SGS Thomson Microelectronics TS7514CP, TS7514CFN Datasheet

PROGRAMMABLE V.23 MODEM WITH DTMF

.

PROGRAMMABLEMODES :

- Modem75bps transmit, 1200bpsreceive

- Modem1200bps transmit, 75bpsreceive

- DTMFdialing

- Callstatus tone detection

- Auxiliary analog transmitinput

- Analog testloopback

.

PROGRAMMABLEFUNCTIONS :

- Transmissionlevel

- Hysteresisand detection level

- Filters(reception and transmission)

- Line monitoring and buzzer

- DTMFfrequencies

.

FIXEDCOMPROMISELINE EQUALIZER

.

AUTOMATICBIAS ADJUSTMENT

.

INTEGRATEDDUPLEXER

.

STANDARDLOWCOSTCRYSTAL(3.579MHz)

.

TAXTONE REJECTION

.

POWER-UPINITIALIZATION OF REGISTERS

.

OPERATESFROM

.

CMOS

±

5V

TS7514

DIP24

(Plastic Package)

PLCC28

(Plastic Leaded Chip Carrier Package)

ona 4-wireline. Itsprogrammingconceptmakesit
the ideal component to design low-cost intelligent
modems, featuring auto dialing and auto answer­ing. The TS7514 conforms to CCITT V.23 recom­mendation. The chip incorporates DTMF dialing,
linemonitoring, tone and dialing detection.

DESCRIPTION

The TS7514 is an FSK modem which can be
programmed for asynchronous half-duplex voice­bandcommunicationsona 2-wirelineorfullduplex

PIN CONNECTIONS

DIP24

MOD/DTMF

MC/BC

RTS
ENP

DGND

TxD

PRD

XTAL IN

XTAL OUT

DCD

RxD

ZCO

1
2
3
4
5
6
7
8
9
10
11
12

24

AXTL

23

WLO

22

ATO

21

V+

20

AGND

19

V-

18

RAO1

17

RAI1

16

RAI2

15

RAO2

14

RFO

13

RDI

ORDER CODES

Part Number Temperature Range Package

TS7514CP 0 to 70
TS7514CFN 0 to 70

PLCC28

RTS

MC/BC

4

321

5

ENP

6

DGND

7

TxD

8

PRD

9

N/C

XTAL IN

10
11

12131415161718

N/C

DCD

o

C DIP24

o

C PLCC28

N/C

MOD/DTMF

ATXL

WLO

ATO

282726

RDI

RxD

ZCO

RFO

RAO2

25

V+

24

AGND

23

V-

22

RAO1

21

RAI1

20

RAI2

19

N/CXTAL OUT

7514-01.TBL

7514-01.EPS /7514-02.EPS

November 1998

1/19

TS7514

PIN DESCRIPTION

Name

MOD/DMTF 1 1 MODEM or DMTF Operating Mode Selection.

MC/BC 2 3 Digital Control Input.

RTS 3 4 Request to Send.

ENP 4 5

DGND 5 6 Digital Ground = 0V. All digital signals are referenced to this pin.

TxD 6 7 Digital Input for Transmit or Control Data

PRD 7 8 Digital Input for ControlData. Selected through ENP

XtaIIN 8 10 Crystal Oscillator Input. Can be tied to an external clock generator.

XtaIOUT 9 11 Crystal Oscillator Output

DCD 10 13 DataCarrier Detect Output

RxD 11 14 Digital Receive Data Output

ZCO 12 15 Zero Crossing Rx Digital Output (ringing detection)

RDI 13 16 Analog Output for the Receive Signal after Filtering or Analog Input for the

RFO 14 17 Analog Receive Filter Output

RAO2 15 18 A2 Amplifier Output

RAI2 16 20 A2 Amplifier Inverting Input
RAI1 17 21 A1 Amplifier Inverting Input

RAO1 18 22 A1 Amplifier Output

V- 19 23 Negative Supply Voltage : – 5V ±5%

AGND 20 24 Analog Ground = 0 V. Reference Pin for AnalogSignals

V+ 21 25 Positive Supply Voltage : + 5V ±5%

ATO 22 26 Analog Transmit Output

WLO 23 27 Analog Output for Line Monitoring and Buzzer

ATxI 24 28 Direct Analog Input Transmit Filter

Pin Number

DIP24 PLCC28

Description

Also controls write operations to control registers (if MOD/DMTF = 0 and
MC/BC= 0).

