TDA7478
Fi
SINGLE CHIP RDS DEMODULATOR
1 FEATURES
■ VERY HIGH RDS DEMODULATION QUALITY
WITH IMPROVED DIGITAL SIGNAL
PROCESSING
■ HIGH PERFORMANCE, 57KHz BANDPASS
FILTER (8th ORDER)
■ FILTER ADJUSTMENT FREE AND WITHOUT
EXTERNAL COMPONENTS
■ PURELY DIGITAL RDS DEMODULATION
WITHOUT EXTERNAL COMPONENTS
■ RDS SIGNAL QUALITY OUTPUT
■ 4.332MHz CRYSTAL OSCILLATOR(8.664MHz
OPTIONAL)
■ LOW NOISE CMOS TECHNOLOGY
■ LOW RADIATION
2 DESCRIPTION
The TDA7478 recovers the additional inaudible RDS
information which is transmitted by FM radio broadcasting stations and operates in accordance with the
Figure 2. Block Diagram
gure 1. Packages
SO16
TSSOP16
Table 1. Order Codes
Part Number Package
TDA7478D SO16
E-TDA7478AD TSSOP16
EBU (European Broadcasting Union) specifications.
The device is made up of two sections: a cascaded
antialiasing + switched capacitors 8th bandpass filter
for precise RDS band selection and a demodulating
section that performs the extraction od RDS data
stream (RDDA) and clock (RDCL), to be further processed by a suitable RDS decoder.
Output for RDS signal quality is also present.
4.332MHz C2 47pFC1 27pF
MPX
270pF
FILOUT
V
S
100nF
10µF
November 2004
4
8
12
3VREF
GND
T57
15
2nd ORDER
ANTIALIASING
FILTER
8th ORDER
SC-BANDPASS
FILTER
-
+
6
BIPHASE DEC.
BIPHASE DEC.
57KHz PLL
POLARITY
INTEGRAL
OSCILLATOR &
DIVIDER
OSCOUTOSCIN
1413
5
OSEL
9
FSEL
16
1187.5Hz
PLL
QUAL DET.
0
MUX
EXTRES
DIFF. DECODER
TEST LOGIC
11
D03AU1490
1
RDCL
7
N.U.
1
QUAL
2
RDDA
10
TM
Rev. 2
1/8
TDA7478
Table 2. Pin Description
No pin Name Description
1 QUAL Output for signal quality indication (High = good)
2 RDDA RDS data output
3 VREF Reference voltage
4 MPX RDS input signal
5 OSEL Oscillator selector pin:
6 GND Ground
7 N.U. Not Used (to be left open)
8 FILOUT Filter output
9 FSEL Frequency selector pin:
10 TM Test mode pin: - open = normal operation - closed to VS = testmode
11 EXTRES Reset pin: - open=run mode - closed to VS = reset condition
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
S
- open, closed to V
- closed to GND=external driven
- open = 4.332MHz
- closed to VS = 8.664MHz
Supply voltage
= quartz oscillator
S
Figure 3. Pin Connection (Top view)
QUAL
RDDA
VREF
MPX
OSEL
GND
N.U.
1
2
3
4
5
6
7TM
15
14
13
12
11
10
RDCL16
T57
OSCOUT
OSCIN
V
S
EXTRES
FILOUT 8 FSEL9
D97AU752A
Table 3. Thermal Data
Symbol Description Value Unit
R
th j-case
Thermal Resistance Junction-case Max. 200 °C/W
2/8
TDA7478
Table 4. Absolute Maximum Ratings
Symbol Parameter Value Unit
V
S
T
op
T
stg
Table 5. Electrical Characteristcs
(T
= 25°C, VS = 5V, unless otherwise specified)
amb
Symbol Parameter Test Condition Min. Typ. Max. Unit
V
S
I
S
FILTER
f
C
BW 3dB Bandwidth 2.5 3 3.5 kHz
G Gain f = 57kHz 17 20 23 dB
A Attenuation ∆f ± 4kHz 22 dB
R
I
R
L
S/N Signal to noise ratio V
V
IN
S
RDS
S
ARI
V
REF
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
VIL Input voltage low
Output pins (RDCL, RDDA, QUAL, T57)
V
OH
V
OL
OSCILLATOR
CLL
V
VCLH Input level OSCIN pin OSEL = open circuit 4 V
V
PP
(1) The 3rd harmonic (57kHz) must be less than -40dB with respect to the input signal plus gain.
