ISDC_FAQ.PDF

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Frequently Asked Questions
ChipCorder Technology
CHIPCORDER FAQS
ChipCorder devices are microprocessor-
compatible, allowing complex messages to be
achieved. Additionally, many devices can be
directly cascaded to increase the record and
playback duration. The most frequently asked
questions are answered below:
How many times can a message be re-recorded and
how long will it be stored?
Messages can be re-recorded up to 100,000
times and can be stored up to 100 years. These
are typical numbers based on accelerated life
tests performed on ChipCorder devices.
What exactly is multilevel storage?
“Multilevel” storage is a high-density storage
methodology. Conventional digital storage, for
example, stores one “bit” of information per mem-
ory cell—a “1” or a “0” (or, in terms of voltage lev-
els, an “on” or an “off”). ChipCorder technology
improves upon this and stores up to 256 distinct
voltage levels per single cell. That is, ChipCorder
devices store up to eight times (2
8
= 256) more in-
formation in the same amount of space. Thus, for
a given quality of voice reproduction, one-
eighth the silicon storage is required over con-
ventional techniques.
How can multilevel storage technology benefit my
product design?
ChipCorder technology benefits product design
in many ways: (1) the natural sound reproduc-
tion offered creates a high-quality product im-
pression. Other solutions have often been
rejected for their artificial or “synthetic” sound
quality; (2) a single-chip solution simplifies the de-
sign process, enables extremely compact prod-
ucts and shortens time-to-market; (3) ISD’s
nonvolatile, multilevel storage ensures valuable
data is never lost; (4) multiple record cycle ca-
pability extends the life and increases the value
of your products; and (5) the high density stor-
age achieved by this patented technology facil-
itates cost-effective record and playback
products.
How are signals actually stored in the memory cells
using ChipCorder technology? How reliable is it?
ISD’s patented technology enables small pack-
ets of charge to be pulsed in a controlled man-
ner through the oxide into the floating gate in the
storage cell. Digital solutions, in comparison, drive
a tremendous amount of charge through the ox-
ide all at once, literally causing much greater
“wear and tear” on the thin gate oxide. ISD’s
storage implementation, therefore, provides
much greater reliability and a higher number of
record cycles over conventional storage devic-
es.
ISD
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Frequently Asked Questions
Increased compression techniques are being used with
digital solutions. Does this reduce ChipCorder’s
technology advantage?
Any compression or digital reduction technique
performed on digital data results in lower repro-
duction quality: the greater the compression, the
lower the quality. The superior sound quality Chip-
Corder technology provides over compressed
digital data, therefore, is quite pronounced,
even at equal sampling frequencies. Compared
to a common digital reduction technique (4-bit
ADPCM), ChipCorder devices retain a storage
density advantage (4:1, in this case).
Why have other companies not challenged ISD with
similar or competing technologies?
Although companies have tried, competitors
have not been able to emulate or duplicate
ISD’s technology. To date, ISD is the sole supplier
of this unique multilevel storage technology and
holds a powerful patent position. Additionally,
ISD’s strong engineering and R&D team contin-
ues to innovate storage techniques and en-
hance the ChipCorder product line.
I cannot get Message Cueing (MO) to work on my
ISD2500. What am I doing wrong?
The most common mistake is to send four quick
CE\ pulses and expect to be at the beginning of
message five. This doesn’t work. Send each
CE\pulse separately, wait for the EOM\pulse to
indicate the chip is ready to accept the next
CE\pulse, and THEN send that next CE\pulse.
Otherwise the CE pulses will not be counted cor-
rectly. See timing in the section on Configuration
Modes.
How do ChipCorder devices perform in lower-power,
battery-powered applications?
ChipCorder devices are ideal for handheld, bat-
tery-powered applications for four main reasons:
(1) all devices are nonvolatile and require no
battery backup; (2) a single microchip provides
the entire record/playback solution, saving both
space and power; (3) ChipCorder devices have
significantly fewer storage cells than convention-
al solutions, thereby requiring less power; and (4)
all ChipCorder solutions have been designed
with power savings in mind, thus, several of them
automatically power down at the end of every
message.
For a Chip-on-Board (COB) design, how do I connect the
backside of the die?
When attaching the ISD die to PC boards (or to
other hybrid packages) it must be remembered
that present ISD products have the substrate ma-
terial connected to V
SS
! The die attach area
CANNOT be connected to V
CC
OR have signal
lines running under the die. They will be shorted
to V
SS
through the substrate resistance and
cause early or immediate failure of the design, in
addition to high battery standby current. This is
particularly noticeable if the die attach material
is a conductive epoxy.
The die attach area must be grounded (V
SS
) or
left floating. Connecting the die attach area to
V
SS
may, in some cases, improve the noise per-
formance of the design. This is the preferred pro-
cedure that the Applications Department
suggests.
Also available on the web site:
http:/www.isd.com/products/chipcorder/
faq/index.html
What development tools does ISD offer? Can I program
ChipCorder devices with a standard message?
Although development systems are not required
with ChipCorder devices, ISD offers several eval-
uation and programming systems for sale. The
sound development and programming system
enables users to create, edit and mass-program
ISD devices with extremely accurate messages.
This comprehensive data book includes a sec-
tion entitled “Application Information,” which
depicts several complete schematics and de-
scriptions of sample applications, including mi-
crophone and speaker recommendations.
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Voice Solutions in Silicon
™

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