PCD3310AP datasheet(8/28 Pages) PHILIPS

8 / 28 page

1996 Nov 21

Philips Semiconductors

Product speciﬁcation

Pulse and DTMF diallers with redial

PCD3310; PCD3310A

If the CE input is taken to a LOW level for longer than time

period trd (see Figs 11 and 12 and Chapter 12) an internal

reset pulse will be generated at the end of the trd period.

The system changes to the static standby state. Short CE

pulses of < trd will not affect the operation of the device and

reset pulses are not produced.

7.4

Mode selection (PD/DTMF)

7.4.1

PULSE MODE

If PD/DTMF = VSS the pulse mode is selected. Entries of

non-numeric keys are neglected, they are neither stored in

the redial register nor transmitted.

7.4.2

DTMF MODE

If PD/DTMF = VDD the dual tone multi-frequency dialling

mode is selected. Each non-function key activated

corresponds to a combination of two tones, one of four

LOW and one of four HIGH frequencies, corresponding to

the key’s row and column in the keyboard matrix.

See Fig.4 and Table 3. The frequencies are transmitted

with a constant amplitude, regardless of power supply

variations. Harmonic content is filtered out thus meeting

the CEPT recommendations.

The transmission time is calibrated for redial. In manual

operation the duration of bursts and pauses is the actual

key depression time, but not less than the minimum

transmission time (tt) or minimum pause time (tp).

7.4.3

MIXED MODE

When the PD/DTMF pin is open-circuit the mixed mode is

selected. After activation of CE or FL (Flash) the device

starts as a pulse dialler and remains in this state until a

non-numeric dial key (A, B, C, D,

∗, #) or the function key >

is activated. Pressing a non-numeric dial key causes the

corresponding DTMF tones to be output, and any

subsequent dialling to be in DTMF mode. Pressing >

causes no output tones, but any subsequent dialling is in

DTMF mode. The > key should be used if the first DTMF

output required is numeric. The device remains in DTMF

dial mode until FL is activated or after a static standby

condition when CE is re-activated.

A connection between the PD/DTMF pin and VDD also

initiates DTMF dialling. Chip enable, FL or a connection of

PD/DTMF pin to VSS sets the device back to pulse dialling.

7.5

Keyboard inputs/outputs

The sense column inputs COL 1 to COL 4 and the

scanning row outputs ROW 1 to ROW 5 of the device are

connected to the keyboard as shown in Fig.4. All keyboard

entries are debounced on both the leading and trailing

edges for approximately time period te as shown in

Figs 11, 12, 13 and 14. Each entry is tested for validity.

When a key is depressed, keyboard scanning starts and

only returns to the sense mode after release of that key.

ROW 5 of the keyboard contains the following function

keys:

• P = memory clear and programming (notepad)

• FL = flash or register recall

• R = redial

• > = change of dial mode from pulse to DTMF in mixed

dialling mode.

In the pulse dialling mode the valid keys are the

10 numeric dial keys (0 to 9). The non-numeric dial keys

(A, B, C, D,

∗, #) have no effect on the dialling or the redial

storage. Valid function keys are P, R and FL.

In the DTMF mode all dial keys are valid. They are

transmitted as a dual tone combination and at the same

time stored in the redial register. Valid function keys are P,

FL and R.

In the mixed mode all key entries are valid and executed

accordingly.

Fig.4 Keyboard organization.

handbook, halfpage

MGE491

123

∗

ROWS

COLUMNS

KEYBOARD

54321

1234

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