In MODEM mode, it sets transmission mode to main or back channel. It also
permits selection of dialing or control registers programming.

When RTS = 0, the circuit sends an analog signal to the ATO output.The signal
depends on the operating mode selected.
When RTS = 1,the signal sent to ATOis suppressedafter its firstzerocrossing.
When MOD/DMTF = 0 and MC/BC = 0, the RTS pin acts as a clock for serial
data loading into the input register.

Serial Register Write Select Input. When ENP = 0, the serial register input is
connected to TxD. When ENP = 1, the register input is connected to PRD.

QUARTZ

= 3.579MHz.

f

Amplifier-limiter.

7514-02.TBL

2/19

Figure1 : SimplifiedBlock Diagram

TS7514

TxD

PRD

ENP

RTS

MC/BC

MOD/DTMF

DCD

TS7514

Tx DATA

MODE

CARRIER/TONE

LEVEL DETECTOR

CARRIER/TONE

FREQUENCY
GENERATOR

INPUT SHIFT

CONTROL

REGISTER

CONTROL

REGISTERS

ATxI

DMTF DATA

TO
PROGRAMMABLE
FUNCTIONS

Tx

FILTER

V+ DGND V- AGND

ATTENUATOR

ATTENUATORBUZZER

ATO

WLO

RxD

ZCO

RX

DATA

FSK

DEMODULATOR

Xtal OUT Xtal IN

G

MASTER

CLOCK

Rx

FILTER

CLOCK

GENERATOR

G

RDI RFO

DUPLEXER

RAI1
RAO1
RAI2
RAO2

7514-03.EPS

3/19

TS7514

FUNCTIONAL DESCRIPTION

The TS7514 circuit is an FSK modem for half-du­plex,voice-bandasynchronoustransmissions on a
2-wire line according to CCITT recommendation
V.23 or full duplexon 4 wire-line.

The circuit features DTMF dialing, call status tone
detection and line monitoring in both dialing and
automaticanswermodes. Asignallingfrequencyis
availableat the line monitoring output (buzzer).

Ring detection is possible by using the signal de­tection function and bypassing the receive filter.
Thereceive signal at ZCO outputcan befilteredin
the associated microprocessor.

TheTRANSMITchannel (Tx)includes :

- Twoprogrammablefrequencygenerators.

- Oneswitchedcapacitorfilter(SCF)withlow-pass
or bandpass configuration and its associated
propagationdelay corrector.

- Onecontinuous time low-passsmoothing filter.

- Oneattenuator,programmable from0 to + 13dB
by 1dB steps.

- Oneprogrammableanalog input.

TheRECEIVEchannel (Rx) includes:

- Two operational amplifiers for duplexer imple­mentation.

- Onecontinuous time low-passanti-aliasingfilter.

- Oneprogrammablegain amplifier.

- Onelinear compromiseequalizer.

- One switchedcapacitor band pass filter (can be
set to eithermain or back channel).

- Onecontinuous time low passsmoothing filter.

- Onelimiting amplifier.

- Onecorrelationdemodulator.

- Oneprogrammablelevel signal detector.

Figure2 :

InternalControl Register

RTS

The LINE MONITORINGchannelincludes:

- One buzzer.

- One 3-channelmultiplexer to selectbeetwen:

- Transmitchannel monitoring.

- Receivechannel monitoring.

- Buzzer.

- One programmableattenuator

Internal Control

Power-upInitialization

TheTS7514includespower-upinitializationof con­trol registers. This system sets the ATO transmis­sion output to an infinite attenuation position,
leaving time for the microprocessor to set up the
RPROG input on power up. Control registers are
also initialized when V+ is lower than 3V or V­greater than -3V.

Registers

WriteaccesstotheDTMFdataregisterandtoother
controlregistersis achievedinserialmodethrough
TxD input or PRD input. Addressing of these 4 bit
registersis indirect.They are accessedthroughan
8 bitshiftregisteraddressedwhenMOD/DTMF= 0
and MC/BC = 0. Data sent to the TxD input is
strobedon the RTS signal trailingedge.
Serial data is sent to the TxD input, with Least
Significant Bit (LSB) first. The 4 Most Significant
Bits (MSB) contain the control register address
while the4 LSB containassociated data.
Data transfer fromthe inputregister to the control
register(addressed bythe MSB’s)is startedby the
operating mode (MODEM or DTMF) selection
(MOD/DTMF= 1 or MC/BC= 1).

