Toshiba TA8266HQ, Руководство по описанию и применению

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TA8266HQ
2006-04-28
4
3. Muting Function
(pin 22)
By means of controlling pin 22 less than 0.5 V, it can make the audio muting condition.
The muting time constant is decided by R
1
and C
4
and these parts is related the pop noise at power
ON/OFF.
The series resistance; R1 must be set up less than 10 k Ω to get enough muting attenuation.
The muting function have to be controlled by a transistor, FET and micro-controller port which has
I
MUTE
> 250 µ A ability.
Pin 22 terminal voltage has the temperature characteristics of 4.6 V (low temperature) to 3.2 V (high
temperature).
Therefore, it is need to design with attention as using the micro-controller of which operating voltage is
less than 5 V.
Terminal 22 may not be pulled up and shall be controlled by OPEN/LOW.
When it is obliged to do, it must be pulled up via diode, because it has to defend flowing reverse current
to internal circuit of pin 22.
V
CC
Small current capacity switch
BATTERY
Stand-By V
CC
DIRECTLY FROM
MICROCOMPUTER
BATTERY
Stand-By
– Stand-by Switch Method –
Figure 3
– Conventional Method –
V
CC
Large current capacity switch
BATTERY
V
CC
FROM
MICROCOMPUTER
BATTERY
RELAY
Figure 5 Mute Attenuation
−
V
MUTE
(V)
Point A voltage: VMUTE (V)
ATT – V
MUTE
Mut
e
a
tte
nu
a
tio
n
AT
T
(d
B
)
10 k
Ω
5 k
Ω
VCC
=
13.2 V
Po
=
10 W
PL
=
4
Ω
f
=
1 kHz
−
100
0 0.4 0.8 1 1.2 1.6 2 2.4 2.8 3
−
80
−
60
−
40
−
20
0
20
Figure 4 Muting Function
R
1
I (100
µ
A)
22
I
MUTE
I
MUTE (OFF)
A
V
MUTE
C
4
<Recommended Application>
<Application for pulled up>
R
1
I (100
µ
A)
22
I
MUTE
I
MUTE (OFF)
V
MUTE
C
4