Datasheet IDT72V2101, IDT72V2111 Datasheet (IDT)

查询IDT72V2101供应商

3.3 VOLT HIGH DENSITY CMOS
SUPERSYNC FIFO™
262,144 x 9
524,288 x 9

FEATURES:

••

• Choose among the following memory organizations:

••

IDT72V2101
IDT72V2111

•

Pin-compatible with the IDT72V261/72V271 and the IDT72V281/
72V291 SuperSync FIFOs

• 10ns read/write cycle time (6.5ns access time)

• Fixed, low first word data latency time

• 5V input tolerant

• Auto power down minimizes standby power consumption

• Master Reset clears entire FIFO

• Partial Reset clears data, but retains programmable settings

• Retransmit operation with fixed, low first word data latency time

• Empty, Full and Half-Full flags signal FIFO status

• Programmable Almost-Empty and Almost-Full flags, each flag can

default to one of two preselected offsets

• Program partial flags by either serial or parallel means

• Select IDT Standard timing (using EF and FF flags) or First Word Fall

Through timing (using OR and IR flags)

•

Output enable puts data outputs into high impedance state

• Easily expandable in depth and width

• Independent Read and Write clocks (permit reading and writing



 262,144 x 9




 524,288 x 9



IDT72V2101

IDT72V2111

simultaneously)

• Available in the 64-pin Thin Quad Flat Pack (TQFP)

• High-performance submicron CMOS technology

DESCRIPTION:

The IDT72V2101/72V2111 are exceptionally deep, high speed, CMOS
First-In-First-Out (FIFO) memories with clocked read and write controls. These
FIFOs offer numerous improvements over previous SuperSync FIFOs,
including the following:

• The limitation of the frequency of one clock input with respect to the other has

been removed. The Frequency Select pin (FS) has been removed, thus

it is no longer necessary to select which of the two clock inputs, RCLK or

WCLK, is running at the higher frequency.

• The period required by the retransmit operation is now fixed and short.

• The first word data latency period, from the time the first word is written to an

empty FIFO to the time it can be read, is now fixed and short. (The variable

clock cycle counting delay associated with the latency period found on

previous SuperSync devices has been eliminated on this SuperSync family.)
SuperSync FIFOs are particularly appropriate for network, video, telecommu­nications, data communications and other applications that need to buffer large
amounts of data.

FUNCTIONAL BLOCK DIAGRAM

WEN

WCLK

WRITE CONTROL

LOGIC

WRITE POINTER

OUTPUT REGISTER

MRS

PRS

RESET

LOGIC

0

-D

8

D

INPUT REGISTER

RAM ARRAY

262,144 x 9
524,288 x 9

LD

OFFSET REGISTER

FLAG

LOGIC

READ POINTER

READ

CONTROL

LOGIC

SEN

FF/IR
PAF
EF/OR
PAE
HF

FWFT/SI

RT

RCLK

REN

0

-Q

8

OE

The SuperSync FIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc.

COMMERCIAL AND INDUSTRIAL TEMPERATURE RANGES



2001 Integrated Device Technology, Inc.

Q

4669 drw 01

MARCH 2001

DSC-4669/2

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

DESCRIPTION (CONTINUED)

The input port is controlled by a Write Clock (WCLK) input and a Write Enable
(WEN) input. Data is written into the FIFO on every rising edge of WCLK when
WEN is asserted. The output port is controlled by a Read Clock (RCLK) input
and Read Enable (REN) input. Data is read from the FIFO on every rising edge
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.

PIN CONFIGURATIONS

FWFT/SI

WCLK

PRS

MRS

LD

GND

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.

CC

PAF

HF

V

EF/OR

PAE

RCLK

REN

OE

RT

FF/IR

PIN 1

WEN

SEN

DC

V

V
GND
GND
GND
GND
GND
GND
GND
GND
GND

CC
CC

D8
D7

64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49

(3)

1
2

(1)

3
4
5

(2)

(2)

(2)

(2)

(2)

(2)

(2)

(2)

(2)

6
7
8
9
10
11
12
13
14
15
16

48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33

DNC
DNC
GND
DNC
DNC
V

CC

DNC
DNC
DNC
GND
DNC
DNC
Q8
Q7
Q6
GND

(3)

(3)

(3)

(3)

(3)

(3)

(3)

(3)

17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

NOTES:

1. DC = Don’t Care. Must be tied to GND or V

2. This pin may either be tied to ground or left open.

3. DNC = Do Not Connect.

CC, cannot be left open.

D6

D5

D4

D3

D2

D1

GND

D0

TQFP (PN64-1, order code: PF)

TOP VIEW

2

Q0

Q1

GND

Q2

Q3

CC

V

Q4

Q5

4669 drw 02

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

PAE and PAF can be programmed independently to switch at any point in
memory. (See Table I and Table II.) Programmable offsets determine the flag
switching threshold and can be loaded by two methods: parallel or serial. Two
default offset settings are also provided, so that PAE can be set to switch at 127
or 1,023 locations from the empty boundary and the PAF threshold can be set
at 127 or 1,023 locations from the full boundary. These choices are made with
the LD pin during Master Reset.

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 Qn
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 LD pin selects either a partial flag default
setting of 127 with parallel programming or a partial flag default setting of 1,023

with serial programming. The flags are updated according to the timing mode
and default offsets selected.

The Partial Reset (PRS) also sets the read and write pointers to the first
location of the memory. However, the timing mode, partial 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 mid­operation, when reprogramming partial flags would be undesirable.

The Retransmit function allows data to be reread from the FIFO. A LOW
on the RT input during a rising RCLK edge initiates a retransmit operation
by setting the read pointer to the first location of the memory array.

If, at any time, the FIFO is not actively performing an operation, the chip will
automatically power down. Once in the power down state, the standby supply
current consumption is minimized. Initiating any operation (by activating control
inputs) will immediately take the device out of the power down state.

The IDT72V2101/72V2111 are fabricated using IDT’s high speed submi­cron CMOS technology.

PARTIAL RESET (PRS)

WRITE CLOCK (WCLK)

WRITE ENABLE (WEN)

LOAD (LD)

0

DATA IN (D

- Dn)

SERIAL ENABLE(SEN)

FIRST WORD FALL THROUGH/SERIAL INPUT

(FWFT/SI)

FULL FLAG/INPUT READY (FF/IR)

PROGRAMMABLE ALMOST-FULL (PAF)

Figure 1. Block Diagram of Single 262,144 x 9 and 524,288 x 9 Synchronous FIFO

MASTER RESET (MRS)

READ CLOCK (RCLK)
READ ENABLE (REN)

OUTPUT ENABLE (OE)
DATA OUT (Q0 - Qn)

IDT
72V2101
72V2111

RETRANSMIT (RT)
EMPTY FLAG/OUTPUT READY (EF/OR)
PROGRAMMABLE ALMOST-EMPTY (PAE)

HALF FULL FLAG (HF)

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3

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

PIN DESCRIPTION

Symbol Name I/O Description

0–D8 Data Inputs I Data inputs for a 9-bit bus.

D
MRS Master Reset I MRS initializes the read and write pointers to zero and sets the output register to

all zeroes. During Master Reset, the FIFO is configured for either FWFT or IDT
Standard mode, one of two programmable flag default settings, and serial or
parallel programming of the offset settings.

PRS Partial Reset I PRS initializes the read and write pointers to zero and sets the output register to

all zeroes. During Partial Reset, the existing mode (IDT or FWFT), programming
method (serial or parallel), and programmable flag settings are all retained.

RT Retransmit I RT asserted on the rising edge of RCLK initializes the READ pointer to zero, sets

the EF flag to LOW (OR to HIGH in FWFT mode) temporarily and does not disturb
the write pointer, programming method, existing timing mode or programmable flag
settings. RT is useful to reread data from the first physical location of the FIFO.

FWFT/SI First Word Fall I During Master Reset, selects First Word Fall Through or IDT Standard mode.

Through/Serial In After Master Reset, this pin functions as a serial input for loading offset registers

WCLK Write Clock I When enabled by WEN, the rising edge of WCLK writes data into the FIFO and

offsets into the programmable registers for parallel programming, and when
enabled by SEN, the rising edge of WCLK writes one bit of data into the

programmable register for serial programming.
WEN Write Enable I WEN enables WCLK for writing data into the FIFO memory and offset registers.
RCLK Read Clock I When enabled by REN, the rising edge of RCLK reads data from the FIFO

memory and offsets from the programmable registers.

REN Read Enable I REN enables RCLK for reading data from the FIFO memory and offset registers.
OE Output Enable I OE controls the output impedance of Q
SEN Serial Enable I SEN enables serial loading of programmable flag offsets.
LD Load I During Master Reset, LD selects one of two partial flag default offsets (127 or

1,023) and determines the flag offset programming method, serial or parallel. After

Master Reset, this pin enables writing to and reading from the offset registers.
DC Don't Care I This pin must be tied to either V

Reset.
FF/IR Full Flag/ O In the IDT Standard mode, the FF function is selected. FF indicates whether or

Input Ready not the FIFO memory is full. In the FWFT mode, the IR function is selected. IR

indicates whether or not there is space available for writing to the FIFO memory.
EF/OR Empty Flag/ O In the IDT Standard mode, the EF function is selected. EF indicates whether or

Output Ready not the FIFO memory is empty. In FWFT mode, the OR function is selected.

