BU7831KN_06 Datasheet, PDF (9/17 Pages) Rohm – Voice/Audio Mixer & Selector

・Attenuator
Each attenuator has 16 steps (4bit), which contains mute. ATT6L and ATT6R that is attenuator of the headphone output
has soft mute that decreases pop sound in switching. (ATT1 - 5 don't have this function.)
The amount of software depends on a capacitor to connect to the CSTEP terminal. Decide the value of a capacitor to
connect to the CSTEP terminal after you take pop volume and delay time into consideration because a fixed number
becomes the bottom mostly at the time of that switching.
ATT setting
ATT
ATT
Mute
HP output
Thsmute
Thsmute
Thsmute=200×103×CSTEP [S]
Fig.24
・Analog path part
About the internal pass circuit, the circuit that it has a path setting by the register turns it on. For example, when
MIXSEL*_0 is chosen with either ATT, ST1R input is chosen, and a group of input amplifiers of ST1R turns it on. And a
connected output amplifier is turned on when either input is chosen with MIXSEL* in the same way to the output circuit.
・Pop sound decrease circuit at the time of head phone output ON/ OFF
It has the function that decreases pop sound that occurs at the time of ON/ OFF of the headphone output (HPL and HPR).
When headphone output is chosen/non-chosen, it is the function that the DC output of the headphone output goes down
smoothly on falling/rising. Rising time is decided by the capacitor value that it is connected to the CSTART terminal.
Falling time is decided by the CSTART terminal and the coupling capacitor. Pop sound decreases as much as to be here if
rising/falling is smooth. Decide the value of a capacitor to connect to the CSTART terminal after you take pop sound,
rising/falling time into consideration because a fixed number becomes the bottom mostly at the time of that switching.
And do settlement of timing in consideration of this time when you make it turn ON/OFF by the continuance.
Pop sound is made when it switches in the middle of the descent of rising/falling.
Headphone ON/OFF
Headphone Output
(DC)
Thpout
Thpout=80.6×103×CSTART[S]
Fig.25
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