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 technology low radiation description the tda7331, an improved version of tda7330b, recovers the additional inaudible rds information which is transmitted 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 section that performs the extraction 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 2 vref 100nf 10 m f oscillator & divider 57khz pll fast ari indicator polarity biphase dec. integral biphase dec. 1187.5hz pll mux 0 1 diff. decoder test logic qual det. 5 gnd n.c. 6,7,8,17 20 extres 9 10 3 18 12 15 14 d97au686b tm 19 rdda 13 qual ari rdcl fsel osel oscout oscin 4.332mhz c2 47pf c1 27pf 11 t57 block diagram and test circuit tda7331 single chip rds demodulator + filter dip20 so20 ordering numbers: tda7331 tda7331d 1/7
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 extres 20 19 18 17 16 14 15 13 12 d97au687 oscin 10 t57 11 pin connection absolute maximum ratings symbol parameter value unit v s supply voltage 7 v t op operating temperature range -40 to 85 c t stg storage temperature -55 to 150 c pin function n o 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 connected 7 nc not connected 8 nc not connected 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 connected 18 fsel frequency selector pin: - 100k to v s = 17.328mhz - open = 4.332mhz - closed to v s = 8.664mhz 19 tm test mode pin: - open = normal operation - closed to v s = testmode 20 extres reset pin: - open = run mode - closed to v s = reset condition tda7331 2/7
thermal data symbol description dip20 so20 unit r th j-amb thermal resistance junction-ambient max 100 200 c/w electrical characteristics (t amb = 25c, v s = 5v, unless otherwise specified). symbol parameter test condition min. typ. max. unit v s supply voltage 4.5 5 5.5 v i s supply current 7.5 11.0 ma filter f c center 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 d f 4khz 18 22 db f = 38khz 50 60 db f = 67khz 35 45 db r i input impedance of mpx 80 120 150 k w r l load impedance on filout 1 m w s/n signal to noise ratio v in = 3mv rms 30 40 db v in mpx input signal f = 19khz; t3 40db(1) f = 57khz (rds+ ari) 1000 50 mv rms mv rms v ref reference v s /2 v demodulator input pins (extres, fsel, tm) all with internal pull down resistor input pin (osel) w ith internal pull up resistor i pd input current v in = 5v (pull-down input) 15 30 m a i pu input current v in = 0v (pull-up input) -25 -10 m a v ih input voltage high 0.7 v s 0.8 v s v v il input voltage low 0.2 v s 0.3 v s v output pins (rdcl, rdda, ari, qual, t57) v oh ouput voltage high i l = 0.5ma 4 4.6 v v ol output voltage low i l = 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 v pp 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. tda7331 3/7
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 m sec 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 mode is introduced to reduce emi. with 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 tda7331 4/7
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 tda7331 5/7
11 0 11 20 a e b d e l k h 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 mechanical data tda7331 6/7
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