BU9253AS_05 Datasheet, PDF (13/17 Pages) Rohm – Karaoke/Surround Digital Echo

・LPF and echo system gain
When the ratio of original signal and echo is changed, R5, R6, R9, R11 are also changed, and the characteristics of LPF
change too. Therefore, it is necessary to change all the constants of LPF. In the case, to precisely measure the ratio of
original signal and echo, remove R7, input signal around 500Hz without the influence of LPF from MIX IN, and compare
it with the output of DALPF OUT.
R4
R11
C4
C8
R5
R6
R9
R10
IN
－
C5
C7
＋
fc =
1
2π C4C5R4R5
Q=
1
R _{4R 5}
+
R _{4R 5}
R6
C5R _{4R 5}
C4
QQgはen一er般al的lyにab0o.7uぐt 0ら.7い
OUT
A1
=
R4
R5
A2
=
R11
R9
Eエchコo －sig信n号al 増am幅p率litude ratio
Fig.35 LPF and echo system gain
=
A1 ×
A2
=
R ₄ × R11
R5 ×R9
・Clock oscillation
As for C,R, tolerance should be below 5%. Note: If measurement is made by attachment a probe oscilloscope it might
load the oscillator and reduce the oscillation frequency.
* The set values in this document are for reference only. In the actual set, characteristics may change according to board
layout, wiring, types of parts used, and therefore, in actual use, carry out sufficient verification with the actual devices.
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