STMicroelectronics TDA7479, TDA7479D Schematic [ru]

SINGLE CHIP RDS DEMODULATOR + FILTER

VERYHIGH RDS DEMODULATION QUALITY
WITH IMPROVED DIGITAL SIGNAL PROC­ESSING

HIGH PERFORMANCE, 57KHz BANDPASS
FILTER (8th ORDER)

FILTER ADJUSTMENT FREE AND WITHOUT
EXTERNALCOMPONENTS

PURELY DIGITAL RDS DEMODULATION
WITHOUTEXTERNAL COMPONENTS

ARI (SK INDICATION) AND RDS SIGNAL
QUALITYOUTPUT

4.332MHzCRYSTALOSCILLATOR
(8.664 and 17.328MHzOPTIONAL)

LOW NOISE CMOS TECHNOLOGY
LOW RADIATION

DESCRIPTION

The TDA7479 recovers the additional inaudible
RDS informationwhich is transmittedby FM radio
broadcasting stations and operates in accord­ance with the EBU (European Broadcasting Un­ion) specifications.

BLOCK DIAGRAM AND TESTCIRCUIT

TDA7479

DIP16 SO16

ORDERING NUMBERS:

TDA7479 TDA7479D

The device is made up of two sections: a cas­caded antialiasing + switched capacitors band­pass filter for precise RDS band selection and a
demodulatingsection that performs the extraction
od RDS data stream (RDDA) and clock (RDCL),
to be furher processed by a suitable RDS de­coder.

Outputs for RDS signal quality and ARI indication
are also present.

MPX

270pF

V

S

100nF

10µF

February 1998

FILOUT

4

8

12

3VREF

GND

4.332MHz C2 47pFC1 27pF

T57

15

2nd

ORDER

ANTIALIASING

FILTER

8th

ORDER

SC-BANDPASS

FILTER

INDICATOR

-

+

6

BIPHASE DEC.

BIPHASE DEC.

57KHz PLL

FAST

ARI

POLARITY

INTEGRAL

OSCILLATOR &

DIVIDER

OSCOUTOSCIN
1413

5

OSEL

9

FSEL

16

1187.5Hz
PLL

QUAL DET.

0

MUX

EXTRES

DIFF. DECODER

TEST LOGIC

11

D97AU751A

1

RDCL

7

ARI

1

QUAL

2

RDDA

10

TM

1/7

TDA7479

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

S

T

op

T

stg

THERMAL DATA

Symbol Description DIP16 SO16 Unit

R

th j-case

PIN DESCRIPTION

Nopin Name Description

1 QUAL Output for signal quality indication (High = good)
2 RDDA RDS data output
3 VREF Reference voltage
4 MPX RDS inputsignal
5 OSEL Oscillator selector pin: - open, closed to V

6 GND Ground
7 ARI Output for ARI indication: - high when RDS+ARI are present

8 FILOUT Filter output
9 FSEL Frequency selector pin: -100K to V

10 TM Test mode pin: - open = normal operation

11 EXTRES Reset pin: -open=run mode

12 V
13 OSCIN Oscillator input
14 OSCOUT Oscillator output
15 T57 Testing output pin: 57kHz clock output
16 RDCL RDS clock output 1187.5Hz

Supply Voltage -0.3 to 7 V
Operating Temperature Range -40 to 85
Storage Temperature -55 to 150

Thermal Resistance Junction-case Max. 100 200

= quartz oscillator

- closed to GND=external driven

- high when only ARI is present

- low when onlyRDS is present

- undefined when nos signal is present

- open = 4.332MHz

- closed to V

- closed to V

- closed to V

S

Supply voltage

S

S

= 17.328MHz

= 8.664MHz

S

= testmode

S

= reset condition

S

°
°

C/W

°

C
C

PIN CONNECTION(Top View)

2/7

QUAL

RDDA

VREF

MPX

OSEL

GND

ARI

1
2
3
4
5
6
7TM

15
14
13
12
11
10

FILOUT 8 FSEL9

D97AU752

RDCL16
T57
OSCOUT
OSCIN
V

S

EXTRES

TDA7479

THERMAL DATA

Symbol Description DIP20 SO20 Unit

R

th j-amb

Thermal Resistance Junction-Ambient Max 100 200

C/W

°

ELECTRICALCHARACTERISTICS(T

=25°C, VS=5V, unlessotherwisespecified).

amb

Symbol Parameter Test Condition Min. Typ. Max. Unit

V

S

I

S

Supply voltage 4.5 5 5.5 V
Supply current 7.5 11.0 mA

FILTER

f

C

BW 3dB Bandwidth 2.5 3 3.5 kHz

G Gain f = 57kHz 18 20 22 dB

A Attenuation

R

R

L

S/N Signal to noise ratio V

V

IN

V

REF

Center frequency 56.5 57 57.5 kHz

4kHz 18 22 dB

∆f±

f = 38kHz 50 60 dB
f = 67kHz 35 45 dB

Input impedance of MPX 80 120 150 K

I

Load impedance on FILOUT 1 M

=3mV

IN

RMS

30 40 dB

MPX input signal f = 19kHz; T3 ≤ 40dB(1)

f = 57kHz (RDS+ ARI)

Reference VS/2 V

100050mV

mV

DEMODULATOR

Input pins (EXTRES, FSEL, TM) all with internal pull down resistor
Input pin (OSEL) with internal pull up resistor

I

PD

I

PU

V

IH

V

IL

Input Current VIN= 5V (pull-down input) 15 30
Input Current VIN= 0V (pull-up input) -25 -10
Input voltage high 0.7⋅VS0.8⋅V

S

Input voltage low 0.2 ⋅ VS0.3⋅ V

S

Output pins (RDCL, RDDA, ARI, QUAL, T57)

V

OH

V

OL

Ouput voltage high IL= 0.5mA 4 4.6 V
Output voltage low IL= 0.5mA 0.4 1 V

OSCILLATOR

VCLL Input level OSCIN pin OSEL = open circuit 1 V

VCLH Input level OSCIN pin OSEL = open circuit 4 V

Amplitude OSCOUT OSEL= open circuit 4.5 V

V

PP

Amplitude OSCIN
(for external drive)

(1) The 3rd harmonic (57kHz) must be less than -40dB with respect to the input signalplus gain.

OSEL = GND,
f = 4.332MHz

OSEL = GND,
f = 8.664MHz

OSEL = GND,
f = 17.328MHz

100 mVpp

120 mVpp

150 mVpp

µ
µ

Ω

Ω

RMS
RMS

A

A
V
V

3/7