bh3866as ROHM Co. Ltd., bh3866as Datasheet - Page 23

• Manufacturer Part Number: bh3866as
• Description: Dual-line Serial Control Sound Processor Ic
• Manufacturer: ROHM Co. Ltd.

(10) Surround and pseudo-stereo effects
The internal blocks in the IC for the surround and pseu-
do-stereo effects are configured as shown above. The
feeling of the surround location and the stereo feeling of
the pseudo-stereo effect can be changed by varying the
amount of the effect. Also, the loop switch can be turned
on to create a pseudo-increase in the number of phase
shifter stages. Raising the gain of the effect level with
the loop switch on causes instability, however, so the
level of the effects should be kept at around 6dB or
below. In order to prevent a popping sound when switch-
ing between the surround and pseudo-stereo effects, the
switch on the stereo surround side of the SSTE should
be left in the ON position.
(11) The level of the surround effect
The level of the surround effect can be varied between 0
and 15dB, using I
ever, that this gain is not the total gain between input
and output. In precise terms, it specifies the effect level
control range of the surround signal for the SOUT pin.
(With single-side input and the stereo / surround effects:
V
Video ICs
CC
1) Surround
2) Pseudo-stereo effect
= 9V, f = 1kHz, V
P: Amount attenuated at phase shifter stage
E: Amount of surround effect
Rch
Lch
t: Time of delay caused by phase shifter
32
1
Rch
Lch
L + R
32
2
1
C BUS data. Please be aware, how-
IN
= 100mVrms, Ta = 25°C.)
L – R
Configured externally
BPF
Phase shifter
t
P
Phase shifter
t
P
Effect adjustment
Effect adjustment
E
Fig.13
Fig.14
(12) Pin 17 (DAC) output
Setting the DAC command for the I
enables 5V output, and setting it to LOW enables 0V
output.
(13) BASS command
Creating an external LPF with the signals (L + R) output
from ADD (pin 29) and inputting those signals to BIN
(pin 28) enables configuration of a low-pitch amplifica-
tion circuit. This switch serves as the I
mand. The gain for the amplifier can be set through the
external resistance, using BGAIN (pin 26).
E
LPF
B
Gain = 20log
28
IN
+
+
LPF
1
2 V
+
+
CC
50k
+
–
+
+
26
10k + R
+
+
R
20
12
10
1
+
R
–
+
–
Fig.15
1
10k
L
R
OUT
OUT
1
= L + t (L – R) EP
= R + t (R – L) EP
20
12
L
R
OUT
OUT
= L + t (L + R) EP
BASS SW
= R – t (L + R) EP
2
2
C BUS bass com-
BH3866AS
C BUS to HIGH
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