E-TDA7478AD

TDA7478 Single chip RDS demodulator Features ■ Very high RDS demodulation quality with improved digital signal processing ■ High performance, 57 kHz bandpass filter (8th order) ■ Filter adjustment free and without external components ■ Purely digital RDS demodulation without external components ■ RDS signal quality output ■ 4.332 MHz crystal oscillator (8.664 MHz optionaL) ■ Low noise cmos technologY ■ Low radiation *$3*36 TSSOP16 Description The TDA7478 recovers the additional inaudible RDS information which is transmitted by FM radio broadcasting stations and operates in accordance with the EBU (European Broadcasting Union) specifications. Table 1. 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. Device summary Order code Package E-TDA7478AD Packing Tube TSSOP16 E-TDA7478ADTR September 2013 Tape and reel Doc 10679 Rev 4 1/11 www.st.com 11 Contents TDA7478 Contents 1 2 Block diagram and pins description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Pins description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.3 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 Output timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 4 Oscillator controls (FSEL, OSEL) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5 Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2/11 Doc 10679 Rev 4 TDA7478 Block diagram and pins description 1 Block diagram and pins description 1.1 Block diagram Figure 1. Block diagram &S) 7 0+] 26&,1 26&287   &S)   03; QG25'(5 $17,$/,$6,1* ),/7(5 S)  26&,//$725 ',9,'(5   ),/287 WK25'(5 6&%$1'3$66 ),/7(5  +] 3// .+]3//    96 48$/'(7 26(/ )6(/ 5'&/ 18 48$/ Q) 95()    32/$5,7< %,3+$6('(&   P) 08; ',))'(&2'(5  ,17(*5$/ %,3+$6('(&   7(67/2*,& 5''$ 70  *1' (;75(6 Doc 10679 Rev 4 *$3*36 3/11 Block diagram and pins description 1.2 TDA7478 Pins description Figure 2. Pin connection (top view) 48$/   5'&/ 5''$   7 95()   26&287 03;   26&,1 26(/   96 *1'   (;75(6 18   70 ),/287   )6(/ *$3*36 Table 2. Pin # Name 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: – open, closed to VS = quartz oscillator – closed to GND = external driven 6 GND Ground 7 N.U. Not Used (to be left open) 8 FILOUT Description Filter output Frequency selector pin: – open = 4.332 MHz – closed to VS = 8.664 MHz 9 FSEL 10 TM 11 EXTRES 12 VS Supply voltage 13 OSCIN Oscillator input 14 4/11 Pins description Test mode pin: – open = normal operation – closed to VS = testmode Reset pin: – open = run mode – closed to VS = reset condition OSCOUT Oscillator output 15 T57 16 RDCL Testing output pin: 57 kHz clock output RDS clock output 1187.5 Hz Doc 10679 Rev 4 TDA7478 Electrical specifications 2 Electrical specifications 2.1 Thermal data Table 3. Thermal data Symbol Rth j-case 2.2 Description Thermal resistance junction-to-case Unit 200 °C/W Value Unit Absolute maximum ratings Table 4. Absolute maximum ratings Symbol 2.3 Max. Value Parameter VS Supply voltage -0.3 to 7 V Top Operating temperature range -40 to 85 °C Tstg Storage temperature -55 to 150 °C Electrical characteristics Tamb = 25°C, VS = 5V, unless otherwise specified. Table 5. Electrical characteristics Symbol Parameter Test condition Min. Typ. Max. Unit VS Supply voltage - 4.5 5 5.5 V IS Supply current - - 7.5 12.0 mA Filter fC BW G A Center frequency - 56.6 57 57.4 kHz 3 dB bandwidth - 2.5 3 3.5 kHz Gain f = 57 kHz 17 20 23 dB Δf ± 4 kHz - 22 - dB f = 38 kHz - 60 - dB f = 67 kHz - 45 - dB Attenuation RI Input impedance of MPX - - 120 - KΩ RL Load impedance on FILOUT - 1 - - MΩ S/N Signal to noise ratio VIN = 3 mVRMS 30 40 - dB (1) VIN SRDS MPX input signal f = 19 kHz; T3 ≤ 40 dB f = 57 kHz (RDS) - - 1000 50 mVRMS mVRMS RDS detection sensitivity - 1 - - mVrms Doc 10679 Rev 4 5/11 Electrical specifications Table 5. TDA7478 Electrical characteristics (continued) Symbol Parameter Test condition Min. Typ. Max. Unit SARI ARI detection sensitivity - 3 - - 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 = 5 V (pull-down input) 15 - 30 μA IPU Input current VIN = 0 V (pull-up input) -25 - -10 μA VIH Input voltage high - - V VIL Input voltage low - - 0.7 · VS 0.8 · VS 0.2 · VS 0.3 · VS V Output pins (RDCL, RDDA, QUAL, T57) VOH Output voltage high IL = 0.5 mA 4 4.6 - V VOL Output voltage low IL = 0.5 mA - 0.4 1 V Oscillator VCLL Input level OSCIN pin OSEL = open circuit - - 1 V Input level OSCIN pin OSEL = open circuit 4 - - V Amplitude OSCOUT OSEL = open circuit - 4.5 - V Amplitude OSCIN (for external drive) OSEL = GND, f = 4.332 MHz OSEL = GND, f = 8.664 MHz - 100 120 - mVpp mVpp VCLH VPP 1. The 3rd harmonic (57 kHz) must be less than -40 dB with respect to the input signal plus gain. 6/11 Doc 10679 Rev 4 TDA7478 3 Output timing 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 Figure 3). Whichever clock edge is used by the decoder (rising or falling edge) the data will remain valid for 416.7 μs after the clock transition. Figure 3. RDS timing diagram 5'&/ &/2&. /,1( '$7$ /,1( 5''$ —V WG —V —V —V —V *$3*36 Doc 10679 Rev 4 7/11 Oscillator controls (FSEL, OSEL) 4 TDA7478 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 frequencies Crystal 4.332MHz 8.664MHz FSEL (pin configuration) 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 60 mV. 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. 8/11 C1 and C2 suggested value Crystal C1 C2 4.332MHz 8.664MHz 27pF 27pF 47pF - Doc 10679 Rev 4 TDA7478 5 Package information Package information In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark. Figure 4. TSSOP16 mechanical data and package dimensions PP LQFK ',0 0,1 7