Supply Voltage -0.3 to 7 V
Operating Temperature Range -40 to 85 °C
Storage Temperature -55 to 150 °C
Supply voltage 4.5 5 5.5 V
Supply current 7.5 12.0 mA
Center frequency 56.6 57 57.4 kHz
f = 38kHz 60 dB
f = 67kHz 45 dB
Input impedance of MPX 120 KΩ
Load impedance on FILOUT 1 MΩ
= 3mVRMS 30 40 dB
IN
MPX input signal
f = 19kHz; T3 ≤ 40dB
f = 57kHz (RDS)
(1)
100050mV
mV
RDS Detection Sensitivity 1 mVrms
ARI Detection Sensitivity 3 mVrms
Reference VS/2 V
Input Current VIN = 5V (pull-down input) 15 30 µA
Input Current VIN = 0V (pull-up input) -25 -10 µA
Input voltage high
0.7 · VS0.8 · V
0.2 · VS0.3 · V
S
V
V
S
Ouput voltage high IL = 0.5mA 4 4.6 V
Output voltage low IL = 0.5mA 0.4 1 V
Input level OSCIN pin OSEL = open circuit 1 V
Amplitude OSCOUT OSEL = open circuit 4.5 V
Amplitude OSCIN
(for external drive)
OSEL = GND, f = 4.332MHz
OSEL = GND, f = 8.664MHz
100
120
mVpp
mVpp
RMS
RMS
3/8
TDA7478
Figure 4. RDS timing diagram
CLOCK
LINE
DATA
LINE
3 OUTPUT TIMING
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
µ
s after the clock transi-
tion.
4 OSCILLATOR CONTROLS (FSEL, OSEL)
Two 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 following table for reference:
Table 6.
Crystal FSEL (pin configuration)
4.332MHz
8.664MHz
connected to GND or open
connected to Vs
A special mode is introduced to reduce EMI. With pin OSEL connected to GND the internal oscillator is switched
off and an external sinusoidal frequency 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:
Table 7.
Crystal C1 C2
4.332MHz
8.664MHz
27pF
27pF
47pF
-
4/8
Figure 5. SO16 Mechanical Data & Package Dimensions
TDA7478
DIM.
A 2.35 2.65 0.093 0.104
A1 0.10 0.30 0.004 0.012
B 0.33 0.51 0.013 0.200
C 0.23 0.32 0.009 0.013
(1)
10.10 10.50 0.398 0.413
D
E 7.40 7.60 0.291 0.299
e 1.27 0.050
H 10.0 10.65 0.394 0.419
h 0.25 0.75 0.010 0.030
L 0.40 1.27 0.016 0.050
k 0˚ (min.), 8˚ (max.)
ddd 0.10 0.004
(1) “D” dimension does not include mold flash, protusions or gate
burrs. Mold flash, p rotusions or gate bur rs shall not exceed
0.15mm per side.
mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
OUTLINE AND
MECHANICAL DATA
SO16 (Wide)
0016021 C
5/8
TDA7478
Figure 6. TSSOP16 Mechanical Data & Package Dimensions
DIM.
A 1.200 0.047
A1 0.050 0.150 0.002 0.006
A2 0.800 1.000 1.050 0.031 0.039 0.041
b 0.190 0.300 0.007 0.012
c 0.090 0.200 0.005 0.009
D (1) 4.900 5.000 5.100 0.114 0.118 0.122
E 6.200 6.400 6.600 0.244 0.252 0.260
E1 (1) 4.300 4.400 4.500 0.170 0.173 0.177
e 0.650 0.026
L 0.450 0.600 0.750 0.018 0.024 0.030
L1 1.000 0.039
k 0˚ (min.) 8˚ (max.)
aaa 0.100 0.004
Note: 1. D and E1 does not include mold flash or protrusions.
mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
Mold flash or potrusions shall not exceed 0.15mm
(.006inch) per side.
OUTLINE AND
MECHANICAL DATA
TSSOP16
(Body 4.4mm)
6/8
0080338 (Jedec MO-153-AB)
Table 8. Revision History
Date Revision Description of Changes
July 2004 1 First Issue
November 2004 2 Add in the table 5 “RDS and ARI Detection Sensitivity” parameters.
TDA7478
7/8
TDA7478
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of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted
by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject
to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not
authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
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