OR indicates whether or not there is valid data available at the outputs.
PAF Programmable O PAF goes LOW if the number of words in the FIFO memory is more than

Almost-Full Flag total word capacity of the FIFO minus the full offset value m, which is stored in the

Full Offset register. There are two possible default values for m: 127 or 1,023.
PAE Programmable O PAE goes LOW if the number of words in the FIFO memory is less than offset n,

Almost-Empty Flag which is stored in the Empty Offset register. There are two possible default values

for n: 127 or 1,023. Other values for n can be programmed into the device.
HF Half-Full Flag O HF indicates whether the FIFO memory is more or less than half-full.
Q

0–Q8 Data Outputs O Data outputs for a 9-bus

V

CC Power +3.3 Volt power supply pins.

GND Ground Ground pins.

n.

CC or GND and must not toggle after Master

4

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

ABSOLUTE MAXIMUM RATINGS

Symbol Rating Com’l & Ind’l Unit

(2)

TERM

V

T

STG Storage –55 to +125 °C

OUT DC Output Current –50 to +50 mA

I

NOTES:

1. Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause
permanent damage to the device. This is a stress rating only and functional operation
of the device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect reliability.

CC terminal only.

2. V

Terminal Voltage –0.5 to +4.5 V
with respect to GND

Temperature

RECOMMENDED DC OPERATING
CONDITIONS

Symbol Parameter Min. Typ. Max. Unit

(1)

V

CC

Supply Voltage (Com'l & Ind'l) 3.15 3.3 3.45 V

GND Supply Voltage (Com'l & Ind'l) 0 0 0 V

IH Input High Voltage (Com'l & Ind'l) 2.0 — 5.5 V

V

(2)

IL

Input Low Voltage (Com'l & Ind'l) — — 0.8 V

V

A Operating Temperature Commercial 0 — +70 ° C

T

A Operating Temperature Industrial - 40 — +85 °C

T

NOTES:

CC = 3.3V ± 0.15V, JEDEC JESD8-A compliant.

1. V

2. 1.5V undershoots are allowed for 10ns once per cycle.

DC ELECTRICAL CHARACTERISTICS

(Commercial: VCC = 3.3V ± 0.15V, TA = 0°C to +70°C; Industrial: VCC = 3.3V ± 0.15V, TA = -40°C to +85°C; JEDEC JESD8-A compliant)

IDT72V2101L
IDT72V2111L

Commercial and Industrial

tCLK = 10, 15, 20 ns

Symbol Parameter Min. Max. Unit

(2)

I

LI

(3)

LO

I
V

OH Output Logic “1” Voltage, IOH = –2 mA 2.4 — V
OL Output Logic “0” Voltage, IOL = 8 mA — 0.4 V

V

(4,5,6)

I

CC1

(4,7)

CC2

I

NOTES:

1. Industrial temperature range product for the 15ns speed grade is available as a standard device.

2. Measurements with 0.4 ≤ V

3. OE

≥ VIH, 0.4 ≤ VOUT ≤ VCC.

4. Tested with outputs open (IOUT = 0).

5. RCLK and WCLK toggle at 20 MHz and data inputs switch at 10 MHz.

6. Typical I

L = capacitive load (in pF).

C

7. All Inputs = V

Input Leakage Current –1 1 µA
Output Leakage Current –1 0 10 µA

Active Power Supply Current — 5 5 mA
Standby Current — 20 mA

IN ≤ VCC.

CC1 = XX + XX*fS + 0.02*CL*fS (in mA) with VCC = 3.3V, tA = 25°C, fS = WCLK frequency = RCLK frequency (in MHz, using TTL levels), data switching at fS/2,

CC - 0.2V or GND + 0.2V, except RCLK and WCLK, which toggle at 20 MHz.

(1)

CAPACITANCE (TA = +25°C, f = 1.0MHz)

Symbol Parameter

(2)

IN

C

Input VIN = 0V 10 pF
Capacitance

(1,2)

C

OUT

Output VOUT = 0V 10 pF
Capacitance

NOTES:

1. With output deselected, (OE ≥ V

2. Characterized values, not currently tested.

(1)

Conditions Max. Unit

IH).

5

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

AC ELECTRICAL CHARACTERISTICS

(1)

(Commercial: VCC = 3.3V ± 0.15V, TA = 0°C to +70°C; Industrial: VCC = 3.3V ± 0.15V, TA = -40°C to +85°C; JEDEC JESD8-A compliant)

Commercial Com’l & Ind’l
IDT72V2101L10 IDT72V2101L15 IDT72V2101L20
IDT72V2111L10 IDT72V2111L15 IDT72V2111L20

Symbol Parameter Min. Max. Min. Max. Min. Max. Unit

S Clock Cycle Frequency — 100 — 66.7 — 50 MHz

f

A Data Access Time 2 6.5 2 1 0 2 12 ns

t

CLK Clock Cycle Time 10 — 15 — 20 — ns

t

CLKH Clock High Time 4.5 — 6 — 8 — ns

t

CLKL Clock Low Time 4.5 — 6 — 8 — ns

t

DS Data Setup Time 3 — 4 — 5 — ns

t

DH Data Hold Time 0.5 — 1 — 1 — ns

t

ENS Enable Setup Time 3 — 4 — 5 — ns

t

ENH Enable Hold Time 0. 5 — 1 — 1 — ns

t

LDS Load Setup Time 3 — 4 — 5 — ns

t

LDH Load Hold Time 0 .5 — 1 — 1 — n s

t

RS Reset Pulse Width

t

RSS Reset Setup Time 1 5 — 15 — 20 — ns

t

RSR Reset Recovery Time 1 0 — 15 — 2 0 — ns

t

RSF Reset to Flag and Output Time — 10 — 1 5 — 20 ns

t

FWFT Mode Select Time 0 — 0 — 0 — n s

t

RTS Retransmit Setup Time 3 — 4 — 5 — ns

t

OLZ Output Enable to Output in Low Z

t

OE Output Enable to Output Valid 2 6 2 8 2 10 ns

t

OHZ Output Enable to Output in High Z

t

WFF Write Clock to FF or IR — 6.5 — 10 — 12 ns

t

REF Read Clock to EF or OR — 6.5 — 10 — 12 ns

t

PAF Write Clock to PAF — 6.5 — 10 — 12 ns

t

PAE Read Clock to PAE — 6.5 — 10 — 12 ns

t

HF Clock to HF —16—20—22ns

t

SKEW1 Skew time between RCLK and WCLK 8 — 9 — 10 — n s

t

(3)

(4)

(4)

10 — 15 — 20 — ns

0—0—0—ns

2628210ns

for EF/OR and FF/IR

SKEW2 Skew time between RCLK and WCLK 12 — 14 — 15 — ns

t

for PAE and PAF

NOTES:

1. Industrial temperature range product for the 15ns speed grade is available as a standard device.

2. All AC timings apply to both Standard IDT mode and First Word Fall Through mode.

3. Pulse widths less than minimum values are not allowed.

4. Values guaranteed by design, not currently tested.

(1)

Commercial

3.3V

330Ω

AC TEST CONDITIONS

Input Pulse Levels GND to 3.0V
Input Rise/Fall Times 3ns
Input Timing Reference Levels 1.5V
Output Reference Levels 1.5V
Output Load See Figure 2

D.U.T.

510Ω

30pF*

4669 drw 04

Figure 2. Output Load

* Includes jig and scope capacitances.

6

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

FUNCTIONAL DESCRIPTION

TIMING MODES: IDT STANDARD vs FIRST WORD FALL THROUGH
(FWFT) MODE

The IDT72V2101/72V2111 support two different timing modes of operation:
IDT Standard mode or First Word Fall Through (FWFT) mode. The selection
of which mode will operate is determined during Master Reset, by the state of
the FWFT/SI input.

If, at the time of Master Reset, FWFT/SI is LOW, then IDT Standard mode
will be selected. This mode uses the Empty Flag (EF) to indicate whether or
not there are any words present in the FIFO. It also uses the Full Flag function
(FF) to indicate whether or not the FIFO has any free space for writing. In IDT
Standard mode, every word read from the FIFO, including the first, must be
requested using the Read Enable (REN) and RCLK.

If, at the time of Master Reset, FWFT/SI is HIGH, then FWFT mode will
be selected. This mode uses Output Ready (OR) to indicate whether or not
there is valid data at the data outputs (Q
indicate whether or not the FIFO has any free space for writing. In the FWFT
mode, the first word written to an empty FIFO goes directly to Qn after three
RCLK rising edges, REN = LOW is not necessary. Subsequent words must
be accessed using the Read Enable (REN) and RCLK.

Various signals, both input and output signals operate differently de-

pending on which timing mode is in effect.

