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29C516E_07 Datasheet, PDF (1/17 Pages) ATMEL Corporation – 16-Bit Flow-Through EDAC Error Detection And Correction unit | |||
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16âBit FlowâThrough EDAC
Error Detection And Correction unit
29C516E
1. Introduction
The 29C516E Atmel EDAC is a very low power
flowâthrough 16âbit 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 (16âbit
width), EDAC calculated checkword (6 or 8âbit 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
singleâbit errors and it detects all doubleâbit errors.
When the 29C516E uses 6âcheckbit, it can detect any
error on any single 4âbit memory chip. The 8âcheckâbit
option gives the additional capability to detect all errors
on any single 8âbit 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 singleâbit 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 doubleâbit 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 µPâmemory
interfacing. A flowâthrough 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 22/24âbit (16+6/16+8) memory data bus and
the two 16âbit processor data busses with a high drive
capability (â12.8 mA). The two data ports can be used to
create a dual port bus in front of memory space. The
Userâ1(2) can transfer data from/to the memory or
from/to the Userâ2(1), byâpassing the memory. During
read or write memory cycles processed by the Userâ1(2),
the Userâ2(1) have the possibility to listen the
transferred data.
2. Features
D Very Low Power CMOS
D 16âBit operation with 6 or 8 Check Bits
D Fast Error Detection : 31 ns (max.)
D Fast Error Correction : 32 ns (max.)
D Corrects all SingleâBit Errors
D Detects all DoubleâBit Errors
D Detects some MultiâBit Errors
D Detects Chip Errors (x1, x4 & x8 RAM Format)
D Correctable and Uncorrectable Error Flags
D Two User Data Buses
D User to User Transfer and Listening operation
D High Drive Capability on Buses : â12.8 mA
D TTL Compatible
D Single 5V ±10% Power Supply
D 100 Pin Multilayer Quad Flat Pack
(Flat leaded or L leaded).
Atmel Corporation
1
Rev. E (03 2007)
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