BA336 Datasheet, PDF (4/7 Pages) Rohm – Mute detector IC

Audio ICs
BA336 / BA338 / BA338L
FCircuit operation
The BA336 / BA338 / BA338L operates according to
the timing shown in Fig. 2. When the input signal is below
the input decision level, the electrical potential of Pin 2
begins to rise according to the time constant set by CD
and RD. When it reaches 1 / 2 of VCC, the comparator
which sets the mute detection time inverts. At this point
the potential of Pin 1 begins to rise according to the time
constant set by CW and RW, and when it reaches 1 / 2 of
VCC, the pulse width comparator inverts. During the inter-
val from the inverting of the mute detection time
comparator to the inverting of the pulse width compara-
tor, the output is high. When the power is turned on or
muting is turned off, a reset pulse is generated for a cer-
tain period of time (determined by the Pin 6 capacitor),
the internal flip-flop resets, and an output pulse is not
generated. When an input signal comes in after this, the
flip-flop resets, mute detection goes on standby, and an
output pulse is obtained with each song gap.If the mute
time is TM, the song detection time TD and the output
pulse width TW must be selected so that TD ) TW < TM.
Furthermore, TD must be made longer than any periods
of silence in songs.
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