IDT STANDARD MODE

In this mode, the status flags, FF, PAF, HF, PAE, and EF operate in the
manner outlined in Table 1. To write data into to the FIFO, Write Enable (WEN)
must be LOW. Data presented to the DATA IN lines will be clocked into the FIFO
on subsequent transitions of the Write Clock (WCLK). After the first write is
performed, the Empty Flag (EF) will go HIGH. Subsequent writes will continue
to fill up the FIFO. The Programmable Almost-Empty flag (PAE) will go HIGH
after n + 1 words have been loaded into the FIFO, where n is the empty offset
value. The default setting for this value is stated in the footnote of Table 1. This
parameter is also user programmable. See section on Programmable Flag
Offset Loading.

If one continued to write data into the FIFO, and we assumed no read
operations were taking place, the Half-Full flag (HF) would toggle to LOW
once the 131,073th word for IDT72V2101 and 262,145th word for
IDT72V2111 respectively was written into the FIFO. Continuing to write
data into the FIFO will cause the Programmable Almost-Full flag (PAF) to
go LOW. Again, if no reads are performed, the PAF will go LOW after
(262,144-m) writes for the IDT72V2101 and (524,288-m) writes for the
IDT72V2111. The offset “m” is the full offset value. The default setting for
this value is stated in the footnote of Table 1. This parameter is also user
programmable. See section on Programmable Flag Offset Loading.

When the FIFO is full, the Full Flag (FF) will go LOW, inhibiting further
write operations. If no reads are performed after a reset, FF will go LOW
after D writes to the FIFO. D = 262,144 writes for the IDT72V2101 and 524,288
for the IDT72V2111, respectively.

n). It also uses Input Ready (IR) to

If the FIFO is full, the first read operation will cause FF to go HIGH.
Subsequent read operations will cause PAF and HF to go HIGH at the conditions
described in Table 1. If further read operations occur, without write operations,
PAE will go LOW when there are n words in the FIFO, where n is the empty
offset value. Continuing read operations will cause the FIFO to become empty.
When the last word has been read from the FIFO, the EF will go LOW inhibiting
further read operations. REN is ignored when the FIFO is empty.

When configured in IDT Standard mode, the EF and FF outputs are double
register-buffered outputs.

Relevant timing diagrams for IDT Standard mode can be found in Figure
7, 8 and 11.

FIRST WORD FALL THROUGH MODE (FWFT)

In this mode, the status flags, IR, PAF, HF, PAE, and OR operate in the
manner outlined in Table 2. To write data into to the FIFO, WEN must be
LOW. Data presented to the DATA IN lines will be clocked into the FIFO on
subsequent transitions of WCLK. After the first write is performed, the
Output Ready (OR) flag will go LOW. Subsequent writes will continue to fill
up the FIFO. PAE will go HIGH after n + 2 words have been loaded into the
FIFO, where n is the empty offset value. The default setting for this value
is stated in the footnote of Table 2. This parameter is also user program­mable. See section on Programmable Flag Offset Loading.

If one continued to write data into the FIFO, and we assumed no read
operations were taking place, the HF would toggle to LOW once the
131,074th word for the IDT72V2101 and 262,146th word for the IDT72V2111,
respectively was written into the FIFO. Continuing to write data into the
FIFO will cause the PAF to go LOW. Again, if no reads are performed, the
PAF will go LOW after (262,145-m) writes for the IDT72V2101 and
(524,289-m) writes for the IDT72V2111, where m is the full offset value. The
default setting for this value is stated in the footnote of Table 2.

When the FIFO is full, the Input Ready (IR) flag will go HIGH, inhibiting
further write operations. If no reads are performed after a reset, IR will go HIGH
after D writes to the FIFO. D = 262,145 writes for the IDT72V2101 and 524,289
writes for the IDT72V2111, respectively. Note that the additional word in FWFT
mode is due to the capacity of the memory plus output register.

If the FIFO is full, the first read operation will cause the IR flag to go LOW.
Subsequent read operations will cause the PAF and HF to go HIGH at the
conditions described in Table 2. If further read operations occur, without
write operations, the PAE will go LOW when there are n + 1 words in the
FIFO, where n is the empty offset value. Continuing read operations will
cause the FIFO to become empty. When the last word has been read from
the FIFO, OR will go HIGH inhibiting further read operations. REN is ignored
when the FIFO is empty.

When configured in FWFT mode, the OR flag output is triple register­buffered, and the IR flag output is double register-buffered.

Relevant timing diagrams for FWFT mode can be found in Figure 9, 10
and 12.

7

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

PROGRAMMING FLAG OFFSETS

Full and Empty Flag offset values are user programmable. The IDT72V2101/
72V2111 has internal registers for these offsets. Default settings are stated in the
footnotes of Table 1 and Table 2. Offset values can be programmed into the FIFO
in one of two ways; serial or parallel loading method. The selection of the loading
method is done using the LD (Load) pin. During Master Reset, the state of the
LD input determines whether serial or parallel flag offset programming is
enabled. A HIGH on LD during Master Reset selects serial loading of offset
values and in addition, sets a default PAE offset value of 3FFH (a threshold 1,023
words from the empty boundary), and a default PAF offset value of 3FFH (a
threshold 1,023 words from the full boundary). A LOW on LD during Master

offset value of 07FH (a threshold 127 words from the empty boundary), and
a default PAF offset value of 07FH (a threshold 127 words from the full
boundary). See Figure 3, Offset Register Location and Default Values.

In addition to loading offset values into the FIFO, it also possible to read the

current offset values. It is only possible to read offset values via parallel read.

Figure 4, Programmable Flag Offset Programming Sequence, summa­rizes the control pins and sequence for both serial and parallel programming
modes. For a more detailed description, see discussion that follows.

The offset registers may be programmed (and reprogrammed) any time
after Master Reset, regardless of whether serial or parallel programming
has been selected.

Reset selects parallel loading of offset values, and in addition, sets a default PAE

TABLE I  STATUS FLAGS FOR IDT STANDARD MODE

IDT72V2101 IDT72V2111

Number of
Words in
FIFO

0

(1)

1 to n

(n+1) to 131,072

131,073 to (262,144-(m+1))

(2)

(262,144-m)

to 262,143

262,144

262,145 to (524,288-(m+1))

(524,288-m)

0

1 to n

(n+1) to 262,144

(2)

524,288

(1)

to 524,287

FF PAF HF PAE EF

HHHL L
HHHLH
HHHHH
HHLHH

HLLHH

LLLHH

NOTES:

1. n = Empty Offset, Default Values: n = 127 when parallel offset loading is selected or n = 1,023 when serial offset loading is selected.

2. m = Full Offset, Default Values: m = 127 when parallel offset loading is selected or m = 1,023 when serial offset loading is selected.

TABLE II  STATUS FLAGS FOR FWFT MODE

IDT72V2101 IDT72V2111

0

(1)

to 262,144

(2)

262,146 to (524,289-(m+1))

(524,289-m)

Number of
Words in
FIFO

1 to n+1

(n+2) to 131,073

131,074 to (262,145-(m+1))

(262,145-m)

262,145

NOTES:

1. n = Empty Offset, Default Values: n = 127 when parallel offset loading is selected or n = 1,023 when serial offset loading is selected.

2. m = Full Offset, Default Values: m = 127 when parallel offset loading is selected or m = 1,023 when serial offset loading is selected.

0

1 to n+1

(1)

(n+2) to 262,145

to 524,288

524,289

(2)

IR PAF HF PAE OR

LHHLH
LHHLL

LHHHL
LHLHL
LLLHL
HLL HL

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IDT72V2101 (262,144 x 9BIT)

87 0

EMPTY OFFSET (LSB) REGISTER

DEFAULT VALUE

7FH if LD is LOW at Master Reset

FFH if LD is HIGH at Master Reset

87 0

EMPTY OFFSET (MID-BYTE) REGISTER

DEFAULT VALUE

00H if LD is LOW at Master Reset

03H if LD is HIGH at Master Reset

821

EMPTY OFFSET

(MSB) REGISTER

DEFAULT

0H

7

8

FULL OFFSET (LSB) REGISTER

DEFAULT VALUE

7FH if LD is LOW at Master Reset

FFH if LD is HIGH at Master Reset

0

83

0

IDT72V2111 (524,288 x 9BIT)

87 0

EMPTY OFFSET (LSB) REGISTER

DEFAULT VALUE

7FH if LD is LOW at Master Reset

FFH if LD is HIGH at Master Reset

87 0

EMPTY OFFSET (MID-BYTE) REGISTER

DEFAULT VALUE

00H if LD is LOW at Master Reset

03H if LD is HIGH at Master Reset

2

EMPTY OFFSET

(MSB) REGISTER

DEFAULT

0H

87 0

FULL OFFSET (LSB) REGISTER

DEFAULT VALUE

7FH if LD is LOW at Master Reset

FFH if LD is HIGH at Master Reset

0

87

FULL OFFSET (MID-BYTE) REGISTER

DEFAULT VALUE

00H if LD is LOW at Master Reset

03H if LD is HIGH at Master Reset

821

FULL OFFSET

(MSB) REGISTER

DEFAULT

0H

0

0

8

Figure 3. Offset Register Location and Default Values

7

8

FULL OFFSET (MID-BYTE) REGISTER

DEFAULT VALUE
00H if LD is LOW at Master Reset
03H if LD is HIGH at Master Reset

0

302

FULL OFFSET

(MSB) REGISTER

DEFAULT

0H

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LD

WEN

REN

SEN

WCLK RCLK

IDT72V2101
IDT72V2111

Parallel write to registers:

1

0

0

1

X

Empty Offset (LSB)
Empty Offset (Mid-Byte)
Empty Offset (MSB)
Full Offset (LSB)
Full Offset (Mid-Byte)
Full Offset (MSB)

Parallel read from registers:

0

1

0

1

X

Empty Offset (LSB)
Empty Offset (Mid-Byte)
Empty Offset (MSB)
Full Offset (LSB)
Full Offset (Mid-Byte)
Full Offset (MSB)

1

1

0

0

X

Serial shift into registers:
36 bits for the 72V2101
38 bits for the 72V2111
1 bit for each rising WCLK edge
Starting with Empty Offset (LSB)
Ending with FUll Offset (MSB)

1

1

X

X

0

1

1
X

XX

X

No Operation

Write Memory

0

X

1

1

1

1

NOTES:

1. The programming method can only be selected at Master Reset.

2. Parallel reading of the offset registers is always permitted regardless of which programming method has been selected.

