LSI performs a redial operation internally, the BUSYOUT pin will go high.) That is, the

low level is held until the next OFF-HOOK command is input.

(5) The redial command

The redial operation re-outputs the dial data in the LC73701M’s internal buffer memory. This buffer memory (redial

memory) can hold up to 32 digits of dialing data. This means that if 33 or more digits of dialing data are input, earlier

data will be overwritten starting with the thirty-third digit. After the following operations, the LC73701M will

perform a redial operation if a redial command is input.

1. When a flash command is input after dialing data has been input

2. When an STOP command is input after dialing data has been input

3. When an ON-HOOK command is input after dialing data has been input

4. When an OFF-HOOK command is input after dialing data has been input

(6) Mode settings

The break/make ratio (BMR) is switched between 33% and 39% by the BMR pin. The BMR pin is initialized after

power is first applied as shown in the table below.

No. 5561-10/11

LC73701M

Settings other than BMR (i.e. DPR, P/T, FLASH, PAUSE, and DPSEL) are switched using mode commands. The

information set by mode setting commands is stored internally by the LSI. Set the desired mode before inputting dial

data. When dial data is written to the buffer memory, the P/T register data is attached to that dial data.

(7) Output pins during dialing and the redial operation

See the table below. The terms ON and OFF in the table below refer to the on or off state of the n-channel open drain

output transistor.

Notes: *2 Turned off during dialing. However, since this command takes priority after an OFF-HOOK command is input, the on state is retained.

*1, 3: Turned off during dialing. However, since this command takes priority after a MUTE-ST command is input, the on state is retained.

*4: Since a hooking pause is inserted automatically, this output goes high during that operation.

BMR PIN

DPSEL

PAUSE

FLASH

P/T

DPR

H (33.3%)

(0) N-CH OD

(0) 4.0 s

(0) 707.0 ms

(1) Pulse

(1) 10 pps

L (39.2%)

(0) N-CH OD

(0) 4.0 s

(0) 707.0 ms

(0) Tone

(1) 10 pps

DP

MUTE1

MUTE, MUTE2

BUSYOUT

Redial memory

Power on

ON (L)

OFF

OFF

L

Readout is illegal

RES pin

ON (L)

*1 OFF

OFF

L

Readout is illegal

STOP command

*2 OFF (H)

*3 OFF

OFF

L

Readout allowed

ON-HOOK command

ON (L)

Retains the previous state

OFF

L

Readout allowed

OFF-HOOK command

OFF (H)

Retains the previous state

OFF

*4

H

Readout allowed

MUTE-ST command

Retains the previous state

ON

OFF

L

Readout allowed

MUTE-END command

Retains the previous state

OFF

OFF

L

Readout allowed