ka9270 audio filter introduction the ka9270 is a monolithic integrated circuit designed for audio filter. it is used in compact disc player, digital audio tape recorder, etc. features functions: gain adjustable of audio output minimum number of external parts required recommand operation supply voltage range : 5.0 ~ 12.0v block diagram device package operating temperature ka9270 20-dlp-300a KA9270D 20-sop- 375 20 19 18 17 16 15 14 1 3 12 11 1 2 3 4 5 6 7 8 9 10 - + - + - + - + - + mute sw de-em sw - + - + buffer2 buffer1 de-amp2 de-amp1 vcc lpf1 lpf2 lpf output2 lpf2b v ref ripple de-empha ctl de-empha out2 de-empha in3 buffer out2 input2 1/2vcc-amp gnd lpf output1 lpf1b mute control input de-empha control input de-empha ctl de-empha out1 de-empha in1 buffer out1 input1 20 c ~ +75 c 20-dip-300a 20-sop-375 fig. 1 * buffer for impedence matching * low pass filter * de - emphasis control * mute control * reference voltage circuit ( 1/2 v cc amp )
ka9270 audio filter absolute maximum ratings (ta = 25 c) electrical characteristics (ta = 25 c, v cc = 8v, f = 1khz, r l = 10k w , de-emphasis; off, mute; off, s1 & s2; off, unless otherwise specified) note: de-emphasis input conditions: v o = 0dbm de-emphasis off position characteristic symbol value unit supply voltage power dissipation operating temperature storage temperature v cc p d t opr t stg 16 550 -20 ~ + 75 -45 ~ + 150 v m w c c characteristic symbol test conditions min typ max unit quiescent circuit current i cc v i = 0 1 4 6 ma maximum output voltage v om thd = 1% 1.8 2.1 vrms f = 100hz 0.01 0.05 f = 1khz 0.01 0.05 total harmonic distortion thd v o = 0dbm f = 10khz 0.05 0.1 % f = 16khz 0.1 0.2 f = 20khz 0.1 0.2 f = 100hz -0.1 0 0.1 f = 1khz 0 0 0 frequency characteristics fv v o = 6dbm f = 10khz -0.5 0 0.5 db f = 16khz -1.0 0 1.0 f = 20khz -1.5 0 1.5 f = 100hz 70 80 cross talk ct v o = 0dbm f = 1khz 65 75 db f = 10khz 60 65 signal to noise ratio s/n v o = 0dbm, r g = 600 w 20khz lpf 73 80 db channel balance cb v o = 0dbm -1.0 0 1.0 db open loop gain g vo v i = 900mvrms -2.6 -0.6 1.0 db gain adjusting range g vr v i = 900mv, s1, s2; on 4.5 6 db mute attenuation ratio att mute v i = 900mv, mute sw; on 40 50 db f = 1khz -0.87 -0.37 0.13 de-emphasis de emph de-emphasis: on f = 5khz -6.03 -4.53 -3.03 db f = 16khz -10.53 -9.03 -7.53
ka9270 audio filter test circuit fig. 2 + 20 19 18 17 16 15 14 1 3 12 11 1 2 3 4 5 6 7 8 9 10 + + + - + - + - + - + mute sw de-em sw - + - + + + ch2 output (vo) 3.3 t vcc 47 t 0.01 t 10k 330pf 5.6k 0.0015 t 1/2 vcc 5.6k 5.6k 4.7 t 1m 0.0012 t 12k 27k 27k 4.7 t 5k ch2-input (from signal generator output) + - vi 1/2 vcc buffer2 buffer1 ch1-input (from signal generator output) de-amp2 de-amp1 vcc lpf1 lpf2 ch1 output (vo) 10k 3.3 t 330pf 5.6k 5.6k 0.0015 t mute control signal (mute) de-emphasis control signal (de-em) 5.6k 27k 27k 12k 1m 0.0012 t 4.7 t 5k vi + - - +
ka9270 audio filter application information 1. buffer fig. 3 it is used for impedance matching, between d/a converter output and de-emphasis input. 2. de-emphasis a) de-emphasis operation condition b) de-emphasis characteristic at the de-emphasis on fig. 4 equevalent circuit of de-emphasis on mode the de-emphasis charcteristics is dependent on the external parts value. + - input (from d/a converter output) to de-emphasis input control input de-emphasis operation high on low off + - vi r6 r5 r4 vo c1 av r 4 / r 6 t1 = c1 (r 4 + r 5 ) t2 = c 1 x r 5
ka9270 audio filter 3. mute fig. 5 equivalent circuit of mute switch on mode mute attenuation [m (att)] ratio is as follow; m (att) = 20 log = 20 log (db) 4. low pass filter fig. 6 equivalent circuit of lpf cut off frequency (f c ) is as follow: f c = (hz) + - vi r6 vo r qon + - vi r3 r2 r1 c4 c3 where: r qon = internal tr on resistance v o v i r qon r 6 1 2 p ? r 2 r 1 c 3 c 4
ka9270 audio filter application circuit fig. 7 20 19 18 17 16 15 14 1 3 12 11 1 2 3 4 5 6 7 8 9 10 + + + - + - + - + - + mute sw de-em sw - + - + + + ch2 output 3.3 t vcc r l 10k 330p 5.6k 1/2 vcc 5.6k 4.7 1m 120up 12k r9 27k 27k 4.7 c8 ch2-input (from dac output) buffer2 buffer1 ch1-input (from dac output) de-amp2 de-amp1 vcc lpf1 lpf2 ch1 output (vo) r l 10k c5 3.3 330p 5.6k r1 1500p mute control signal (mute) de-emphasis control signal (de-em) 5.6k 27k 27k 12k 1m 1200p c7 4.7 c10 r12 c9 1500p r11 + 10 c8 c7 5.6k r10 r8 r7 c4 r2 c3 + 10u r3 r4 r6 c2 - +
ka9270 audio filter (pcb pattern)
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