3. The programming sequence applies to both IDT Standard and FWFT modes.

X

X

Figure 4. Programmable Flag Offset Programming Sequence

X

XX

Read Memory

No Operation

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SERIAL PROGRAMMING MODE

If Serial Programming mode has been selected, as des

cribed above, then
programming of PAE and PAF values can be achieved by using a
combination of the LD, SEN, WCLK and SI input pins. Programming PAE
and PAF proceeds as follows: when LD and SEN are set LOW, data on the
SI input are written, one bit for each WCLK rising edge, starting with the
Empty Offset LSB and ending with the Full Offset MSB. A total of 36 bits
for the IDT72V2101 and 38 bits for the IDT72V2111. See Figure 13, Serial
Loading of Programmable Flag Registers, for the timing diagram for this
mode.

Using the serial method, individual registers cannot be programmed
selectively. PAE and PAF can show a valid status only after the complete
set of bits (for all offset registers) has been entered. The registers can be
reprogrammed as long as the complete set of new offset bits is entered.
When LD is LOW and SEN is HIGH, no serial write to the registers can
occur.

Write operations to the FIFO are allowed before and during the serial
programming sequence. In this case, the programming of all offset bits
does not have to occur at once. A select number of bits can be written to
the SI input and then, by bringing LD and SEN HIGH, data can be written
to FIFO memory via Dn by toggling WEN. When WEN is brought HIGH with
LD and SEN restored to a LOW, the next offset bit in sequence is written
to the registers via SI. If an interruption of serial programming is desired,
it is sufficient either to set LD LOW and deactivate SEN or to set SEN LOW
and deactivate LD. Once LD and SEN are both restored to a LOW level,
serial offset programming continues.

From the time serial programming has begun, neither partial flag will be
valid until the full set of bits required to fill all the offset registers has been
written. Measuring from the rising WCLK edge that achieves the above
criteria; PAF will be valid after two more rising WCLK edges plus tPAF, PAE
will be valid after the next two rising RCLK edges plus tPAE plus tSKEW2.

It is not possible to read the flag offset values in a serial mode.

PARALLEL MODE

If Parallel Programming mode has been selected, as described above, then
programming of PAE and PAF values can be achieved by using a combination
of the LD, WCLK , WEN and Dn input pins.

Programming PAE and PAF proceeds as follows: when LD and WEN are
set LOW, data on the inputs Dn are written into the Empty Offset LSB Register
on the first LOW-to-HIGH transition of WCLK. Upon the second LOW-to-HIGH
transition of WCLK, data are written into the Empty Offset Mid-Byte Register.
Upon the third LOW-to-HIGH transition of WCLK, data are written into the Empty
Offset MSB Register. Upon the fourth LOW-to-HIGH transition of WCLK, data
are written into the Full Offset LSB Register. Upon the fifth LOW-to-HIGH
transition of WCLK, data are written into the Full Offset Mid-Byte Register. Upon
the sixth LOW-to-HIGH transition of WCLK, data are written into the Full Offset
MSB Register. The seventh transition of WCLK writes, once again, into the
Empty Offset LSB Register. See Figure 14, Parallel Loading of Programmable
Flag Registers, for the timing diagram for this mode.

The act of writing offsets in parallel employs a dedicated write offset register
pointer. The act of reading offsets employs a dedicated read offset register
pointer. The two pointers operate independently; however, a read and a write
should not be performed simultaneously to the offset registers. A Master Reset
initializes both pointers to the Empty Offset (LSB) register. A Partial Reset has
no effect on the position of these pointers.

Write operations to the FIFO are allowed before and during the parallel
programming sequence. In this case, the programming of all offset registers does
not have to occur at one time. One, two or more offset registers can be written
and then by bringing LD HIGH, write operations can be redirected to the FIFO
memory. When LD is set LOW again, and WEN is LOW, the next offset register
in sequence is written to. As an alternative to holding WEN LOW and toggling
LD, parallel programming can also be interrupted by setting LD LOW and
toggling WEN.

Note that the status of a partial flag (PAE or PAF) output is invalid during the
programming process. From the time parallel programming has begun, a partial
flag output will not be valid until the appropriate offset word has been written to
the register(s) pertaining to that flag. Measuring from the rising WCLK edge that
achieves the above criteria; PAF will be valid after two more rising WCLK edges
plus t

PAF, PAE will be valid after the next two rising RCLK edges plus tPAE plus

t

SKEW2.

The act of reading the offset registers employs a dedicated read offset
register pointer. The contents of the offset registers can be read on the Q0-
Qn pins when LD is set LOW and REN is set LOW.

For the IDT72V2101/72V2111, data is read via Qn from the Empty Offset
LSB Register on the first LOW-to-HIGH transition of RCLK. Upon the second
LOW-to-HIGH transition of RCLK, data are read from the Empty Offset Mid-Byte
Register. Upon the third LOW-to-HIGH transition of RCLK, data are read from
the Empty Offset MSB Register. Upon the fourth LOW-to-HIGH transition of
RCLK, data are read from the Full Offset LSB Register. Upon the fifth LOW­to-HIGH transition of RCLK, data are read from the Full Offset Mid-Byte Register.
Upon the sixth LOW-to-HIGH transition of RCLK, data are read from the Full
Offset MSB Register. The seventh transition of RCLK reads, once again, from
the Empty Offset LSB Register. See Figure 15, Parallel Read of Programmable
Flag Registers, for the timing diagram for this mode.

It is permissible to interrupt the offset register read sequence with reads or
writes to the FIFO. The interruption is accomplished by deasserting REN, LD,
or both together. When REN and LD are restored to a LOW level, reading of
the offset registers continues where it left off. It should be noted, and care should
be taken from the fact that when a parallel read of the flag offsets is performed,
the data word that was present on the output lines Qn will be overwritten.

Parallel reading of the offset registers is always permitted regardless of
which timing mode (IDT Standard or FWFT modes) has been selected.

RETRANSMIT OPERATION

The Retransmit operation allows data that has already been read to be
accessed again. There are two stages: first, a setup procedure that resets
the read pointer to the first location of memory, then the actual retransmit,
which consists of reading out the memory contents, starting at the beginning
of memory.

Retransmit setup is initiated by holding RT LOW during a rising RCLK
edge. REN and WEN must be HIGH before bringing RT LOW. At least two
words, but no more than D - 2 words should have been written into the FIFO
and read from the FIFO between Reset (Master or Partial) and the time of
Retransmit setup. D = 262,144 for the IDT72V2101 and D = 524,288 for the
IDT72V2111 in IDT Standard mode. In FWFT mode, D = 262,145 for the
IDT72V2101 and D = 524,289 for the IDT72V2111.

If IDT Standard mode is selected, the FIFO will mark the beginning of the
Retransmit setup by setting EF LOW. The change in level will only be noticeable
if EF was HIGH before setup. During this period, the internal read pointer is
initialized to the first location of the RAM array.

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When EF goes HIGH, Retransmit setup is complete and read operations
may begin starting with the first location in memory. Since IDT Standard
mode is selected, every word read including the first word following
Retransmit setup requires a LOW on REN to enable the rising edge of RCLK.
See Figure 11, Retransmit Timing (IDT Standard Mode), for the relevant timing
diagram.

If FWFT mode is selected, the FIFO will mark the beginning of the
Retransmit setup by setting OR HIGH. During this period, the internal read
pointer is set to the first location of the RAM array.

When OR goes LOW, Retransmit setup is complete; at the same time,
the contents of the first location appear on the outputs. Since FWFT mode
is selected, the first word appears on the outputs, no LOW on REN is necessary.

Reading all subsequent words requires a LOW on REN to enable the rising edge
of RCLK. See Figure 12, Retransmit Timing (FWFT Mode), for the relevant
timing diagram.

