E-TDA7331DTR - STMicroelectronics

VERY HIGH RDS DEMODULATION QUALITY

WITH IMPROVED DIGITAL SIGNAL PROC-

ESSING

HIGH PERFORMANCE, 57KHz BANDPASS

FILTER (8th ORDER)

PURELY DIGITAL RDS DEMODULATION

WITHOUT EXTERNAL COMPONENTS

ARI INDICATION AND RDS SIGNAL QUAL-

ITY OUTPUTS

4.332MHz CRYSTAL OSCILLATOR

(8.664 and 17.328MHz SELECTABLE OP-

TIONS)

LOW NOISE CMOS TECH NO LOG Y

LOW RA DIATION

DESCRIPTION

The TDA7331, an improved version of

TDA7330B, recovers the additional inaudible

RDS information which is tr ansmitted by FM radio

broadcasting stations and operates in accord-

ance with the EBU (European Broadcasting Un-

ion) specifications.

The device is made up of two sections: a cas-

caded antialiasing + switched capacitors band-

pass filter for precise RDS band selection and a

demodulating s ection that per forms the ex traction

od RDS data stream (RDDA) and clock (RDCL),

to be furher processed by a suitable RDS de-

coder.

Outputs for RDS signal quality and ARI indication

are also present.

September 2003

2nd ORDER

ANTIALIASING

FILTER

8th ORDER

SC-BANDPASS

FILTER

MPX 1

270pF

FILOUT

2VREF

100nF

10µF

OSCILLATOR &

DIVIDER

57KHz PLL

FAST ARI

INDICATOR

POLARITY

BIPHASE DEC.

INTEGRAL

BIPHASE DEC.

1187.5Hz

PLL

MUX

1DIFF. DECODER

TEST LOGIC

QUAL DET.

GND N.C.

6,7,8,17 20

EXTRES

910

D97AU686B

RDDA

QUAL

ARI

RDCL

FSEL

OSEL

OSCOUTOSCIN

4.332MHz C2 47pFC1 27pF

T57

BLOCK DIAGRAM and TEST CIRCUIT

TDA7331

SINGLE CHIP RDS DEMO DULATOR + FILTER

DIP20 SO20

ORDERING NUMBERS:

TDA7331 TDA7331D

1/7

MPX

VREF

OSEL

FILOUT

GND

N.C.

OSCOUT

9 RDCL

RDDA

QUAL

ARI

N.C.

FSEL

EXTRES20

D97AU687

OSCIN 10 T5711

PIN C ONNECTION

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

VSSupply Voltage 7 V

Top Operating Temperature Range -40 to 85 °C

Tstg Storage Temperature -55 to 150 °C

PIN FUNCTION

No pin Name Functional description

1 MPX RDS input signal

2 VREF Reference voltage

3 OSEL Oscillator selector pin: - open, or closed to Vs = quartz oscillator

- closed to GND = external driven

4 FILOUT Filter output

5 GND Ground

6 nc Not co nnected

7 nc Not co nnected

8 nc Not co nnected

9 OSCOUT Oscillator output

10 OSCIN Oscillator input

11 T57 Testing output pin: 57kHz clock output

12 RDCL RDS clock output 1187.5Hz

13 RDDA RDS data output

14 QUAL Output for signal quality indication (High = good)

15 ARI Output for ARI indication: - high when RDS+ARI are present

- high when only ARI is present

- low when only RDS is present

- undefined when nos signal is present

16 Vs Supply voltage

17 nc Not co nnected

18 FSEL Frequency selector pin: - 100K to VS = 17.328MHz

- open = 4.332MHz

- closed to VS = 8.664MHz

19 TM Test mode pin: - open = normal operation

- closed to VS = testmode

20 EXTRES Reset pin: - open = run mode

- closed to VS = reset condition

TDA7331

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THERMAL DATA

Symbol Description DIP20 SO20 Unit

Rth j-amb Thermal Resistance Junction-Ambient Max 100 200 °C/W

ELECTRICA L CHARACTERI STICS (T amb = 25°C, VS = 5V, unless otherwise specified).

