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SM5852DS Datasheet, PDF (11/14 Pages) Nippon Precision Circuits Inc – Digital Audio Processor LSI | |||
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FUNCTIONAL DESCRIPTION
Signal Flow
SM5852DS
Lch. IN
ASC
Rch. IN
ASC
LIVE
Soft Mute
Lch. OUT
XBS
Soft Mute Rch. OUT
ASC Function
The ASC (train position) function uses a 7 kHz band-
limited ï¬lter to cut-off sound leakage from
headphones. The ASC function is OFF when OPT is
HIGH, and ON when OPT is LOW.
LIVE Function
The LIVE (pseudo-sound ï¬eld) function emphasizes
the extent of the sound ï¬eld by adding an inverse
phase component from the opposite channel of the
input signal. When used with the XBS function, low-
frequency components of the spectrum are further
emphasized.
The LIVE function is OFF when DB/DS is HIGH,
and ON when DB/DS is LOW. Note that the function
is also OFF when both MOD1 and MOD2 are HIGH.
XBS Function
The XBS (extra bass system) function emphasizes
the low-frequency end of the spectrum by changing
the gain for low-frequency components of the input
signal. The XBS gain is set by the states of MOD1
and MOD2. Note that the gain changes when the
XBS function is used together with the LIVE
function.
DB/DS
LOW
LOW
LOW
LOW
HIGH
HIGH
HIGH
HIGH
MOD1
LOW
LOW
HIGH
HIGH
LOW
LOW
HIGH
HIGH
MOD2
LOW
HIGH
LOW
HIGH
LOW
HIGH
LOW
HIGH
Maximum gain
+13 dB
0 dB
+4 dB
0 dB
+10 dB
+13 dB
+6 dB
0 dB
Mode
XBS + LIVE
LIVE
XBS + LIVE
Off
XBS
XBS
XBS
Off
Soft Muting
Soft muting is active when MUTEN is LOW. When
MUTEN is LOW, the attenuation changes smoothly
from 0 to ââ dB in 1024/fs, or approximately 23.2
ms.
When MUTEN goes HIGH, soft muting is released
and the attenuation changes smoothly from ââ to 0
dB, again taking approximately 23.2 ms.
Also, if a MUTEN transition occurs while the
attenuation is changing, the attenuation then changes
smoothly in the direction speciï¬ed by the new level
of MUTEN.
DB/DS, OPT Switching Shock Noise
The soft muting function is also activated to
eliminate switching shock noise when DB/DS or
OPT change state. When DB/DS or OPT change
state, the attenuation changes to ââ dB, the internal
circuit settings are activated and then soft muting is
released. Therefore, a maximum time of
approximately 46.4 ms is required to change the
compression mode. Of course, if the attenuation is
already ââ dB after soft muting using MUTEN, then
no time is required to change compression mode.
Reset Initialization
RSTN should be set LOW at power-ON and after
reacquiring synchronization. Note that if RSTN is
LOW for longer than 1 µs, a through-current ï¬ows in
the LSIâs internal dynamic circuits because the
internal clock is stopped. The through-current has no
rated value, so the reset pulse should be kept as short
as possible at all times other than at power-ON.
When RSTN goes from LOW to HIGH, initialization
hold is released and the initialization routine ï¬rst
resets the internal data over an interval of 4fs. During
the initialization routine, the output data is forcibly
muted so that there is no output signal.
NIPPON PRECISION CIRCUITSâ11
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