SM5852CS Просмотр технического описания (PDF) - Nippon Precision Circuits
Номер в каталоге
Компоненты Описание
производитель
SM5852CS Datasheet PDF : 17 Pages
| |||
SM5852CS
FUNCTIONAL DESCRIPTION
Dynamic Range Compression
Dynamic range compression varies the effective
amplification of the input as a function of the input
signal level. The mode control block selects one of 6
dynamic range compression characteristics
according the states of DB/DS, MOD1 and MOD2.
Also, dynamic range compression can be turned
OFF, bypassing all processing.
DB/DS
LOW
LOW
LOW
LOW
HIGH
HIGH
HIGH
HIGH
MOD2
LOW
LOW
HIGH
HIGH
LOW
LOW
HIGH
HIGH
MOD1
LOW
HIGH
LOW
HIGH
LOW
HIGH
LOW
HIGH
Compression mode
6
5
4
Off
3
2
1
Off
Attack Time Selection
The input interface block incorporates a peak hold
circuit to determine the input level. The peak hold
circuit has a time constant of τ = 250 ms, and the
peak hold output is attenuated and then compared
with the next input level. Therefore, the dynamic
range compression recovery time constant is
effectively τ = 250 ms.
The attack time coefficient of the input signal, to
pass through the selected attack time LPF, is
determined by the input level.
Two attack time low-pass filter characteristics are
available, selected by the state of OPT.
s OPT = HIGH, Attack-1 characteristics, fC = 350
Hz, 2nd-order LPF (Q = 0.5)
s OPT = LOW, Attack-2 characteristics, fC = 150
Hz, 2nd-order LPF (Q = 0.5)
The attack time is the time required by the circuit to
return to the set value after a sudden increase in the
input. The recovery time is the time required by the
circuit to return to the set value after a sudden
decrease in the input.
Soft Muting
Soft muting is active when MUTEN is LOW. When
MUTEN is LOW, the attenuation changes smoothly
from 0 to −∞ dB in 1024/fs, or approximately 23.2
ms.
When MUTEN goes HIGH, soft muting is released
and the attenuation changes smoothly from −∞ 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 specified 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 −∞ 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 −∞ 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 flows in
the LSI’s 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 first
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 CIRCUITS—15
Share Link: 