Cypress CY7C4291V 16 k / 32 k / 64 k / 128 k x 9 low-voltage deep sync fifo Datasheet


CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
16 K / 32 K / 64 K / 128 K × 9
Low-Voltage Deep Sync™ FIFOs
Features
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■
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■
■
■
■
■
■
■
■
■
■
■
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3.3 V operation for low-power consumption and easy
integration into low-voltage systems
High-speed, low-power, first-in first-out (FIFO) memories
16 K × 9 (CY7C4261V)
32 K × 9 (CY7C4271V)
64 K × 9 (CY7C4281V)
128 K × 9 (CY7C4291V)
0.35-micron CMOS for optimum speed or power
High-speed 100-MHz operation (10-ns read/write cycle
times)
Low power
❐ ICC = 25 mA
❐ ISB = 4 mA
Fully asynchronous and simultaneous read and write
operation
Empty, Full, and programmable Almost Empty and Almost
Full status flags
Output-enable (OE) pin
Independent read- and write-enable pins
Supports free-running 50% duty cycle clock inputs
Width-expansion capability
Pin-compatible 3.3 V solutions for CY7C4261/71/81/91
Pin-compatible density upgrade to CY7C42X1V family
Pb-free packages available
Functional Description
The CY7C4261/71/81/91V are high-speed, low-power FIFO
memories with clocked read and write interfaces. All are nine
bits wide. The CY7C4261/71/81/91V are pin-compatible to the
CY7C42x1V Synchronous FIFO family. Programmable
features include Almost Full/Almost Empty flags. These FIFOs
provide solutions for a wide variety of data buffering needs,
including high-speed data acquisition, multiprocessor
interfaces, and communications buffering.
These FIFOs have 9-bit input and output ports that are
controlled by separate clock and enable signals. The input port
is controlled by a free-running clock (WCLK) and two
write-enable pins (WEN1, WEN2/LD).
When WEN1 is LOW and WEN2/LD is HIGH, data is written
into the FIFO on the rising edge of the WCLK signal. While
WEN1 and WEN2/LD are held active, data is continually
written into the FIFO on each WCLK cycle. The output port is
controlled in a similar manner by a free-running read clock
(RCLK) and two read-enable pins (REN1, REN2). In addition,
the CY7C4261/71/81/91V has an output-enable pin (OE). The
read (RCLK) and write (WCLK) clocks may be tied together for
single-clock operation or the two clocks may be run
independently for asynchronous read/write applications. Clock
frequencies up to 100 MHz are achievable. Depth expansion
is possible using one enable input for system control, while the
other enable is controlled by expansion logic to direct the flow
of data.
The CY7C4261/71/81/91V provides four status pins: Empty,
Full, Programmable Almost Empty, and Programmable Almost
Full. The Almost Empty/Almost Full flags are programmable to
single word granularity. The programmable flags default to
Empty +7 and Full –7.
The flags are synchronous, that is, they change state relative
to either the read clock (RCLK) or the write clock (WCLK).
When entering or exiting the Empty and Almost Empty states,
the flags are updated exclusively by the RCLK. The flags
denoting Almost Full, and Full states are updated exclusively
by WCLK. The synchronous flag architecture guarantees that
the flags maintain their status for at least one cycle.
All configurations are fabricated using an advanced 0.35 
CMOS technology. Input ESD protection is greater than 2001
V, and latch-up is prevented by the use of guard rings.