For either IDT Standard mode or FWFT mode, updating of the PAE, HF
and PAF flags begin with the rising edge of RCLK that RT is setup. PAE is
synchronized to RCLK, thus on the second rising edge of RCLK after RT is
setup, the PAE flag will be updated. HF is asynchronous, thus the rising
edge of RCLK that RT is setup will update HF. PAF is synchronized to
WCLK, thus the second rising edge of WCLK that occurs tSKEW after the
rising edge of RCLK that RT is setup will update PAF. RT is synchronized
to RCLK.

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SIGNAL DESCRIPTION

INPUTS:

DATA IN (D0 - D8)

Data inputs for 9-bit wide data.

CONTROLS:

MASTER RESET (MRS)

A Master Reset is accomplished whenever the MRS input is taken to a
LOW state. This operation sets the internal read and write pointers to the
first location of the RAM array. PAE will go LOW, PAF will go HIGH, and
HF will go HIGH.

If FWFT is LOW during Master Reset then the IDT Standard mode,
along with EF and FF are selected. EF will go LOW and FF will go HIGH.
If FWFT is HIGH, then the First Word Fall Through mode (FWFT), along with
IR and OR, are selected. OR will go HIGH and IR will go LOW.

If LD is LOW during Master Reset, then PAE is assigned a threshold 127
words from the empty boundary and PAF is assigned a threshold 127 words
from the full boundary; 127 words corresponds to an offset value of 07FH.
Following Master Reset, parallel loading of the offsets is permitted, but not
serial loading.

If LD is HIGH during Master Reset, then PAE is assigned a threshold
1,023 words from the empty boundary and PAF is assigned a threshold
1,023 words from the full boundary; 1,023 words corresponds to an offset
value of 3FFH. Following Master Reset, serial loading of the offsets is
permitted, but not parallel loading.

Parallel reading of the registers is always permitted. (See section
describing the LD pin for further details.)

During a Master Reset, the output register is initialized to all zeroes. A
Master Reset is required after power up, before a write operation can take
place. MRS is asynchronous.

See Figure 5, Master Reset Timing, for the relevant timing diagram.
PARTIAL RESET (PRS)

A Partial Reset is accomplished whenever the PRS input is taken to a LOW
state. As in the case of the Master Reset, the internal read and write pointers are
set to the first location of the RAM array, PAE goes LOW, PAF goes HIGH, and
HF goes HIGH.

Whichever mode is active at the time of Partial Reset, IDT Standard mode
or First Word Fall Through, that mode will remain selected. If the IDT Standard
mode is active, then FF will go HIGH and EF will go LOW. If the First Word Fall
Through mode is active, then OR will go HIGH, and IR will go LOW.

Following Partial Reset, all values held in the offset registers remain
unchanged. The programming method (parallel or serial) currently active
at the time of Partial Reset is also retained. The output register is initialized
to all zeroes. PRS is asynchronous.

A Partial Reset is useful for resetting the device during the course of
operation, when reprogramming partial flag offset settings may not be
convenient.

See Figure 6, Partial Reset Timing, for the relevant timing diagram.
RETRANSMIT (RT)

The Retransmit operation allows data that has already been read to be
accessed again. There are two stages: first, a setup procedure that resets the
read pointer to the first location of memory, then the actual retransmit, which
consists of reading out the memory contents, starting at the beginning of the
memory.

Retransmit setup is initiated by holding RT LOW during a rising RCLK edge.

REN and WEN must be HIGH before bringing RT LOW.

If IDT Standard mode is selected, the FIFO will mark the beginning of
the Retransmit setup by setting EF LOW. The change in level will only be
noticeable if EF was HIGH before setup. During this period, the internal
read pointer is initialized to the first location of the RAM array.

When EF goes HIGH, Retransmit setup is complete and read operations
may begin starting with the first location in memory. Since IDT Standard
mode is selected, every word read including the first word following
Retransmit setup requires a LOW on REN to enable the rising edge of
RCLK. See Figure 11, Retransmit Timing (IDT Standard Mode), for the
relevant timing diagram.

If FWFT mode is selected, the FIFO will mark the beginning of the Retransmit
setup by setting OR HIGH. During this period, the internal read pointer is set to
the first location of the RAM array.

When OR goes LOW, Retransmit setup is complete; at the same time,
the contents of the first location appear on the outputs. Since FWFT mode
is selected, the first word appears on the outputs, no LOW on REN is
necessary. Reading all subsequent words requires a LOW on REN to
enable the rising edge of RCLK. See Figure 12, Retransmit Timing (FWFT
Mode), for the relevant timing diagram.

FIRST WORD FALL THROUGH/SERIAL IN (FWFT/SI)

This is a dual purpose pin. During Master Reset, the state of the FWFT/SI
input determines whether the device will operate in IDT Standard mode or First
Word Fall Through (FWFT) mode.

If, at the time of Master Reset, FWFT/SI is LOW, then IDT Standard
mode will be selected. This mode uses the Empty Flag (EF) to indicate
whether or not there are any words present in the FIFO memory. It also uses
the Full Flag function (FF) to indicate whether or not the FIFO memory has
any free space for writing. In IDT Standard mode, every word read from the
FIFO, including the first, must be requested using the Read Enable (REN)
and RCLK.

If, at the time of Master Reset, FWFT/SI is HIGH, then FWFT mode will
be selected. This mode uses Output Ready (OR) to indicate whether or not
there is valid data at the data outputs (Q

n). It also uses Input Ready (IR) to

indicate whether or not the FIFO memory has any free space for writing. In
the FWFT mode, the first word written to an empty FIFO goes directly to Q

n

after three RCLK rising edges, REN = LOW is not necessary. Subsequent
words must be accessed using the Read Enable (REN) and RCLK.

After Master Reset, FWFT/SI acts as a serial input for loading PAE and
PAF offsets into the programmable registers. The serial input function can
only be used when the serial loading method has been selected during
Master Reset. Serial programming using the FWFT/SI pin functions the
same way in both IDT Standard and FWFT modes.

WRITE CLOCK (WCLK)

A write cycle is initiated on the rising edge of the WCLK input. Data setup
and hold times must be met with respect to the LOW-to-HIGH transition of
the WCLK. It is permissible to stop the WCLK. Note that while WCLK is idle,
the FF/IR, PAF and HF flags will not be updated. (Note that WCLK is only
capable of updating HF flag to LOW.) The Write and Read Clocks can either
be independent or coincident.

WRITE ENABLE (WEN)

When the WEN input is LOW, data may be loaded into the FIFO RAM array
on the rising edge of every WCLK cycle if the device is not full. Data is stored
in the RAM array sequentially and independently of any ongoing read
operation.

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TEMPERATURE RANGES

When WEN is HIGH, no new data is written in the RAM array on each WCLK

cycle.

To prevent data overflow in the IDT Standard mode, FF will go LOW,
inhibiting further write operations. Upon the completion of a valid read cycle,
FF will go HIGH allowing a write to occur. The FF is updated by two WCLK
cycles + t

SKEW after the RCLK cycle.

To prevent data overflow in the FWFT mode, IR will go HIGH, inhibiting
further write operations. Upon the completion of a valid read cycle, IR will
go LOW allowing a write to occur. The IR flag is updated by two WCLK
cycles + t

SKEW after the valid RCLK cycle.

WEN is ignored when the FIFO is full in either FWFT or IDT Standard mode.

READ CLOCK (RCLK)

A read cycle is initiated on the rising edge of the RCLK input. Data can
be read on the outputs, on the rising edge of the RCLK input. It is permissible
to stop the RCLK. Note that while RCLK is idle, the EF/OR, PAE and HF
flags will not be updated. (Note that RCLK is only capable of updating the
HF flag to HIGH.) The Write and Read Clocks can be independent or
coincident.

READ ENABLE (REN)

When Read Enable is LOW, data is loaded from the RAM array into the
output register on the rising edge of every RCLK cycle if the device is not
empty.

When the REN input is HIGH, the output register holds the previous data
and no new data is loaded into the output register. The data outputs Q0-Q
maintain the previous data value.

In the IDT Standard mode, every word accessed at Qn, including the first
word written to an empty FIFO, must be requested using REN. When the
last word has been read from the FIFO, the Empty Flag (EF) will go LOW,
inhibiting further read operations. REN is ignored when the FIFO is empty.
Once a write is performed, EF will go HIGH allowing a read to occur. The
EF flag is updated by two RCLK cycles + tSKEW after the valid WCLK cycle.

In the FWFT mode, the first word written to an empty FIFO automatically
goes to the outputs Qn, on the third valid LOW to HIGH transition of RCLK
+ tSKEW after the first write. REN does not need to be asserted LOW. In
order to access all other words, a read must be executed using REN. The
RCLK LOW to HIGH transition after the last word has been read from the
FIFO, Output Ready (OR) will go HIGH with a true read (RCLK with REN =
LOW), inhibiting further read operations. REN is ignored when the FIFO is
empty.

