sic on a CD outdoors. People like to listen to their music with-
out interruption, even when moving around.
to resolving this problem. The result is an 鈥渦ltra single chip鈥?/div>
product that adds a memory controller function (with data com-
pression and expansion) for even better anti-shock performance
to Sony鈥檚 most powerful and functional CD digital signal-pro-
cessing LSI device.
While it goes without saying that this product will contribute to
the implementation of portable CD players for active users, this
device can also be used in CD players for car stereo systems.
s
*1
s
Memory controller functions, digital
signal processing, digital servo, DF,
D/A converter, and low-pass filter
circuits integrated on a single chip
Supports variable-speed playback
from 0.5 to 4脳 using CAV playback
mode.
Completely adjustment-free due to the
use of a digital servo system
Built-in DDBB*
1
function
DDBB: Digital Dynamic Bass Boost
s
s
High-Functionality Memory
Controller Function
CD players read out the digital signal
from the disc using a built-in pickup and
provide high-fidelity sound. However,
portable CD players often become un-
able to play back audio normally when,
for example, the user goes up or down
stairs and the mechanical shock applied
to the CD player causes the pickup to
lose focus, or the user simply walks nor-
mally and the swaying causes variations
in the rotation speed of the disc. In these
V
O
I
C
E
This LSI device can contribute to
improved anti-shock performance
by adding compression and expan-
sion functions to a conventional
anti-shock memory controller. How-
ever, what was most memorable
for us was the fact that the psycho-
logical strength of the individual
members of the team grew as much
as did the resistance to mechanical
shock provided by this LSI device
while we were under the pressures
of the design process. I expect that
this device will be used in many
portable products, and I strongly
recommend that you consider it for
your designs, too.
cases, when the signal is interrupted, the
audio data is interrupted and a sound
skipping occurs. The CD player
memory controller function is a system
that saves audio information in an ex-
ternal memory (DRAM) in expectation
of a sound skipping occurring. This
function prevents sound skipping by
replacing the audio data from the disc
with the stored audio when the disc data
is interrupted by a mechanical shock. The
CXD3027R-1 supports DRAM capaci-
ties of 4M or 16M bits, and supports
compression/expansion for handling the
stored audio data. Applications can
choose one of four modes in which data
is stored in its original 16-bit word
length, compressed to 4 bits, com-
pressed to 6 bits, or compressed to 8 bits.
If memory has been filled with data, the
CXD3027R-1 can continue providing
audio playback to the user for the fixed
periods (logical values) listed in table
1.
Digital Signal Processing
The CXD3027R-1 supports variable
playback speeds from 0.5 to 4脳. This
system provides the following advan-
tages since the anti-shock functions are
implemented for CAV playback.
鈥?Since rough servo control of the mo-
tor speed can be used with the spindle
motor, the number of acceleration and
deceleration operations is reduced.
This reduces vibration and power
consumption.
鈥?Since there is no need to change the
disc speed when jumping tracks, the
signal can be read out immediately.
This can reduce the access time.
Furthermore, since it was necessary to
integrate this memory controller
function on the same chip as the high-
functionality CD digital signal-process-
ing LSI device, we fabricated the
CXD3027R-1 in a new process technol-
ogy. This allowed power consumption
to be reduced.
On-Chip DDBB
The CXD3027R-1 provides a bass boost
function that requires no external com-
ponents by using built-in digital filters.
Note that the amount of boost can be
varied according to the input level, i.e.
to function dynamically.
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