Philips SAA6581T Datasheet

INTEGRATED CIRCUITS

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SAA6581T

RDS/RBDS demodulator

Product speciﬁcation File under Integrated Circuits, IC01

2001 May 07

Philips Semiconductors Product speciﬁcation

RDS/RBDS demodulator SAA6581T

FEATURES

• Integrated switched capacitor filter

• Demodulates European Radio Data System (RDS) or

the USA Radio Broadcast Data System (RBDS) signals

• Oscillator frequencies: 4.332 or 8.664 MHz

• Integrated ARI clamping

• CMOS device

• Single supply voltage: 5 V

• Extended temperature range: −40 to +85 °C

• Low number of external components.

GENERAL DESCRIPTION

The RDS/RBDS demodulator is a CMOS device with integrated filtering and demodulating of RDS/RBDS signals comingfrom a multiplexed input data stream. Data signal RDDA and clock signal RDCL are provided as outputs for further processing by a suitable microcomputer, for example CCR921 and CCR922.

The SAA6581T replaces SAA6579 in function and pin-compatibility.

APPLICATIONS

The RDS/RBDS system offers a large range of applications from the many functions that can be implemented. For car radios the most important are:

• Program Service (PS) name

• Traffic Program (TP) identification

• Traffic Announcement (TA) signal

• Alternative Frequency (AF) list

• Program Identification (PI)

• Enhanced Other Networks (EON) information.

QUICK REFERENCE DATA

SYMBOL PARAMETER MIN. TYP. MAX. UNIT

DDA

DDD

DD(tot)

i(MPX)

i(xtal)

analog supply voltage 4.0 5.0 5.5 V digital supply voltage 4.0 5.0 5.5 V total supply current − 6.0 − mA RDS input sensitivity at pin MPX 1 −−mV crystal input frequency − 4.332 − MHz

− 8.664 − MHz

ORDERING INFORMATION

TYPE

NUMBER

NAME DESCRIPTION VERSION

PACKAGE

SAA6581T SO16 plastic small outline package; 16 leads; body width 7.5 mm SOT162-1

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Philips Semiconductors Product speciﬁcation

RDS/RBDS demodulator SAA6581T

BLOCK DIAGRAM

handbook, full pagewidth

multiplex

input

+5 V

100 nF

330 pF

MPX

DDA

8th ORDER

BANDPASS FILTER

POWER SUPPLY

AND RESET

6 V

SSAVref

57 kHz

560 pF

SAA6581T

TEST

CONTROL

TCON

2.2 µF

Fig.1 Block diagram.

CINSCOUT

CLOCKED

COMPARATOR

MODE

47 pF

OSCILLATOR

AND CLOCK

13 14

OSCIQ1OSCO

+5 V

DDD

RDS/RBDS

DEMODULATOR

SIGNAL QUALITY

DETECTOR

C5 56 pF

113 V

SSD

C7 100 nF

SYNC

RDCL

RDDA

QUAL

MHB899

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Philips Semiconductors Product speciﬁcation

RDS/RBDS demodulator SAA6581T

PINNING

SYMBOL PIN DESCRIPTION

QUAL 1 signal quality indication output RDDA 2 RDS data output V

ref

3 reference voltage output (1/2V MPX 4 multiplex signal input V V

DDA SSA

5 analog supply voltage (5 V)

6 analog ground (0 V) CIN 7 comparator input SCOUT 8 switched capacitor ﬁlter output MODE 9 oscillator frequency select input SYNC 10 ARI clamping control input V V

SSD DDD

11 digital ground (0 V)

12 digital supply voltage (5 V) OSCI 13 oscillator input OSCO 14 oscillator output TCON 15 test control input RDCL 16 RDS clock output

DDA

)

handbook, halfpage

QUAL

RDDA

ref

MPX

DDA

SSA

CIN

SCOUT

SAA6581T

5 6 7 8

MHB900

Fig.2 Pin configuration.

16 15 14 13 12 11 10

RDCL TCON OSCO OSCI V

DDD

SSD

SYNC MODE

FUNCTIONAL DESCRIPTION RDS/RBDS signal demodulation

BANDPASS FILTER The bandpass filter has a centre frequency of 57 kHz. It

selects the RDS/RBDSsub-band fromthe multiplex signal MPX and suppresses the audio signal components. The filter block contains an analog anti-aliasing filter at the inputfollowedby an 8thorderswitched capacitor bandpass filter and a reconstruction filter at the output.