LOAD (LD)

This is a dual purpose pin. During Master Reset, the state of the LD input
determines one of two default offset values (127 or 1,023) for the PAE and PAF
flags, along with the method by which these offset registers can be pro­grammed, parallel or serial. After Master Reset, LD enables write operations
to and read operations from the offset registers. Only the offset loading method
currently selected can be used to write to the registers. Offset registers can be
read only in parallel. A LOW on LD during Master Reset selects a default PAE
offset value of 07FH (a threshold 127 words from the empty boundary), a default
PAF offset value of 07FH (a threshold 127 words from the full boundary), and
parallel loading of other offset values. A HIGH on LD during Master Reset
selects a default PAE offset value of 3FFH (a threshold 1,023 words from the
empty boundary), a default PAF offset value of 3FFH (a threshold 1,023 words
from the full boundary), and serial loading of other offset values.

After Master Reset, the LD pin is used to activate the programming
process of the flag offset values PAE and PAF. Pulling LD LOW will begin
a serial loading or parallel load or read of these offset values. See Figure 4,
Programmable Flag Offset Programming Sequence.

OUTPUTS:

FULL FLAG (FF/IR)

This is a dual purpose pin. In IDT Standard mode, the Full Flag (FF)
function is selected. When the FIFO is full, FF will go LOW, inhibiting further
write operations. When FF is HIGH, the FIFO is not full. If no reads are
performed after a reset (either MRS or PRS), FF will go LOW after D writes to

n

the FIFO (D = 262,144 for the IDT72V2101 and 524,288 for the IDT72V2111
See Figure 7, Write Cycle and Full Flag Timing (IDT Standard Mode), for the
relevant timing information.

In FWFT mode, the Input Ready (IR) function is selected. IR goes LOW
when memory space is available for writing in data. When there is no longer
any free space left, IR goes HIGH, inhibiting further write operations. If no
reads are performed after a reset (either MRS or PRS), IR will go HIGH after
D writes to the FIFO (D = 262,145 for the IDT72V2101 and 524,289 for the
IDT72V2111) See Figure 9, Write Timing (FWFT Mode), for the relevant
timing information.

The IR status not only measures the contents of the FIFO memory, but
also counts the presence of a word in the output register. Thus, in FWFT
mode, the total number of writes necessary to deassert IR is one greater
than needed to assert FF in IDT Standard mode.

FF/IR is synchronous and updated on the rising edge of WCLK.
double register-buffered outputs.

FF/IR are

).

SERIAL ENABLE (SEN)

The SEN input is an enable used only for serial programming of the
offset registers. The serial programming method must be selected during
Master Reset. SEN is always used in conjunction with LD. When these lines
are both LOW, data at the SI input can be loaded into the program register
one bit for each LOW-to-HIGH transition of WCLK. (See Figure 4.)

When SEN is HIGH, the programmable registers retains the previous
settings and no offsets are loaded. SEN functions the same way in both IDT
Standard and FWFT modes.

OUTPUT ENABLE (OE)

When Output Enable is enabled (LOW), the parallel output buffers receive
data from the output register. When OE is HIGH, the output data bus (Qn) goes
into a high impedance state.

EMPTY FLAG (EF/OR)

This is a dual purpose pin. In the IDT Standard mode, the Empty Flag
(EF) function is selected. When the FIFO is empty, EF will go LOW,
inhibiting further read operations. When EF is HIGH, the FIFO is not empty. See
Figure 8, Read Cycle, Empty Flag and First Word Latency Timing (IDT
Standard Mode), for the relevant timing information.

In FWFT mode, the Output Ready (OR) function is selected. OR goes
LOW at the same time that the first word written to an empty FIFO appears valid
on the outputs. OR stays LOW after the RCLK LOW to HIGH transition that shifts
the last word from the FIFO memory to the outputs. OR goes HIGH only with
a true read (RCLK with REN = LOW). The previous data stays at the outputs,
indicating the last word was read. Further data reads are inhibited until OR goes
LOW again.

See Figure 10, Read Timing (FWFT Mode), for the relevant timing

information.

14

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

EF/OR is synchronous and updated on the rising edge of RCLK.

In IDT Standard mode, EF is a double register-buffered output. In FWFT

mode, OR is a triple register-buffered output.

PROGRAMMABLE ALMOST-FULL FLAG (PAF)

The Programmable Almost-Full flag (PAF) will go LOW when th

e FIFO
reaches the almost-full condition. In IDT Standard mode, if no reads are
performed after reset (MRS), PAF will go LOW after (D - m) words are written
to the FIFO. The PAF will go LOW after (262,144-m) writes for the IDT72V2101
and (524,288-m) writes for the IDT72V2111. The offset “m” is the full offset
value. The default setting for this value is stated in the footnote of Table 1.

In FWFT mode, the PAF will go LOW after (262,145-m) writes for the
IDT72V2101 and (524,289-m) writes for the IDT72V2111, where m is the
full offset value. The default setting for this value is stated in the footnote
of Table 2.

See Figure 16, Programmable Almost-Full Flag Timing (IDT Standard and
FWFT Mode), for the relevant timing information.

PAF is synchronous and updated on the rising edge of WCLK.

PROGRAMMABLE ALMOST-EMPTY FLAG (PAE)

The Programmable Almost-Empty flag (PAE) will go LOW when the FIFO
reaches the almost-empty condition. In IDT Standard mode, PAE will go LOW
when there are n words or less in the FIFO.

The offset “n” is the empty offset

value. The default setting for this value is stated in the footnote of Table 1.

In FWFT mode, the PAE will go LOW when there are n+1 words or less

in the FIFO.

The default setting for this value is stated in the footnote of Table 2.

See Figure 17, Programmable Almost-Empty Flag Timing (IDT Standard

and FWFT Mode), for the relevant timing information.

PAE is synchronous and updated on the rising edge of RCLK.

HALF-FULL FLAG (HF)

This output indicates a half-full FIFO. The rising WCLK edge that fills the FIFO
beyond half-full sets HF LOW. The flag remains LOW until the difference between
the write and read pointers becomes less than or equal to half of the total depth
of the device; the rising RCLK edge that accomplishes this condition sets HF
HIGH.

In IDT Standard mode, if no reads are performed after reset (MRS or
PRS), HF will go LOW after (D/2 + 1) writes to the FIFO, where D = 262,144
for the

IDT72V2101 and

524,288 for the

IDT72V2111.

In FWFT mode, if no reads are performed after reset (MRS or PRS), HF
will go LOW after (D-1/2 + 2) writes to the FIFO, where D = 262,145 for the
IDT72V2101 and

524,289 for the

IDT72V2111.

See Figure 18, Half-Full Flag Timing (IDT Standard and FWFT Modes),
for the relevant timing information. Because HF is updated by both RCLK
and WCLK, it is considered asynchronous.

DATA OUTPUTS (Q0-Q8)

(Q0 - Q8) are data outputs for 9-bit wide data.

15

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

MRS

REN

WEN

t

FWFT

FWFT/SI

LD

RT

SEN

t

RSF

COMMERCIAL AND INDUSTRIAL

t

RS

t

t

t

t

t

RSS

t

RSS

RSS

RSS

RSS

RSR

t

RSR

t

RSR

t

RSR

TEMPERATURE RANGES

If FWFT = HIGH, OR = HIGH

EF/OR

FF/IR

PAE

PAF, HF

Q0 - Q

If FWFT = LOW, EF = LOW

t

RSF

If FWFT = LOW, FF = HIGH
If FWFT = HIGH, IR = LOW

t

RSF

t

RSF

t

RSF

n

OE = HIGH

OE = LOW

4669 drw 08

Figure 5. Master Reset Timing

16

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

PRS

REN

WEN

RT

SEN

t

RS

t

RSS

t

t

RSS

t

RSS

RSS

t

RSR

t

RSR

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

EF/OR

FF/IR

PAE

PAF, HF

0

- Q

Q

t

RSF

t

RSF

t

RSF

t

RSF

t

RSF

n

If FWFT = HIGH, OR = HIGH

If FWFT = LOW, EF = LOW

If FWFT = LOW, FF = HIGH

If FWFT = HIGH, IR = LOW

OE = HIGH

OE = LOW

4669 drw 09

Figure 6. Partial Reset Timing

17

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

WCLK

D0 - D

n

TM

262,144 x 9, 524,288 x 9

NO WRITE

t

SKEW1

(1)

1

t

t

CLKH

2

t

DS

t

WFF

CLK

t

CLKL

(1)

t

t

DH

D

X

t

WFF

SKEW1

NO WRITE

1

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

2

t

DS

t

WFF

DX+1

t

DH

t

WFF

WEN

RCLK

t

t

t

t

ENS

ENH

ENS

ENH

REN

t

A

4669 drw 10

Q0 - Q

t

A

n

DATA READ NEXT DATA READDATA IN OUTPUT REGISTER

NOTES:

1. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF will go high (after one WCLK cycle pus tWFF). If the time between the rising
edge of the RCLK and the rising edge of the WCLK is less than t

SKEW1, then the FF deassertion may be delayed one extra WCLK cycle.