Selection Guide
7C4261/71/81/91V-10
7C4261/71/81/91V-15
7C4261/71/81/91V-25
Unit
100
66.7
40
MHz
8
10
15
ns
Minimum cycle time
10
15
25
ns
Minimum data or enable setup
3.5
4
6
ns
Minimum data or enable hold
0
0
1
ns
Maximum flag delay
8
10
15
ns
Commercial
25
25
25
mA
Industrial
–
30
–
Maximum frequency
Maximum access time
Active power supply
current (ICC1)
CY7C4261V
CY7C4271V
CY7C4281V
CY7C4291V
Density
16 K x 9
32 K x 9
64 K x 9
128 K x 9
Package
32-pin PLCC
32-pin PLCC
32-pin PLCC
32-pin PLCC
Cypress Semiconductor Corporation
Document #: 38-06013 Rev. *F
•
198 Champion Court
•
San Jose, CA 95134-1709
•
408-943-2600
Revised March 30, 2011
[+] Feedback
CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Logic Block Diagram
D0–8
Input
Register
WCLK WEN1 WEN2/LD
Flag
Program
Register
Write
Control
Write
Pointer
RS
Flag
Logic
Dual Port
RAM Array
16 K/32 K
64 K/128 K
x9
EF
PAE
PAF
FF
Read
Pointer
Reset
Logic
Tristate
Output Register
Read
Control
OE
Q0–8
Document #: 38-06013 Rev. *F
RCLK REN1 REN2
Page 2 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Contents
Pin Configuration ............................................................. 4
Pin Definitions .................................................................. 4
Architecture ...................................................................... 5
Resetting the FIFO ............................................................ 5
FIFO Operation ................................................................. 5
Programming .................................................................... 5
Width-Expansion Configuration ...................................... 7
Flag Operation .................................................................. 7
Maximum Ratings ............................................................. 8
Switching Characteristics .............................................. 10
Switching Waveforms .................................................... 11
Write Cycle Timing .................................................... 11
Read Cycle Timing .................................................... 11
Reset Timing .............................................................. 12
First Data Word Latency after Reset with Read and Write 13
Document #: 38-06013 Rev. *F
Full Flag Timing ......................................................... 15
Programmable Almost Empty Flag Timing ................ 15
Programmable Almost Full Flag Timing .................... 16
Write Programmable Registers ................................. 16
Read Programmable Registers ................................. 17
Ordering Code Definition ........................................... 18
Ordering Information ...................................................... 18
Acronyms ........................................................................ 20
Document Conventions ................................................. 20
Units of Measure ....................................................... 20
Document History Page ................................................. 21
Sales, Solutions, and Legal Information ...................... 22
Worldwide Sales and Design Support ....................... 22
Products .................................................................... 22
PSoC Solutions ......................................................... 22
Page 3 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Pin Configuration
D4
D5
D6
D7
D8
4 3 2 1 32 31 30
29
28
CY7C4261V
CY7C4271V
CY7C4281V
CY7C4291V
27
26
25
24
23
22
21
14 15 16 17 18 19 20
EF
FF
Q0
Q1
Q2
REN1
RCLK
REN2
OE
5
6
7
8
9
10
11
12
13
RS
WEN1
WCLK
WEN2/LD
VCC
Q8
Q7
Q6
Q5
Q3
Q4
D1
D0
PAF
PAE
GND
D3
D2
PLCC
Top View
Pin Definitions
Pin No.
Signal Name
Description
I/O
Description
1–6, 30–32 D08
Data inputs
I
Data inputs for 9-bit bus.
1–6, 30–32 Q08
Data outputs
O
Data outputs for 9-bit bus.
28
WEN1
Write Enable 1
I
The only write enable when device is configured to have programmable flags.
Data is written on a LOW-to-HIGH transition of WCLK when WEN1 is asserted
and FF is HIGH. If the FIFO is configured to have two write enables, data is
written on a LOW-to-HIGH transition of WCLK when WEN1 is LOW and
WEN2/LD and FF are HIGH.
26
WEN2/LD
Write Enable 2
Dual mode pin
Load
I
If HIGH at reset, this pin operates as a second write enable. If LOW at reset,
this pin operates as a control to write or read the programmable flag offsets.
WEN1 must be LOW and WEN2 must be HIGH to write data into the FIFO. Data
will not be written into the FIFO if the FF is LOW. If the FIFO is configured to
have programmable flags, WEN2/LD is held LOW to write or read the
programmable flag offsets.
10, 12
REN1, REN2
Read Enable 
inputs
I
Enables the device for Read operation. Both REN1 and REN2 must be asserted
to allow a read operation.
27
WCLK
Write Clock
I
The rising edge clocks data into the FIFO when WEN1 is LOW and WEN2/LD
is HIGH and the FIFO is not full. When LD is asserted, WCLK writes data into
the programmable flag-offset register.
