SM5907AF Datasheet, PDF (25/30 Pages) Nippon Precision Circuits Inc – compression and non compression type shock-proof memory controller

SM5907AF
Through-mode operation
If MSON is set LOW (80H command), an operating
mode that does not perform shock-proof functions
becomes active. In this case, input data is passed
as-is (except Force mute operation) to the output.
External DRAM is not accessed.
- In this case, input data needs to be at a rate fs
and the input word clock must be synchronized to
the CLK input (384fs). However, short-range jitter
can be tolerated (jitter-free system).
- Jitter-free system timing starts from the first
YLRCK rising edge after either (A) a reset (NRE-
SET= 0) release by taking the reset input from
LOW to HIGH or (B) by taking MSON from HIGH to
LOW. Accordingly, to provide for the largest possi-
ble jitter margin, it is necessary that the YLRCK
clock be at rate fs by the time jitter-free timing
starts.
The jitter margin is 0.2/ fs (80 clock cycles).
This jitter margin is the allowable difference
between the system clock (CLK) divided by 384 (fs
rate clock) and the YLRCK input clock.
If the timing difference exceeds the jitter margin,
irregular operation like data being output twice or,
conversely, incomplete data output may occur. In
the worst case, a click noise may also be generat-
ed.
When switching from shock-proof mode to through
mode, an output noise may be generated, and it is
therefore recommended to use the YDMUTE set-
ting to mute ZSRDATA until just before data output.
Force mute
Serial output data is muted by setting the YDMUTE
pin input HIGH or by setting the MUTE flag to 1.
Mute starts and finishes on the leading left-channel
bit.
When MSON is HIGH and valid data is empty
(MSEMP=H), the output is automatically forced into
the mute state.
12-bit comparison connection
When the CMP12 flag is set to 1, the least signifi-
cant 4 bits of the 16-bit comparison connection
input data are discarded and comparison connec-
tion is performed using the remaining 12 bits.
Note that if the CMP12 flag is set to 1 during a com-
parison connection operation, only the most signifi-
cant 12 bits are used for comparison connection
from that point on.
NIPPON PRECISION CIRCUITS-25