BU7831KN_10 Datasheet, PDF (9/17 Pages) Rohm – Voice/Audio Mixer & Selector IC

BU7831KN
Technical Note
・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
T hpout= 80. 6×103× CS TA RT [S]
Fig.25
・Digital part
Input such as clock, data is to input "H" or "L" properly about each digital input terminal to contain at the time of standing by
as well. If you turn off the power (When Hi-z is input), a control side is to avoid an input terminal's becoming open in either
following method It has the possibility that penetration electric current occurs because it becomes the input which isn't
fixed as BU7831KN when it isn't avoided.
a） Terminal, in less than 10kΩ, pull-down
b） Terminal, pull-up
c） When it becomes input Hi-z, "L" is given to it.
・CPU interface
NCS
tcs
tcyc
tch
SCLK
tds
tdh
SDATA
A7 A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0
Fig.26
SDATA will be confirmed by 16^th clock that is inputted after NCS falling edge, and then serial data reflect to internal register
by NCS falling edge. The data format is 16bit rear.
CPU I/F is 1Byte=16bit. Because it doesn't cope with continuous data transmission, you must surely insert the section of
NCS= "H" between 1st Byte and 2nd Byte. The following the is to secure time beyond the SCLK 1 clock. (th≧tcyc)
th
NCS
SCL
SDATA
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Fig.27
9/16
2010.09 - Rev.A