BA7797 View Datasheet(PDF) - ROHM Semiconductor
Part Name
Description
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BA7797 Datasheet PDF : 8 Pages
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Video ICs
•Operation notes
(1) ALC level
Set the ALC level in the range – 8dBV to 0dBV by con-
necting a resistor between pin 9 and GND.
VOA =
1
2
•
VCC – 0.7
2
•
4k
4k + 32k × R / (32k + R)
=
1
2
•
4k
+
32k
4k
×R
/
(32k
+
R)
•
VBIAS
The formula for approximating the value of this resistor
is as follows:
When pin 9 is open, VOA is preset to – 8dBV (for VCC =
10V).
Note that the supply voltage VCC has an effect.
BA7797F
VBIAS
ALC LEVEL ADJ
9
R
4k
ALC DET
32k
Fig.4
VBIAS = VCC – 0.7
2
9pin Voltage =
4k
32k × R
+ 32k ×
/ (32k +
R / (32k
R)
+ R)
•
VBIAS
(2) Mute signal
Apply the mute signal shown below at power on and off.
If the muting time is short, a “pop” sound will be audi-
ble, particularly when the power is switched on.
(H)
(H)
VCC
MUTE CTRL
2 sec. Min.
LINE OUT
Fig.5
Also, be certain to apply the mute signal when switch-
ing between PB / LINE / TU. In the case of LINE / TU
switching, it is possible to suppress switching noise by
applying a time constant to the signal, in which case it
is not necessary to apply the mute signal.
(3) Recording control
Do not switch the PB and REC modes on together.
This will cause faulty operation.
(4) Line output
The line output can drive a load resistance of up to 2kΩ.
Depending on the type of load, it can cause local oscil-
lation (eg. large capacitive loads that draw large cur-
rent), so caution is required. In particular, when there is
a possibility that the line output will be connected to a
shielded cable, or line cable, connect a resistor of about
1kΩ in series with the output so that the capacitive load
is not directly coupled to the IC output terminal.
7
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