29C516E
16–Bit Flow–Through EDAC
Error Detection And Correction unit
1. Introduction
The 29C516E
Atmel
EDAC is a very low power
flow–through 16–bit Error Detection And Correction unit
(EDAC) with two user data buses. The EDAC is used in
a high integrity system for monitoring and correction of
data values coming from the memory space. During a
processor write cycle, at each memory location (16–bit
width), EDAC calculated checkword (6 or 8–bit width) is
added. When performing a read operation from memory,
the 29C516E verifies the entire checkword and data
combination. It detects and can correct 100% of all the
single–bit errors and it detects all double–bit errors.
When the 29C516E uses 6–checkbit, it can detect any
error on any single 4–bit memory chip. The 8–check–bit
option gives the additional capability to detect all errors
on any single 8–bit memory chip. All the errors are
signaled to the master system (via 2 error Flags) in order
to allow the processor to make the required action.
The 29C516E operates in two possible modes: corrected
or detected mode. In the corrected mode, the single–bit in
error is complemented (corrected). Then, the available
entire data is placed on the output port and the Correctable
Error Flag is set. In case of double–bit errors (or more),
the corrupted data is placed on the output port and the
Uncorrectable Error Flag is set. Note that when there is
more than two errors, then some bit patterns may appear
as possible correctable errors. Therefore, if the
environment produces this type of error, the EDAC must
be used in detect and provide no automatic correction.
Data and syndrome analysis must be done.
The 29C516E acts as a data buffer for
µP–memory
interfacing. A flow–through EDAC is placed in the data
bus path, between the processor and the memory to be
protected. This component is able to serve two different
users of one memory space. So, it forms the interface
between the 22/24–bit (16+6/16+8) memory data bus and
the two 16–bit processor data busses with a high drive
capability (–12.8 mA). The two data ports can be used to
create a dual port bus in front of memory space. The
User–1(2) can transfer data from/to the memory or
from/to the User–2(1), by–passing the memory. During
read or write memory cycles processed by the User–1(2),
the User–2(1) have the possibility to listen the
transferred data.
2. Features
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Very Low Power CMOS
16–Bit operation with 6 or 8 Check Bits
Fast Error Detection : 31 ns (max.)
Fast Error Correction : 32 ns (max.)
Corrects all Single–Bit Errors
Detects all Double–Bit Errors
Detects some Multi–Bit Errors
Detects Chip Errors (x1, x4 & x8 RAM Format)
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Correctable and Uncorrectable Error Flags
Two User Data Buses
User to User Transfer and Listening operation
High Drive Capability on Buses : –12.8 mA
TTL Compatible
Single 5V
±10%
Power Supply
100 Pin Multilayer Quad Flat Pack
(Flat leaded or L leaded).
Atmel Corporation
Rev.
E
(03
2007)
1
ATMEL [ ATMEL CORPORATION ]