4/19

TxD or

PRD

Datas Addresses

CLK

8-BIT SHIFT REGISTER

(Input Register)

4-Bit Control

Register
RPROG

RDTMF

RATTE

RWLO

RPTF

RHDL

RPRX

RPROG

MOD/DTMF

MC/BC

RTS

TxD or PRD

D0 D1 D2 D3 D4 D5 D6 D7

Data Address

Time

7514-04.EPS

Figure3 : Detailed Block Diagram

TS7514

ATO

ATT

MX

MX RC

CORR

SCF

RATTE

RWLO

RPTF

4-bit Bus

RAI1

ATT

MX WLO

BUZZER

A1

Analog Loop

RAO1

RAI2

A2

RAO2

MX

RC

G

SCF

SCF

CORR

MX

5V 0V 0V -5V

Internal

Clocks

TIME

BASE

V+ AGND DGND V-

ATxL

Mode

TS7514

SCF

MX

FREQUENCY

GENERATOR

TxD

PRD

MX

ENP

RDTMF

Address

RTS

AND

DATA

REGISTER

SERIAL INPUT

MC/BC

Mode RPROG RHDL RPRX RPRF

Data

CONTROL

MOD/

DTMF

LEVEL

CARRIER

DETECTOR

DCD

Mode

RC

G

FSK

DEMODULATOR

RxD

ZCO

RDI RDO XTAL OUT XTAL IN

7514-05.EPS

5/19

TS7514

OPERATINGMODES

The various operating modes are defined by
MC/BCand MOD/DTMFinputs,andby thecontent
of a control register RPROG.
TheTS7514includes 8 controlregisters.Accessto
each control registeris achieved through an auxil­liary8-bit shiftregister(input register).The input of
that shift register is connected either to TxD or
PRD,dependinguponthe statusof theENPcontrol
pin (ie when ENP = 0 and ENP = 1 respectively).
Inbothcases,theRTSinputreceivesthe shiftclock
and sequentialy transfer is controlled by setting
simultaneouslyMOD/DTMF and MC/BC to 0. The

previous internal status and data are memorized
duringloadingof the inputregistersothattransmis­sion continues properly. That feature allows the
userto modifytransmissionlevelor linemonitoring
selection during transmission. The transmit chan­neloperatingmode(Modemmainor backchannel,
DTMF)canonly be modifiedwhenRTS =1. When
RTS = 0, the ATO transmit output is enabled and
thepreselectedoperatingmodeisactivated.When
RTSreturnsto 1, Modem or DTMF transmissionis
inhibited after the first zero crossing of the gener­ated signal.

MOD/DTMF MC/BC Transmission

1 1 MODEM, Main Channel MODEM, Back Channel
1 0 MODEM, Back Channel MODEM, Main Channel
0 1 DTMF DCD= Active Tone Detection (270 -500Hz) if RTS = 1…

0 0 If RTS = 0 when that configuration occurs, transmission and reception are not modified.

Note 1 :

The decision thresholdof the demodulatoroutput is shifted, so thatRxD changes from 0 to 1 at 1950Hz instead of 1700Hz.

If RTS = 1 (no signal sent on the line), transmission is not modified and reception is set
up to detect 2100Hz tone (note 1).

(ATO)

DCD = 1 if RTS = 0

Reception

(RxD, DCD)

MODEMTRANSMISSIONFREQUENCIES

Modulation

Rate

75bps 1

1200bps 1

TxD

0

0

CCITT R35 AND V.23

Recommendations (Hz)

390 ±2
450 ±2

1300 ±10
2100 ±10

Frequency Generated with

Xtal at 3.579MHz (Hz)

390.09

450.45

1299.76

2099.12

DTMF TRANSMISSIONFREQUENCIES

Specifications

DTMF (Hz)

f1
f2
f3
f4
f5
f6
f7
f8

697 ±1.8%
770 ±1.8%
852 ±1.8%

941 ±1.8%
1209 ±1.8%
1336 ±1.8%
1477 ±1.8%
1633 ±1.8%

Frequency Generated with

Xtal at 3.579MHz(Hz)

699.13

771.45

853.90

940.01

1209.31

1335.65

1479.15

1627.07

Dividing Ratio Error (%)

5120
4640
4192
3808
2960
2680
2420
2200

Error (Hz)

+0.09
+0.45

-0.24

-0.88

+0.31
+0.19
+0.22

-0.10

+0.03

-0.03
+0.15
+0.36

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