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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
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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)
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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
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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
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