s ilicore shaoxing silicore technology co.,ltd www. silicore. com. cn chmc 1/3 electronic two-tone ringer SC1240 description outline drawing the SC1240 are monolithic integrated circuits designed to replace the mechanical bell in telephone sets in connection with an electro-acoustical converter. the devices can drive directly a piezoceramic converter (buzzer). the two tone frequencies generated are switched by an internal oscillator in a fast sequence and made audible across an output amplifier in the loudspeaker , both tone frequencies and the switching frequency can be externally adjusted. the signal and the circuit is designed so that noise on the line or vari ations of the ringing signal cannot affect correct operation of the device. feature z low current consumption, in order to allow the parallel operation of 4 devices. z integrated rectifier bridge with zener diodes to protect against over voltage. z integrated voltage and current hysteresis z little external circuitry. z tone and switching frequencies adjustable by external components. block diagram pin connection rectifier threshold circuit with hysteresis output switching frequency tone frequency generator line rectifier capacitor null buzzer control capacitor line gnd sweep rate 12 3 4 5 7 6 8 output frequency control resistor line ground sweep rate control capacitor output frequency control resistor line null rectifier buzzer 1 8 2 7 3 6 4 5 capacitor bridge generator stage in in
silicore SC1240 shaoxing silicore technology co.,ltd www. silicore. com. cn chmc 2/3 absolute maximum ratings (ta=25 c) characteristic symbol value unit calling voltage (f=50hz) continuous vab 120 vrms calling voltage (f=50hz) 5s on/10s off vab 200 vrms supply current idc 30 ma operating temperature topr -20~+70 ?? storage temperature tstg -65~+150 ?? thermal resistance junction-ambient rth-amb 200 ?? /w electrical characteristics (unless otherwise specified: ta=25 c, vs=applied between pins 7-2) characteristics test conditions symbol min. typ. max. unit supply voltage - vs - - 26 v current consumption without load vs=9.0~25.0v i b - 1.5 1.8 ma actination voltage - v on 12.2 - 13.2 v sustaining voltage - v off 8 - 9.3 v differential resistance in off condition - r d 6.4 - - k |? output voltage swing - v out - vs-5 - v short circuit current vs=20v ? r l =250 |? i out - 70 - ma ac operation vs=0v fout1 1.74 1.95 2.14 output frequency vs=26v ? r i =14k |? vs=3v fout2 1.22 1.40 1.6 khz fout1/fout2 1.33 1.43 programming resistor range 8 5.6 k |? sweep frequency r i =14k |? c1=100nf fsweep 5.25 7.5 9.75 hz
silicore SC1240 shaoxing silicore technology co.,ltd www. silicore. com. cn chmc 3/3 test circuit r1 14k c1 100nf vout rl 10uf 2.2k 1uf vab sc 1240 4 3 2 1 7 5 8 5 7 1 2 3 4 f1= 27200/r1(k |? ) f2=0.72511f1 f (sweep)=750/c1(nf) application circuit r1 14k c1 100nf 10uf 2.2k 1uf vab line sc 1240 4 3 2 1 7 5 8 5 7 12 3 4 buzzer zload >1k r1 14k c1 100nf 10uf 2.2k 1uf vab line sc 1240 4 3 2 1 7 5 8 5 7 12 3 4 cl rl=50~1000
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