IDT72V3640/50/60/70/80/90/110 3.3V HIGH DENSITY SUPERSYNC II
TM
36-BIT FIFO
1,024 x 36, 2,048 x 36, 4,096 x 36, 8,192 x 36, 16,384 x 36, 32,768 x 36, 65,536 x 36, 131,072 x 36
COMMERCIAL AND INDUSTRIAL
TEMPERATURE RANGES
DESCRIPTION (CONTINUED)
of RCLK when
REN
is asserted. An Output Enable (OE) input is provided for
three-state control of the outputs.
The frequencies of both the RCLK and the WCLK signals may vary from 0
to f
MAX
with complete independence. There are no restrictions on the frequency
of the one clock input with respect to the other.
There are two possible timing modes of operation with these devices: IDT
Standard mode and First Word Fall Through (FWFT) mode.
In
IDT Standard mode,
the first word written to an empty FIFO will not appear
on the data output lines unless a specific read operation is performed. A read
operation, which consists of activating
REN
and enabling a rising RCLK edge,
will shift the word from internal memory to the data output lines.
In
FWFT mode,
the first word written to an empty FIFO is clocked directly
to the data output lines after three transitions of the RCLK signal. A
REN
does
not have to be asserted for accessing the first word. However, subsequent
words written to the FIFO do require a LOW on
REN
for access. The state of
the FWFT/SI input during Master Reset determines the timing mode in use.
For applications requiring more data storage capacity than a single FIFO
can provide, the FWFT timing mode permits depth expansion by chaining FIFOs
in series (i.e. the data outputs of one FIFO are connected to the corresponding
data inputs of the next). No external logic is required.
These FIFOs have five flag pins,
EF/OR
(Empty Flag or Output Ready),
FF/IR
(Full Flag or Input Ready),
HF
(Half-full Flag),
PAE
(Programmable
Almost-Empty flag) and
PAF
(Programmable Almost-Full flag). The
EF
and
FF
functions are selected in IDT Standard mode. The
IR
and
OR
functions are
selected in FWFT mode.
HF, PAE
and
PAF
are always available for use,
irrespective of timing mode.
PAE
and
PAF
can be programmed independently to switch at any point in
memory. Programmable offsets determine the flag switching threshold and can
be loaded by two methods: parallel or serial. Eight default offset settings are also
provided, so that
PAE
can be set to switch at a predefined number of locations
from the empty boundary and the
PAF
threshold can also be set at similar
predefined values from the full boundary. The default offset values are set during
Master Reset by the state of the FSEL0, FSEL1, and
LD
pins.
For serial programming,
SEN
together with
LD
on each rising edge of
WCLK, are used to load the offset registers via the Serial Input (SI). For parallel
programming,
WEN
together with
LD
on each rising edge of WCLK, are used
to load the offset registers via D
n
.
REN
together with
LD
on each rising edge
of RCLK can be used to read the offsets in parallel from Q
n
regardless of whether
serial or parallel offset loading has been selected.
During Master Reset (MRS) the following events occur: the read and write
pointers are set to the first location of the FIFO. The FWFT pin selects IDT
Standard mode or FWFT mode.
The Partial Reset (PRS) also sets the read and write pointers to the first
location of the memory. However, the timing mode, programmable flag
programming method, and default or programmed offset settings existing before
Partial Reset remain unchanged. The flags are updated according to the timing
mode and offsets in effect.
PRS
is useful for resetting a device in mid-operation,
when reprogramming programmable flags would be undesirable.
It is also possible to select the timing mode of the
PAE
(Programmable Almost-
Empty flag) and
PAF
(Programmable Almost-Full flag) outputs. The timing
modes can be set to be either asynchronous or synchronous for the
PAE
and
PAF
flags.
If asynchronous
PAE/PAF
configuration is selected, the
PAE
is asserted
LOW on the LOW-to-HIGH transition of RCLK.
PAE
is reset to HIGH on the LOW-
to-HIGH transition of WCLK. Similarly, the
PAF
is asserted LOW on the LOW-
to-HIGH transition of WCLK and
PAF
is reset to HIGH on the LOW-to-HIGH
transition of RCLK.
If synchronous
PAE/PAF
configuration is selected , the
PAE
is asserted and
updated on the rising edge of RCLK only and not WCLK. Similarly,
PAF
is
PARTIAL RESET (PRS)
WRITE CLOCK (WCLK)
WRITE ENABLE (WEN)
LOAD (LD)
(x36, x18, x9) DATA IN (D
0
- D
n
)
SERIAL ENABLE(SEN)
FIRST WORD FALL THROUGH/SERIAL INPUT
(FWFT/SI)
FULL FLAG/INPUT READY (FF/IR)
PROGRAMMABLE ALMOST-FULL (PAF)
MASTER RESET (MRS)
READ CLOCK (RCLK)
READ ENABLE (REN)
IDT
72V3640
72V3650
72V3660
72V3670
72V3680
72V3690
72V36100
72V36110
OUTPUT ENABLE (OE)
(x36, x18, x9) DATA OUT (Q
0
- Q
n
)
RETRANSMIT (RT)
EMPTY FLAG/OUTPUT READY (EF/OR)
PROGRAMMABLE ALMOST-EMPTY (PAE)
HALF-FULL FLAG (HF)
BIG-ENDIAN/LITTLE-ENDIAN (BE)
INTERSPERSED/
NON-INTERSPERSED PARITY (IP)
4667 drw 03
INPUT WIDTH (IW)
OUTPUT WIDTH (OW)
BUS-
MATCHING
(BM)
Figure 1. Single Device Configuration Signal Flow Diagram
3
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