2. LD = HIGH, OE = LOW, EF = HIGH

RCLK

REN

Q0 - Q

WCLK

WEN

D0 - D

EF

OE

Figure 7. Write Cycle and Full Flag Timing (IDT Standard Mode)

t

CLKH

t

REF

CLK

t

CLKL

t

t

t

t

ENS

ENH

t

A

LAST WORD

t

OLZ

ENS

D

ENH

t

REF

t

A

0

4669 drw 11

D

1

1

t

ENS

n

n

t

t

OLZ

ENH

NO OPERATION

t

REF

t

A

LAST WORD

t

t

OE

(1)

t

SKEW1

t

t

ENS

ENH

t

DHS

t

DS

D

0

OHZ

t

t

DS

ENS

D

1

2

NO OPERATION

t

ENH

t

DH

t

NOTES:

SKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH (after one RCLK cycle plus tREF). If the time between the rising edge

1. t
of WCLK and the rising edge of RCLK is less than t

SKEW1, then EF deassertion may be delayed one extra RCLK cycle.

2. LD = HIGH.

3. First word latency: t

SKEW1 + 1*TRCLK + tREF.

Figure 8. Read Cycle, Empty Flag and First Data Word Latency Timing (IDT Standard Mode)

18

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

1

TM

262,144 x 9, 524,288 x 9

ENH

t

D

W

[D-1]

W

[D-m+2]

W

[D-m+1]

W

[D-m]

W

[D-m-1]

W

DS

t

[D-m-2]

W

][

PAF

t

WFF

t

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

4669 drw 12

ENS

t

W

][

W

DS

t

][

HF

t

W

[n+4]

2

W

(2)

PAE

[n+3]

SKEW2

1

W

t

1

[n +2]

W

DS

t

4

W

3

3

W

2

(1)

2

W

1

SKEW1

t

DH

t

1

W

DS

t

W

A

REF

t

t

DATA IN OUTPUT REGISTER

t

Figure 9. Write Timing (First Word Fall Through Mode)

SKEW1 + 2*TRCLK + tREF.

WCLK

WEN

8

- D

0

D

RCLK

REN

8

- Q

0

Q

OR

PAE

HF

19

PAF

IR

SKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that OR will go LOW after two RCLK cycles plus tREF. If the time between the rising edge of WCLK and the rising edge of RCLK is less than

SKEW1, then OR assertion may be delayed one extra RCLK cycle.

SKEW2 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that PAE will go HIGH after one RCLK cycle plus tPAE. If the time between the rising edge of WCLK and the rising edge of RCLK is less than

SKEW2, then the PAE deassertion may be delayed one extra RCLK cycle.

t

t

4. n = PAE offset, m = PAF offset and D = maximum FIFO depth.

3. LD = HIGH, OE = LOW

5. D = 262,145 for the IDT72V2101 and 524,289 for the IDT72V2111.

NOTES:

1. t

2. t

6. First word latency: t

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

A

ENS

t

t

D

W

[D-1]

W

[D-n+2]

W

[D-n+1]

W

REF

t

1

[D-n]

W

A

t

PAE

t

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

4669 drw 13

(2)

SKEW2

t

(1)

SKEW1

t

12

ENH

DH

t

t

D

W

ENS

t

A

t

A

t

OE

t

OHZ

t

[D-n-1]

W

][

W

][

W

[m+4]

W

[m+3]

W

A

t

HF

t

PAF

t

Figure 10. Read Timing (First Word Fall Through Mode)

m+2

W

WFF

3

W

A

t

2

W

1

W

1

W

t

WFF

t

ENS

t

WCLK

WEN

DS

t

8

- D

0

D

RCLK

REN

OE

8

- Q

0

Q

OR

PAE

HF

PAF

IR

SKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that IR will go LOW after one WCLK cycle plus tWFF. If the time between the rising edge of RCLK and the rising edge of WCLK is less than

SKEW1, then the IR assertion may be delayed one extra WCLK cycle.

SKEW2 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that PAF will go HIGH after one WCLK cycle plus tPAF. If the time between the rising edge of RCLK and the rising edge of WCLK is less than

SKEW2, then the PAF deassertion may be delayed one extra WCLK cycle.

t

t

2. t

3. LD = HIGH

4. n = PAE Offset, m = PAF offset and D = maximum FIFO depth.

NOTES:

1. t

5. D = 262,145 for the IDT72V2101 and 524,289 for the IDT72V2111.

20

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

RCLK

REN

Q

0

- Q

WCLK

WEN

PAE

RT

EF

1

t

ENS

n

W

x

t

t

ENH

A

t

RTS

t

SKEW2

t

ENS

W

x+1

2

t

ENH

t

A

(3)

W

1

t

A

(3)

W

2

12

t

RTS

t

t

ENS

ENH

t

t

REF

HF

t

REF

t

PAE

HF

t

PAF

PAF

4669 drw 14

NOTES:

1. Retransmit setup is complete after EF returns HIGH, only then can a read operation begin.

2. OE = LOW.

1 = first word written to the FIFO after Master Reset, W2 = second word written to the FIFO after Master Reset.

3. W

4. No more than D - 2 may be written to the FIFO between Reset (Master or Partial) and Retransmit setup. Therefore, FF will be HIGH throughout the Retransmit setup procedure. D = 262,144

for the IDT72V2101 and 524,288 for the IDT72V2111.

5. There must be at least two words written to the FIFO before a Retransmit operation can be invoked.

Figure 11. Retransmit Timing (IDT Standard Mode)

21

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

RCLK

t

t

ENS

ENH

t

RTS

1

t

ENS

2

3

4

t

ENH

REN

t

0

- Q

Q

WCLK

A

n

W

x

t

RTS

W

x+1

t

SKEW2

12

W

t

A

(4)

1

W

t

A

(4)

2

(4)

W

3

t

A

W

4

WEN

t

t

ENH

REF

t

REF

RT

t

ENS

OR

t

PAE

PAE

t

HF

HF

t

PAF

PAF

4669 drw 15

NOTES:

1. Retransmit setup is complete after OR returns LOW.

2. No more than D - 2 words may be written to the FIFO between Reset (Master or Partial) and Retransmit setup. Therefore, IR will be LOW throughout the Retransmit setup

procedure. D = 262,145 for the IDT72V2101 and 524,289 for the IDT72V2111.

3. OE = LOW

4. W

1, W2, W3 = first, second and third words written to the FIFO after Master Reset.

5. There must be at least two words written to the FIFO before a Retransmit operation can be invoked.

WCLK

t

t

ENS

ENH

SEN

t

t

LDS

LDH

LD

t

DS

SI

NOTE:

1. X = 17 for the IDT72V2101 and X = 18 for the IDT72V2111.

BIT 0

EMPTY OFFSET

Figure 12. Retransmit Timing (FWFT Mode)

(1)

BIT X

BIT 0

FULL OFFSET

t

ENH

t

LDH

t

BIT X

DH

(1)

4669 drw 16

Figure 13. Serial Loading of Programmable Flag Registers (IDT Standard and FWFT Modes)

22

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

WCLK

TM

262,144 x 9, 524,288 x 9

t

CLK

t

CLKH

t

CLKL

t

LDS

t

LDH

LD

t

ENS

t

ENH

WEN

t

DS

0

- D

7

D

PAE OFFSET

(LSB)

t

DH

PAE OFFSET

(MID-BYTE)

Figure 14. Parallel Loading of Programmable Flag Registers (IDT Standard and FWFT Modes)

t

CLK

t

CLKH

t

CLKL

RCLK

t

t

LDS

LDH

LD

t

ENS

t

ENH

REN

t

A

Q

0

- Q

DATA IN OUTPUT REGISTER

7

PAE OFFSET

NOTE:

1. OE = LOW

Figure 15. Parallel Read of Programmable Flag Registers (IDT Standard and FWFT Modes)

(LSB)

PAE OFFSET

(MSB)

PAE OFFSET

(MID-BYTE)

PAF OFFSET

(LSB)

PAE OFFSET

(MSB)

PAF OFFSET

(MID-BYTE)

PAF OFFSET

(LSB)

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

t

LDH

t

ENH

t

DH

PAF OFFSET

(MSB)

t

PAF OFFSET

(MID-BYTE)

A

t

LDH

t

ENH

4669 drw 17

PAF OFFSET

(MSB)

4669 drw 18

t

WCLK

CLKH

t

ENS

t

CLKL

1

t

ENH

2

WEN

t

PAF

PAF

D - (m+1) words in FIFO

(2)

(3)

t

SKEW2

D - m words in FIFO

RCLK

t

t

ENS

ENH

REN

NOTES:

1. m = PAF offset .

2. D = maximum FIFO depth.
In IDT Standard mode: D = 262,144 for the IDT72V2101 and 524,288 for the IDT72V2111.
In FWFT mode: D = 262,145 for the IDT72V2101 and 524,289 for the IDT72V2111.
t

SKEW2

is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that PAF will go HIGH (after one WCLK cycle plus t

3.
RCLK and the rising edge of WCLK is less than t

SKEW2

, then the PAF deassertion time may be delayed one extra WCLK cycle.

