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
-
+
4
FILOUT
16
V
S
2VREF
100nF
10µF
OSCILLATOR &
DIVIDER
57KHz PLL
FAST ARI
INDICATOR
POLARITY
BIPHASE DEC.
INTEGRAL
BIPHASE DEC.
1187.5Hz
PLL
MUX
0
1DIFF. DECODER
TEST LOGIC
QUAL DET.
5
GND N.C.
6,7,8,17 20
EXTRES
910
3
18
12
15
14
D97AU686B
TM
19
RDDA
13
QUAL
ARI
RDCL
FSEL
OSEL
OSCOUTOSCIN
4.332MHz C2 47pFC1 27pF
11
T57
BLOCK DIAGRAM and TEST CIRCUIT
TDA7331
SINGLE CHIP RDS DEMO DULATOR + FILTER
DIP20 SO20
ORDERING NUMBERS:
TDA7331 TDA7331D
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MPX
VREF
OSEL
FILOUT
GND
N.C.
N.C.
N.C.
OSCOUT
1
3
2
4
5
6
7
8
9 RDCL
RDDA
QUAL
V
S
ARI
N.C.
FSEL
TM
EXTRES20
19
18
17
16
14
15
13
12
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
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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.
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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
27pF
27pF
47pF
-
-
Figure 1. RDS timing diagram
CLOCK
LINE
DATA
LINE
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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
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110
1120
A
e
B
D
E
L
KH
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
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