idt49c465apqfb Integrated Device Technology, idt49c465apqfb Datasheet - Page 6

• Manufacturer Part Number: idt49c465apqfb
• Description: 32-bit Flow-thru Error Detection Correction Unit
• Manufacturer: Integrated Device Technology

IDT49C465/A
32-BIT FLOW-THRU ERROR DETECTION AND CORRECTION UNIT
FUNCTIONAL DESCRIPTION
The error detection/correction codes consist of a modified
Hamming code; it is identical to that used in the IDT49C460.
32-BIT MODE (CODE ID 1,0=00)
64-BIT MODE (CODE ID 1,0=10 & 11)
topology allows the syndrome bits used by the correction logic
to be generated simultaneously in both parts used in the
expansion. During a 64-bit detection or correction operation,
CHECKBITS–IN
64-BIT GENERATE-ONLY MODE (CODE ID 1,0=01)
in the 64-bit “Generate-only” mode. In this mode, the lower 32
bits of the 64-bit data word enter the device on the MD
inputs and the upper 32-bits of the 64 bit data word enter the
The expansion bus topology is shown in Figure 6. This
If the Identity pins CODE ID 1,0 = 01, a single EDC is placed
LOWER 32 BITS (0–31)
UPPER 32 BITS (32–63)
8
(CODE ID 1,0 = 10)
PCBI
CBI
LOWER EDC
CHECKBITS–IN
V
CC
CBO
SYO
Figure 6. 64-Bit Mode — 2 Cascaded IDT49C465 Devices
8
8
8
Figure 7. 64-Bit "Generate-Only" Mode (Single Chip)
32
32
PARTIAL–CHECKBITS–OUT (11)
(CORRECTION ONLY)
PARTIAL–CHECKBITS–OUT (10)
PARTIAL–CHECKBITS–OUT (10)
(GENERATE ONLY)
(GENERATE ONLY)
PARTIAL–SYNDROME
(DETECT/CORRECT ONLY)
8
7
PCBI
CBI
CBI
Figure 5. 32-Bit Mode
7
0–6
0-31
EDC
MD
SD
11.7
0–31
0–31
“Partial-Checkbit” data and “Partial-Syndrome” data is simul-
taneously exchanged between the two EDC units in opposite
directions on dedicated expansion buses. This results in very
short 64-bit detection and correction times.
device on the SD
full 64-bit word from memory.
checkbits are output on the CBO
time is less than that resulting from using a 2-chip cascade.
CBO
SYO
EDC
7
7
MILITARY AND COMMERCIAL TEMPERATURE RANGES
CHECKBITS–OUT
SYNDROME–OUT
CBO
(CODE ID 1,0 = 11)
PCBI
CBI
UPPER EDC
0-31
2552 drw 09
inputs. This provides the device with the
8
CBO
SYO
ERR
0-7
8
(DETECT AND CORRECT)
The resultant generated
CHECKBITS–OUT
outputs. The generate
FINAL
CHECKBITS–OUT
2552 drw 11
2552 drw 10
6