CLOCKED COMPARATOR Thecomparator digitizestheoutput signalfromthe 57 kHz

bandpass filter for further processing by the digital RDS/RBDS demodulator. To attain high sensitivity and to avoid phase distortion, the comparator input stage has automatic offset compensation.

DEMODULATOR The demodulator provides all functions of the SAA6579

and improves performance under weak signal conditions.

Demodulator functions include:

• 57 kHz carrier regeneration from the two sidebands (Costas loop)

• Symbol integration over one RDS clock period

• Bi-phase symbol decoding

• Differential decoding

• Synchronization of RDS/RBDS output data.

The RDS/RBDS demodulator recovers and regenerates the continuously transmitted RDS/RBDS data stream in the MPX signal and provides clock RDCL for the output signalsand dataoutput RDDA forfurther processingby an RDS/RBDS decoder, for example CCR921 or CCR922.

ARI CLAMP The demodulator checks the input signal for presence of

RDS only, or RDS plus ARI transmissions. After a fixed test period, if the SYNC inputis setHIGH the demodulator locksin the ‘verified’condition(seeTable 1). If SYNCisset LOW, the ARI clamping is reset (disabled). After SYNC returns to HIGH, the demodulator resumes checking the input signal.

2001 May 07 4

Philips Semiconductors Product speciﬁcation

RDS/RBDS demodulator SAA6581T

Table 1 Control pin SYNC

SYNC ARI CLAMPING

LOW internal ARI clamping disabled

HIGH ARI clamping allowed to be logged

SIGNAL QUALITY DETECTION Output QUAL indicates thesafety ofthe regeneratedRDS

Table 2 Control pins TCON and MODE

TCON MODE OSCILLATOR FREQUENCY

HIGH LOW 4.332 MHz HIGH HIGH 8.664 MHz

The clock generator generates the internal 4.332 MHz system clock and timing signal derivatives.

data (HIGH = ‘good’ data; LOW = ‘unsafe’ data).

Power supply and internal reset

Oscillator and system clock generator

For good performance of the bandpass and demodulator stages, the demodulator requires a crystal oscillator with a frequency of 4.332 or 8.664 MHz. The demodulator can operatewith eitherfrequency(see Table 2),so that aradio set with a microcontroller can run, in this case, with one crystal only. The demodulator oscillator can drive the

Thedemodulator hasseparate power supplyinputs forthe digital and analog parts of the device. For the analog functions an additional reference voltage (1⁄2V

DDA

) is internally generated and available via the output pin V The demodulator requires a defined reset condition. The demodulator generates automatically a reset signal after the power supplyV

is switched on,or ata voltage-drop.

DDA

microcontroller, or vice versa.

LIMITING VALUES

In accordance with the Absolute Maximum Rating System (IEC 60134).

SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT

lu(prot)

supply voltage 0 6.5 V voltage at pins 1 to 4, 7 to 10, and

13 to 16 with respect to pins 6 and 11 inputcurrent atpins 1 to 5, 7 to 11 and

13 to 16 latch-up protection current in pulsed

mode

pins 5 and 12 are connected to V

pins 6 and 11 are connected to ground

= −40 to +85 °C with

amb

voltage limiting −2 to +10 V T

=25°C with voltage

amb

−0.5 VDD+ 0.5 ≤ 6.5 V

−10 +10 mA

−100 +100 mA

−200 +200 mA

limiting −2 to +12 V

= −40 to +85 °C

amb

−10 +10 mA

without voltage limiting

amb

stg

ambient temperature −40 +85 °C storage temperature −65 +150 °C electrostatic handling voltage note 1 −4000 +4000 V

note 2 −500 +500 V

ref

Notes

1. Human body model (equivalent to discharging a 100 pF capacitor through a 1.5 kΩ series resistor).

2. Machine model (equivalent to discharging a 200 pF capacitor through a0 Ω series resistorand 0.75 µH inductance).

THERMAL CHARACTERISTICS

SYMBOL PARAMETER CONDITIONS VALUE UNIT

th(j-a)

thermal resistance from junction to ambient in free air 104 K/W

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