IDT72801_13 Datasheet, PDF (8/16 Pages) Integrated Device Technology – DUAL CMOS SyncFIFO

IDT72801/728211/72821/72831/72841/72851 DUAL CMOS SyncFIFO^TM
DUAL 256 x 9, DUAL 512 x 9, DUAL 1K x 9, DUAL 2K x 9, DUAL 4K x 9, DUAL 8K x 9
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
Programmable Almost–Full Flag (PAFA, PAFB) — PAFA (PAFB) will
go LOW when the amount of data in Array A (B) reaches the almost-full condition.
If no reads are performed after Reset, PAFA (PAFB) will go LOW after (256-m)
writes to the IDT72801's FIFO A (B); (512-m) writes to the IDT72811's FIFO
A (B); (1,024-m) writes to the IDT72821's FIFO A (B); (2,048-m) writes to the
IDT72831's FIFO A (B); (4,096-m) writes to the IDT72841's FIFO A (B); or
(8,192-m) writes to the IDT72851's FIFO A (B).
FFA (FFB) is synchronized with respect to the LOW-to-HIGH transition of the
Write Clock WCLKA (WCLKB). The offset “m” is defined in the Full Offset
registers.
IfthereisnoFulloffsetspecified, PAFA(PAFB)willgoLOWatFull-7words.
PAFA(PAFB) is synchronized with respect to the LOW-to-HIGH transition
of WCLKA (WCLKB).
ProgrammableAlmost–EmptyFlag(PAEA, PAEB) —PAEA(PAEB)will
go LOW when the read pointer is "n+1" locations less than the write pointer. The
offset "n" is defined in the Empty Offset registers. If no reads are performed after
Reset, PAEA (PAEB) will go HIGH after "n+1" writes to FIFO A (B).
If there is no Empty offset specified, PAEA (PAEB) will go LOW at Empty+7
words.
PAEA(PAEB) is synchronized with respect to the LOW-to-HIGH transition
of the Read Clock RCLKA (RCLKB).
Data Outputs (QA0 – QA8, QB0 – QB8 ) — QA0 - QA8 are the nine data
outputs for memory array A, QB0 - QB8 are the nine data outputs for memory
array B.
TABLE 1: STATUS FLAGS FOR A AND B FIFOS
NUMBER OF WORDS IN ARRAY A
NUMBER OF WORDS IN ARRAY B
72801
0
1 to n⁽¹⁾
(n+1) to (256-(m+1))
(256-m)⁽²⁾ to 255
72811
0
1 to n⁽¹⁾
(n+1) to (512-(m+1))
(512-m)⁽²⁾ to 511
72821
0
1 to n⁽¹⁾
(n+1) to (1,024-(m+1))
(1,024-m)⁽²⁾ to 1,023
256
512
1,024
NUMBER OF WORDS IN ARRAY A
NUMBER OF WORDS IN ARRAY B
72831
72841
0
0
1 to n⁽¹⁾
1 to n⁽¹⁾
(n+1) to (2,048-(m+1))
(n+1) to (4,096-(m+1))
(2,048-m)⁽²⁾ to 2,047
(4,096-m)⁽²⁾ to 4,095
2,048
4,096
72851
0
1 to n⁽¹⁾
(n+1) to (8,192-(m+1))
(8,192-m)⁽²⁾ to 8,191
8,192
NOTES:
1. n = Empty Offset (n = 7 default value)
2. m = Full Offset (m = 7 default value)
FFA
FFB
PAFA
PAFB
PAEA
PAEB
EFA
EFB
H
H
L
L
H
H
L
H
H
H
H
H
H
L
H
H
L
L
H
H
FFA
PAFA
PAEA
FFB
PAFB
PAEB
EFA
EFB
H
H
L
L
H
H
L
H
H
H
H
H
H
L
H
H
L
L
H
H
8
MARCH 2013