Samsung S1A0905-S0B0 User manual

RDS DEMODULATOR IC S1A0905
1
Preliminary
GENERAL DESCRIPTION
THE OUTLINE OF RDS(RADIO DATA SYSTEM)
Since 1988 most European national broadcaststations transmit RDS-
code beside their audio signals. RDS means Radio Data System and
was originally intended to give people in their cars additional informa-
tion about the weather or traffic(jams). But RDS has grown out to one
big channel of information. Radiostations send their name, the time
(with DCF-77 accuracy), their type of music (format) and even more.
The digital data of RDS are multiplexed into an FM radio wave using a
sub-carrier of 57kHz. The transmission rate of RDS data is
1.1875kbit/sec.
The transmission rate of RDS data is 1.1875kbit/sec, and RDS data
are encoded by differential encoding method. Then the encoded RDS data are modulated by BPSK using a clock
of 1.1875kHz. The modulated RDS data is are modulated by carrier suppressed amplitude modulation using a sub-
carrier of 57kHz. And that signal are multiplexed into an FM radio wave.
•RDS data are obtained by demodulating the received RDS modulation signal in RDS demodulator. First, the RDS
modulation signal is extracted from an FM radio wave using a band pass filter. The BPSK signal is obtained from
extracted RDS modulation signal by a 57kHz carrier recovery circuit. Then the bit rate clock of RDS data is
extracted from the BPSK signal, and the BPSK signal is demodulated using the extracted clock signal. Then the
RDS data are decoded by a differential decoding method using the demodulated BPSK signal.
FEATURES
•Low Current
•Two Stage Anti-aliasing Filter
•8'th 57kHz Switched Capacitor Bandpass Filter
•DSB Demodulation (Carrier Recovery)
•Clock Recovery Circuit
•Biphase Decoder & Differential Decoder
•Quality Indication Output for Demodulated Data
ORDERING INFORMATION
DEVICE PACKAGE OPERATING TEMP.
S1A0905-S0B0 16-SOP-225 -40 −+85
16−SOP−225

S1A0905 RDS DEMODULATOR IC
2
Preliminary
DESCRIPTIONS
The S1A0905 is a RDS demodulator. It recovers the RDS data which is transmitted by FM radio broadcasting. The
device operates in accordance with the EBU(European Broadcasting Union) specifications.
The IC includes a two stage antialiasing filter, a 57kHz switched capacitor bandpass filter, a comparator, a 57kHz
carrier recovery circuit, a bit rate clock recovery circuit, BPSK decoder, differential decoding circuit, and RDS signal
quality output.
BLOCK DIAGRAM
Smoothing filter & Comparator BPSK
BPSK Recovered clock
RDS DEMODULATOR
MUX
VREF
VDDA
VSSA
COMP QUAL(High or Low)
DATAO
CLKO
XOSCO
XOSCI
4.332MHz 20pF
20pF
2'nd Antialiasing Filter Switched capacitor filter
VSS
+5.0VVDD
RSTB
TEST
TIN
BIAS
8'th order
SCF
BGR
Oscillator &
Divider
Carrier
Recovery Clock
Recovery
PLL
1.1875kHz
Biphase
Decoder Differential
Decoder

RDS DEMODULATOR IC S1A0905
3
Preliminary
PIN CONFIGURATION
PIN DESCRIPTIONS
I: Input pin, O: Output pin, P: Power pin
Pin Name I/O Description
1QUAL OOutput for data quality indication (High = good data Low = bad data)
2DATAO ORDS data output
3VREF OSystem reference voltage output (2.5V)
4MUX IComposite signal input
5VDDA PAnalog power (+5.0V)
6VSSA P
7SGND PSystem ground
8COMP OBandpass filter output
9TEST ITest enable selecton pin (High = Test mode, Low = Normal mode)
10 TIN IInput signal for Test mode (Normally ground or open)
11 VSS PDigital power(+5.0V)
12 VDD P
13 XOSCI IXtal oscillator input
14 XOSCO OXtal oscillator output
15 RSTB IInput for system reset (High = active mode, Low = reset mode)
16 CLKO ORDS clock output (1187.5Hz)
QUAL
DATAO
VREF
MUX
VDDA
VSSA
SGND
COMP
SEC
S1A0905X01
TEST
TIN
VSS
VDD
XOSCI
XOSCO
RSTB
CLKO
16 SOP
(TOP VIEW)
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9

S1A0905 RDS DEMODULATOR IC
4
Preliminary
ELECTRICAL CHARACTERISTICS
Recommended Operating Conditions (Ta = 25 ° C)
Electrical Characteristics (VDDA = 5.0V, Ta = 25 ° C, fosc = 4.332MHz)
|
Parameter Symbol Min. Typ. Max. Unit Conditions
Power supply voltage1 VDDA 4.5 5.0 5.5 VAnalog power
Power supply voltage2 VDD 4.5 5.0 5.5 VDigital power
Parameter Symbol Min. Typ. Max. Unit Conditions
Operating current Isum -3.5 4.0 mA i(VDDA)+i(VDD)
Reference voltage VREF 2.4 2.5 2.6 V
Ouput high level Voh VDDA-1.0 VDDA-0.3 -VCLKO,DATAO,QUAL
Output low level Vol -0.2 1.0 VCLKO,DATAO,QUAL
<Filter block>
Center frequency Fc 56.5 57 57.5 kHz
Gain GA 23 26 29 dB Fc=57kHz, MUXFILO
Attenuation1 ATT1 -18 -22 -dB 57.0kHz4kHz
Attenuation2 ATT2 -65 -80 -dB 38kHz
Attenuation3 ATT3 -35 -50 -dB 67kHz
S/N ratio SN 30 40 -dB 57kHz Vin=3mVrms
Input level Vin 1-500 mVrms
<Demodulator block>
RDS detecter sensitivity SRDS -0.5 1.0 mVrms
RDS input level VRDS - - 300 mVrms
DATA rate DRATE -1187.5 -Hz
Clock transient vs. DATA CT -4.3 -us
Lockup time(RDS) TL -100 200 ms
<Oscillator block>
XTAL frequency Fosc -4.332 -MHz
Clock input high level Xosci 4.0 - - V
Clock input low level Xosco - - 1.0 V
Output Amplitude Xosc -4.5 -Vpp
Load capacitance CL -20 -pF

RDS DEMODULATOR IC S1A0905
5
Preliminary
TEST APPLICATION
Analog ground
Analog power Digital power
Digital ground
:Input & Monitor Pin
:Switch
:Crystal oscillator
S1A0905X01
4.332MHz
O1
5V
I2 SW2
O6
5V
QUAL DATAO VREF MUX VDDA VSSA SGND COMP
TESTTINVSSVDDXOSCIXOSCORSTBCLKO
20pF
20pF
I3
O7
AB
SW3
A B
SW4
SW5
16 15 14 13 12 11 10
9
1 2 3 4 5 6 7 8
A
B
A
B
O2 O3
O4
0.01uF
10uF
I1
10nF SW1
O5
5V
14pF
0.1uF 10uF 0.1uF 10uF
AB
A
B
*1: Digital power supply and Analog power supply are separated in the IC
*2: It must have VDD (Digital power supply) of a sufficiently low impedence

S1A0905 RDS DEMODULATOR IC
6
Preliminary
NOTES