4. PAF is asserted and updated on the rising edge of WCLK only.

Figure 16. Programmable Almost-Full Flag Timing (IDT Standard and FWFT Modes)

23

12

t

PAF

(2)

D-(m+1) words
in FIFO

4669 drw 19

PAF

). If the time between the rising edge of

(2)

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

t

CLKH

TM

262,144 x 9, 524,288 x 9

t

CLKL

WCLK

t

t

ENS

ENH

WEN

(2)

PAE

RCLK

n words in FIFO
n+1 words in FIFO

,

(3)

(4)

t

SKEW2

12 12

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

(2)

(2)

n+1 words in FIFO

t

ENS

n+2 words in FIFO

t

PAE

,

(3)

t

ENH

t

PAE

n words in FIFO
n+1 words in FIFO

,

(3)

REN

4669 drw 20

NOTES:

1. n = PAE offset.

2. For IDT Standard mode

3. For FWFT mode.
tSKEW2 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that PAE will go HIGH (after one RCLK cycle plus tPAE). If the time between the rising edge of

4.
WCLK and the rising edge of RCLK is less than t

SKEW2, then the PAE deassertion may be delayed one extra RCLK cycle.

5. PAE is asserted and updated on the rising edge of WCLK only.

Figure 17. Programmable Almost-Empty Flag Timing (IDT Standard and FWFT Modes)

t

t

ENS

CLKL

t

ENH

WCLK

t

CLKH

WEN

t

HF

D/2 words in FIFO

D-1

[

+ 1] words in FIFO

2

(1)

HF

,

(2)

D/2 + 1 words in FIFO

D-1

2

[

+ 2] words in FIFO

RCLK

t

ENS

REN

NOTES:

1. For IDT Standard mode: D = maximum FIFO depth. D = 262,144 for the IDT72V2101 and 524,288 for the IDT72V2111.

2. For FWFT mode: D = maximum FIFO depth. D = 262,145 for the IDT72V2101 and 524,289 for the IDT72V2111.

Figure 18. Half-Full Flag Timing (IDT Standard and FWFT Modes)

24

(1)

,

(2)

t

HF

D/2 words in FIFO

D-1

2

[

+ 1] words in FIFO

(1)

,

(2)

4669 drw 21

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

TM

262,144 x 9, 524,288 x 9

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

OPTIONAL CONFIGURATIONS

WIDTH EXPANSION CONFIGURATION

Word width may be increased simply by connecting together the control
signals of multiple devices. Status flags can be detected from any one
device. The exceptions are the EF and FF functions in IDT Standard mode
and the IR and OR functions in FWFT mode. Because of variations in skew
between RCLK and WCLK, it is possible for EF/FF deassertion and IR/OR
assertion to vary by one cycle between FIFOs. In IDT Standard mode, such

PARTIAL RESET (PRS)
MASTER RESET (MRS)

FIRST WORD FALL THROUGH/

SERIAL INPUT (FWFT/SI)

GATE

DATA IN

(1)

RETRANSMIT (RT)

m + n m n

FULL FLAG/INPUT READY (FF/IR)

FULL FLAG/INPUT READY (FF/IR) #2

D0 - Dm

WRITE CLOCK (WCLK)

WRITE ENABLE (WEN)

LOAD (LD)

PROGRAMMABLE (PAF)

HALF-FULL FLAG (HF)

72V2101
72V2111

#1

IDT

FIFO

#1

Dm

+1

m

problems can be avoided by creating composite flags, that is, ANDing EF of
every FIFO, and separately ANDing FF of every FIFO. In FWFT mode,
composite flags can be created by ORing OR of every FIFO, and separately
ORing IR of every FIFO.

Figure 19 demonstrates a width expansion using two IDT72V2101/

72V2111 devices. D

0 - D8 from each device form an 18-bit wide input bus and

Q0-Q8 from each device form an 18-bit wide output bus. Any word width can
be attained by adding additional IDT72V2101/72V2111 devices.

- Dn

READ CLOCK (RCLK)

READ ENABLE (REN)
OUTPUT ENABLE (OE)

IDT
72V2101
72V2111

FIFO

#2

PROGRAMMABLE (PAE)

EMPTY FLAG/OUTPUT READY (EF/OR) #1
EMPTY FLAG/OUTPUT READY (EF/OR) #2

n

Qm

+1

- Qn

m + n

DATA OUT

GATE

(1)

NOTES:

1. Use an AND gate in IDT Standard mode, an OR gate in FWFT mode.

2. Do not connect any output control signals directly together.

3. FIFO #1 and FIFO #2 must be the same depth, but may be different word widths.

Figure 19. Block Diagram of 262,144 x 18 and 524,288 x 18 Width Expansion

Q

0

- Qm

4669 drw 22

25

IDT72V2101/72V2111 3.3V HIGH DENSITY CMOS
SUPERSYNC FIFO

FWFT/SI

TM

262,144 x 9, 524,288 x 9

TRANSFER CLOCK

COMMERCIAL AND INDUSTRIAL

TEMPERATURE RANGES

WRITE CLOCK

WRITE ENABLE

INPUT READY

DATA IN

n n

WCLK

WEN

IR

Dn

FWFT/SI FWFT/SI

IDT
72V2101
72V2111

RCLK

OR

REN

OE

Qn

Figure 20. Block Diagram of 524,288 x 9 and 1,048,576 x 9 Depth Expansion

DEPTH EXPANSION CONFIGURATION (FWFT MODE ONLY)

The IDT72V2101 can easily be adapted to applications requiring depths
greater than 262,144 and 524,288 for the IDT72V2111 with a 9-bit bus width.
In FWFT mode, the FIFOs can be connected in series (the data outputs of one
FIFO connected to the data inputs of the next) with no external logic necessary.
The resulting configuration provides a total depth equivalent to the sum of the
depths associated with each single FIFO. Figure 20 shows a depth expansion
using two IDT72V2101/72V2111 devices.

Care should be taken to select FWFT mode during Master Reset for all FIFOs
in the depth expansion configuration. The first word written to an empty
configuration will pass from one FIFO to the next ("ripple down") until it finally
appears at the outputs of the last FIFO in the chain–no read operation is
necessary but the RCLK of each FIFO must be free-running. Each time the
data word appears at the outputs of one FIFO, that device's OR line goes LOW,
enabling a write to the next FIFO in line.

For an empty expansion configuration, the amount of time it takes for OR of
the last FIFO in the chain to go LOW (i.e. valid data to appear on the last FIFO's
outputs) after a word has been written to the first FIFO is the sum of the delays
for each individual FIFO:

(N – 1)*(4*transfer clock) + 3*T

RCLK

where N is the number of FIFOs in the expansion and TRCLK is the RCLK
period. Note that extra cycles should be added for the possibility that the tSKEW1

READ CLOCK

READ ENABLE

OUTPUT READY

OUTPUT ENABLE

DATA OUT

GND

n

WCLK

WEN

IR

Dn

IDT
72V2101
72V2111

RCLK

REN

OR

OE

Qn

specification is not met between WCLK and transfer clock, or RCLK and transfer
clock, for the OR flag.

The "ripple down" delay is only noticeable for the first word written to an empty
depth expansion configuration. There will be no delay evident for subsequent
words written to the configuration.

The first free location created by reading from a full depth expansion
configuration will "bubble up" from the last FIFO to the previous one until it finally
moves into the first FIFO of the chain. Each time a free location is created in one
FIFO of the chain, that FIFO's IR line goes LOW, enabling the preceding FIFO
to write a word to fill it.

For a full expansion configuration, the amount of time it takes for IR of the first
FIFO in the chain to go LOW after a word has been read from the last FIFO is
the sum of the delays for each individual FIFO:

(N – 1)*(3*transfer clock) + 2 TWCLK

where N is the number of FIFOs in the expansion and TWCLK is the WCLK
period. Note that extra cycles should be added for the possibility that the tSKEW1
specification is not met between RCLK and transfer clock, or WCLK and transfer
clock, for the IR flag.

The Transfer Clock line should be tied to either WCLK or RCLK, whichever
is faster. Both these actions result in data moving, as quickly as possible, to the
end of the chain and free locations to the beginning of the chain.

4669 drw 23

26

ORDERING INFORMATION

IDT XXXXX

Device TypeXPower

NOTE:

1. Industrial temperature range product for the 15ns is available as a standard device.

XX

Speed

X

Package

Process /

Temperature

Range

X

BLANK

(1)

I
PF

10

15

20

L

72V2101
72V2111 524,288 x 9 3.3V SuperSyncFIFO

Commercial (0°C to +70°C)
Industrial (-40°C to +85°C)

Thin Plastic Quad Flatpack (TQFP, PN64-1)
Commercial Only

Com’l & Ind’l
Commercial Only

Low Power
262,144 x 9 3.3V SuperSyncFIFO

Clock Cycle Time (t
Speed in Nanoseconds

CLK

4669 drw24

)

DATASHEET DOCUMENT HISTORY

9/14/2000 pgs. 5.
12/18/2000 pgs. 5, 6 and 27.
03/27/2001 pgs. 6 and 27.

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The SuperSync FIFO is a trademark and the IDT logo is a registered trademark of Integrated Device Technology, Inc.

www.idt.com* PF Pkg: www.idt.com/docs/PSC4036.pdf

27