MC145446A Ver la hoja de datos (PDF) - Motorola => Freescale

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MC145446A

Single-Chip 300-Baud Modem with DTMF Transceiver

Motorola => Freescale 

Table 1. Function Mode Truth Table

M3 M2 M1 M0

Function Mode

0 0 0 0 FSK

0 0 0 1 FSK Analog Loopback

0 0 1 0 CPTD

0 0 1 1 Answer Tone

0 1 0 0 DTMF Transmit

0 1 0 1 Single Tone

0 1 1 0 Power–Down 1

0 1 1 1 Power–Down 2

1 0 0 0 DTMF Receive

1 0 0 1 DTMF Analog Loopback

FSK Mode

The transmitter and the receiver work as an FSK modu-

lator/demodulator. The SD pin goes low when a valid FSK

signal is detected.

DTMF Transmit Mode

The transmitter works as a DTMF tone generator. The

receiver is disabled.

CPTD (Call Progress Tone Detect) Mode

The receiver works as a 400 Hz call progress tone detec-

tor. The CD pin goes low when a valid call progress tone is

detected.

Answer Tone Mode

The transmitter works as a 2100 Hz answer tone genera-

tor. The receiver is disabled.

FSK Analog Loopback Mode

The transmitter, working as the FSK modulator, is internal-

ly connected to the receiver working as the FSK demodula-

tor. This feature is used for the device self test.

DTMF Receive Mode

The receiver works as a DTMF tone receiver. The DV goes

low when a valid DTMF tone is detected. The transmitter is

disabled.

DTMF Analog Loopback Mode

The transmitter, working as a DTMF tone generator, is in-

ternally connected to the receiver working as DTMF tone re-

ceiver. The DV goes low when the receiver detects a valid

DTMF tone. This feature is used for the device self test.

Single Tone Mode

The transmitter generates one of the eight frequencies of

the DTMF tone. The receiver is disabled.

Power–Down Mode 1

Whole internal circuits, except the oscillator, are disabled

and all outputs except the X1 pin go to the high–impedance

state. The supply current decreases to 500 µA (max).

Power–Down Mode 2

Whole internal circuits, including the oscillator, are dis-

abled and all outputs go to the high–impedance state. The

supply current decreases to 1.0 µA (max).

Transmit Attenuator/AGC Gain Set (A3 to A0)

Four–bit serial data (A3 – A0) sets up the analog transmit

level in the FSK, answer tone, DTMF, analog loopback, and

single tone mode. The range of the transmit attenuator is 0 to

15 dB in 1 dB steps. The attenuator, however, does not affect

the external signal input from the DSI. These bits also deter-

mine the AGC amplifier gain in the DTMF receive mode. In

normal operation, “Automatic” may be selected so that the

gain is automatically adjusted corresponding to the input sig-

nal level. See Table 3 for a detailed description.

Transmit Tone Frequency (T3 to T0)

These four bits (T3 to T0) determine the DTMF tone fre-

quencies in DTMF transmit and DTMF analog loopback

mode, and determine the single tone frequency in the single

tone mode. Tone frequency assignments with reference to

T3 – T0 are shown in Table 4.

Function Mode

FSK

FSK Loopback

Call Progress Tone

Answer Tone

DTMF Transmit

Single Tone

Power–Down 1, 2

DTMF Receive

DTMF Loopback

Table 2. Output Status

Output Pin

RxD

SD/CD/DV

Receive

Digital Data

Carrier

Detect Signal

TxA1, TxA2

FSK

H

H

H

H

High Impedance

H

CPTD Signal

H

H

H

High Impedance

DV Signal

VCC/2

Answer Tone

DTMF Tone

Single Tone

High Impedance

VCC/2

DTMF Tone

MC145446A

10

MOTOROLA

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