Symbol Parameter Test Condition Min. Typ. Max. Unit

VSSupply voltage 4.5 5 5.5 V

ISSupply current 7.5 11.0 mA

FILTER

fCCenter frequency 56.5 57 57.5 kHz

BW 3dB Bandwidth 2.5 3 3.5 kHz

G Gain f = 57kHz 18 20 22 dB

A Attenuation ∆f ± 4kHz 18 22 dB

f = 38kHz 50 60 dB

f = 67kHz 35 45 dB

RIInput impedance of MPX 80 120 150 KΩ

RLLoad impedance on FILOUT 1 MΩ

S/N Signal to noise ratio VIN = 3mVRMS 30 40 dB

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

f = 57kHz (RDS+ ARI) 1000

50 mVRMS

mVRMS

VREF Reference VS/2 V

DEMODULATOR

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

Input pin (OSEL) with internal pull up resistor

IPD Input Current VIN = 5V (pull-down input) 15 30 µA

IPU Input Current VIN = 0V (pull-up input) -25 -10 µA

VIH Input voltage high 0.7 ⋅ VS0.8 ⋅ VSV

VIL Input voltage low 0.2 ⋅ VS0 .3 ⋅ VSV

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

VOH Ouput voltage high IL = 0.5mA 4 4.6 V

VOL 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

VPP Amplitude OSCIN

(for external drive) OSEL = GND,

f = 4.332MHz 100 mVpp

OSEL = GND,

f = 8.664MHz 120 mVpp

OSEL = GND,

f = 17.328MHz 150 mVpp

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

TDA7331

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OU TPU T TI M I N G

The RDS (1187.5Hz) output clock on RDCL line

is synchronized to the incoming data.

According to the internal PLL lock condition data

change can result on the falling or on the rising

clock edge. (see Fig. 1)

Whichever clock edge is used by the decoder

(rising or falling edge) the data will remain valid

for 416.7 µsec after the clock transition.

OSCILLATOR CONTROLS (FSEL, OSEL)

Three different crystal frequencies can be used.

The adaption of the internal clock divider to the

external crystal is achieved via the input pin

FSEL. See the followings table for reference:

Crystal FSEL (pin configuration)

4.332MHz

8.664MHz

17.328MHz

connected to GND or open

connected to Vs

external resistor of 100K to Vs

A special m ode is introduc ed to reduce EMI. Wit h

pin OSEL connected to GND the internal oscilla-

tor is switched off and an external sinusoidal fre-

quency could be applied on OSCIN. The peak to

peak voltage of this signal can be reduced down

to 60mV.

In this mode the frequency selection via FSEL is

still active.

Suggested values of C1 and C2 are shown in the

following table:

Crystal C1 C2

4.332MHz

8.664MHz

17.328MHz

27pF

47pF

Figure 1. RDS timing diagram

CLOCK

LINE

DATA

LINE

TDA7331

4/7

DIP20

DIM. mm inch

MIN. TYP. MAX. MIN. TYP. MAX.

a1 0.254 0.010

B 1.39 1.65 0.055 0.065

b 0.45 0.018

b1 0.25 0.010

D 25.4 1.000

E 8.5 0.335

e 2.54 0.100

e3 22.86 0.900

F 7.1 0.280

I 3.93 0.155

L 3.3 0.130

Z 1.34 0.053

OUTLINE AND

MECHANICAL DATA

TDA7331

5/7

110

1120

A1 C

SO20MEC

h x 45˚

SO20

DIM. mm inch

MIN. TYP. MAX. MIN. TYP. MAX.

A 2.35 2.65 0.093 0.104

A1 0.1 0.3 0.004 0.012

B 0.33 0.51 0.013 0.020

C 0.23 0.32 0.009 0.013

D 12.6 13 0.496 0.512

E 7.4 7.6 0.291 0.299

e 1.27 0.050

H 10 10.65 0.394 0.419

h 0.25 0.75 0.010 0.030

L 0.4 1.27 0.016 0.050

K 0˚ (min.)8˚ (max.)

OUTLINE AND

MECHANIC AL DATA

TDA7331

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