1 multimedia ics karaoke echo ic BU9253as / BU9253fs / bu9255fs the BU9253as, BU9253fs and bu9255fs are single-chip ics that contain all the components needed to configure a karaoke echo system: an a / d and d / a converter, sram, lpf, and mixer for mixing source signals. with these ics, an echo function can be configured easily and with minimum external components. applications karaoke functions for portable stereo sets, mini com- ponent stereo sets, video cds and dvds, etc. features 1) echo mixing ratio is adjustable with a dc voltage. 2) a second order lpf can be configured with the internal amplifier and an attached capacitor and resistor. 3) delay time of 131ms. (when f clk = 357khz) 4) internal mute function. 5) single power supply (5v). block diagram BU9253fs / bu9255fs BU9253as 1 counter v cc a / d sram d / a osc 2345678 16 15 14 13 12 11 10 9 mix 12345678 9 counter v cc a / d sram d / a osc 16 15 14 13 12 11 10 mix 18 17 + ? + ? + ? + ?
2 multimedia ics BU9253as / BU9253fs / bu9255fs pin descriptions BU9253fs / bu9255fs BU9253as pin no. pin name function 1 gnd 2 echo vr 3 bias 4 daint in 5 daint out 6 dalpf in 7 dalpf out 8 mix out 9 mix in 10 adlpf in 11 adlpf out 12 adint out 13 adint in 14 v cc 15 mute 16 cr analog dc bias da integrator input echo level dc control da integrator output da lpf input da lpf output source sound and echo sound mixing output mixing amplifier source sound input ad lpf input ad lpf output ad integrator output ad integrator input vcc mute control oscillator output ground absolute maximum ratings (ta = 25?) parameter symbol limits unit applied voltage v cc 7v power dissipation pd 500 * 1 600 * 2 BU9253fs BU9253as 500 * 1 bu9255fs mw operating temperature topr ?10 ~ + 70 c storage temperature topr ?55 ~ + 125 c input voltage v in ?0.3 ~ v cc + 0.3 v * 1 reduced by 5.0mw for each increase in ta of 1 c over 25 c. * 2 reduced by 6.0mw for each increase in ta of 1 c over 25 c. recommended operating conditions (ta = 25?) parameter power supply voltage v cc 4.0 5.5 v 5.0 symbol min. typ. max. unit pin no. pin name function 1 gnd 2 echo vr 3 n.c. 4 bias 5 daint in 6 daint out 7 dalpf in 8 dalpf out 9 mix out 10 mix in 11 adlpf in 12 adlpf out 13 adint out 14 adint in 15 v cc 16 17 18 n.c. mute cr ground echo level dc control internally analog dc bias da integrator input da integrator output da lpf input da lpf output source sound and echo sound mixing output mixing amplifier source sound input ad lpf input ad lpf output ad integrator output ad integrator input vcc internally mute control oscillator output
3 multimedia ics BU9253as / BU9253fs / bu9255fs electrical characteristics (ta = 25?, v cc = 5.0v, f clk = 375khz, f = 1khz, v i = - 10dbv, pin 2 = v cc , pin 15 = v cc , distortion = 400hz ~ 30khz filter, output noise voltage : din-audio) *pin no. are for BU9253fs , bu9255fs and BU9253as parameter symbol min. typ. max. unit conditions v om2 1.4 1.7 v rms v no2 90 ?80 dbv g v2 ?1 0 1 db g v1 ?5.6 ?3.5 ?1.4 db f c 375 khz v l 0 0.7 v v m 1.6 2.8 v v h 3.8 5.0 v v om1 1.4 1.7 v rms v no1 80 ?60 dbv thd2 0.02 0.1 % thd1 1.5 3 % i cc 6 12 ma current consumption voltage gain 1 voltage gain 2 output distortion 1 output distortion 2 output noise voltage 1 output noise voltage 2 max. output voltage 1 max. output voltage 2 mute control oscillation frequency no signal delay total gain in1 ? out through total gain in2 ? out, pin2 = ground delay side through, pin2 = ground delay, rg = 1k w through side rg = 1k w , pin2 = ground delay, thd = 10% through side, thd = 1 % pin 2 = ground h mode hold voltage, pin 15 dc m mode hold voltage, pin 15 dc l mode hold voltage, pin 15 dc
4 multimedia ics BU9253as / BU9253fs / bu9255fs measurement circuit (for BU9253fs / bu9255fs) v cc v cc 100 m 0.1 m 0.01 m 0.012 m 2.2 m 20k 8.2k 1k 2.2 m in1 in2 1k 4700p 10k 100p 39k mix 2.2 m 22k resistor : [ w ] unit capacitor: [f] out 3300p 15k 10k 4.7k 0.01 m 0.01 m 22 m v cc 1 2 34 5678 0.47 m d / a sram a / d osc 16 15 14 13 12 11 10 9 counter + ? + ? fig. 1
5 multimedia ics BU9253as / BU9253fs / bu9255fs ?when switching between the muted and unmuted state (pin 15 (pin 17) l ? m ? h), the pin 15 (pin 17) m time should be longer than one sram cycle. this is to assure stability by initializing the sram before mode switching. note: figures in parentheses ( ) are for BU9253as. (2) differences between BU9253as / fs and bu9255fs there is a difference regarding the signal stopping for muting. with BU9253as / fs, the output from pin 8 (pin 9) is stopped during muting. with bu9255fs, the output from pin 5 is stopped during muting. application example (for BU9253fs / bu9255fs) v cc v cc 100 m 0.1 m 0.01 m 0.012 m 20k 20k 8.2k in 4700p 10k 100p 39k mute mix 2.2 m 2.2 m resistor : [ w ] unit capacitor: [f] out 3300p 15k 10k 4.7k 0.01 m 0.01 m 22 m echo level 12345678 0.47 m d / a sram a / d osc 16 15 14 13 12 11 10 9 counter fig. 2 + ? + ? + + + (1) mute control functions h unmuted (operating state) m muted l clock stop and muted pin 15 voltage (pin 17) mode
6 multimedia ics BU9253as / BU9253fs / bu9255fs external dimensions (units: mm) ssop-a16 0.51min. 0 ~ 15 7.62 3.95 0.3 1.778 10 9 6.5 0.3 19.4 0.3 18 1 0.5 0.1 3.4 0.2 0.3 0.1 sdip18 BU9253as BU9253fs / bu9255fs 0.36 0.1 0.8 0.11 6.6 0.2 4.4 0.2 6.2 0.3 1.5 0.1 1 16 8 9 0.15 0.3min. 0.15 0.1 (3) setting the echo loop gain v in lpf r r ad sram odb v in v o vdly recommendable gain + 3db recommendable gain ?6db r: r = 1: 1 mix echo loop att v in ~ v dly ? = (a < 1) * with pin no. BU9253fs v in v dly out da 2 vr 9 7 8 fig. 3 + + with v omax being the maximum amplitude of v o at this time (when the phases, including that of the dly cir- cuit, are in alignment): thus, maximum allowable input is the value of v omax provided the specifications (1 = a). assuming a feed- back ratio (a) of 0.7 and a maximum v out of 4.0 v p-p , v in must be less than 1.2 v p-p . v o max. = (1 + a + a2 + ? v in = 1 1-a s k = 0 a k ?v in = v in
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