LC78857V View Datasheet(PDF) - SANYO -> Panasonic
Part Name
Description
Manufacturer
LC78857V Datasheet PDF : 11 Pages
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LC78857V
• Attenuator data
The signal can be attenuated by inputting attenuation data (A2 to A9).
The attenuation specified by the attenuation data is given by the following formula:
20 • log —A—tte—nu—at—ion—d—ata— (dB)
128
Note: The attenuation is 0 dB when the data value is 7F (hexadecimal).
However, if A9 (the MSB) is 1, the A2 to A data is ignored and the prior attenuation setting is retained.
MSB
A9
A8
0
1
0
1
•
•
•
•
•
•
0
0
0
0
Attenuation data
A7
A6
A5
A4
1
1
1
1
1
1
1
1
•
•
•
•
•
•
•
•
•
•
•
•
0
0
0
0
0
0
0
0
LSB Attenuation level (dB)
A3
A2
1
1
0
1
0
–0.137
•
•
•
•
•
•
•
•
•
0
1
–42.14
0
0
–∞
If the attenuation level is changed from 0 dB to –∞ dB, the IC performs a soft muting operation. The soft muting time is
1/Fs × 1024. Also, the time required to change the attenuation follows the slope of the soft muting function.
If new attenuation data is input while the attenuation is changing, the attenuation level starts to change from the current
level to the newly specified level at that point.
Note: If the IC is initialized when the MODE pin is low, the IC is initialized with serial data values of A0 = A1 = A9 =
low, and A2 to A8 = high.
However, the LAT/ND must be held high during this initialization.
• When MODE is high: parallel input mode
In this mode, the speed (normal/double), deemphasis, and soft muting settings are specified with the LAT/ND,
SH/EMP, and DAT/MT pins. It is not possible to set the attenuation data in this mode.
· Normal speed/double speed setting
LAT/ND
L
H
Normal/double speed
Normal speed
Double speed
· Deemphasis setting
SH/EMP
Deemphasis
L
Off
H
On
The deemphasis function supports operation at fs = 44.1 kHz.
· Soft muting setting
The LC78857V uses the digital attenuator to implement a
soft muting function. If the input level applied to the
DAT/MT pin is changed from low to high, the
attenuation changes from 0 dB to –∞ dB. Inversely, if the
DAT/MT pin is changed from high to low, the
attenuation changes from –∞ dB to 0 dB.
The time required for the change is 1/fs × 1024.
DAT/MT
L
H
Soft muting
Off
On
No. 5537-7/11
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