11
RCLK
Read Clock
I
The rising edge clocks data out of the FIFO when REN1 and REN2 are LOW
and the FIFO are not Empty. When WEN2/LD is LOW, RCLK reads data out of
the programmable flag-offset register.
14
EF
Empty Flag
O
When EF is LOW, the FIFO is empty. EF is synchronized to RCLK.
15
FF
Full Flag
O
When FF is LOW, the FIFO is full. FF is synchronized to WCLK.
8
PAE
Programmable
Almost Empty
O
When PAE is LOW, the FIFO is almost empty based on the almost empty offset
value programmed into the FIFO. PAE is synchronized to RCLK.
7
PAF
Programmable
Almost Full
O
When PAF is LOW, the FIFO is almost full based on the almost full offset value
programmed into the FIFO. PAF is synchronized to WCLK.
29
RS
Reset
I
Resets device to empty condition. A reset is required before an initial read or
write operation after power-up.
13
OE
Output Enable
I
When OE is LOW, the FIFO’s data outputs drive the bus to which they are
connected. If OE is HIGH, the FIFO’s outputs are in High Z (high-impedance)
state.
Document #: 38-06013 Rev. *F
Page 4 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Architecture
Programming
The CY7C4261/71/81/91V consists of an array of 16 K, 32 K,
64 K, or 128 K words of nine bits each (implemented by a
dual-port array of SRAM cells), a read pointer, a write pointer,
control signals (RCLK, WCLK, REN1, REN2, WEN1, WEN2,
RS), and flags (EF, PAE, PAF, FF).
When WEN2/LD is held LOW during Reset, this pin is the load
(LD) enable for flag offset programming. In this configuration,
WEN2/LD can be used to access the four 9-bit offset registers
contained in the CY7C4261/71/81/91V for writing or reading data
to these registers.
Resetting the FIFO
When the device is configured for programmable flags and both
WEN2/LD and WEN1 are LOW, the first LOW-to-HIGH transition
of WCLK writes data from the data inputs to the empty offset least
significant bit (LSB) register. The second, third, and fourth
LOW-to-HIGH transitions of WCLK store data in the empty offset
most significant bit (MSB) register, full offset LSB register, and
full offset MSB register, respectively, when WEN2/LD and WEN1
are LOW. The fifth LOW-to-HIGH transition of WCLK while
WEN2/LD and WEN1 are LOW writes data to the empty LSB
register again. Figure 1 shows the registers sizes and default
values for the various device types.
Upon power-up, the FIFO must be reset with a Reset (RS) cycle.
This causes the FIFO to enter the Empty condition signified by
EF being LOW. All data outputs (Q0–8) go LOW tRSF after the
rising edge of RS. In order for the FIFO to reset to its default
state, the user must not read or write while RS is LOW. All flags
are guaranteed to be valid tRSF after RS is taken LOW.
FIFO Operation
When the WEN1 signal is active LOW, WEN2 is active HIGH,
and FF is active HIGH, data present on the D0 –8 pins is written
into the FIFO on each rising edge of the WCLK signal. Similarly,
when the REN1 and REN2 signals are active LOW and EF is
active HIGH, data in the FIFO memory will be presented on the
Q0-8 outputs. New data will be presented on each rising edge of
RCLK while REN1 and REN2 are active. REN1 and REN2 must
set up tENS before RCLK for it to be a valid read function. WEN1
and WEN2 must occur tENS before WCLK for it to be a valid write
function.
An output enable (OE) pin is provided to three-state the Q0–8
outputs when OE is asserted. When OE is enabled (LOW), data
in the output register will be available to the Q0-8 outputs after
tOE. If devices are cascaded, the OE function will only output
data on the FIFO that is read enabled.
The FIFO contains overflow circuitry to disallow additional writes
when the FIFO is full, and underflow circuitry to disallow
additional reads when the FIFO is empty. An empty FIFO
maintains the data of the last valid read on its Q0-8 outputs even
after additional reads occur.
Write Enable 1 (WEN1). If the FIFO is configured for
programmable flags, Write Enable 1 (WEN1) is the only write
enable control pin. In this configuration, when Write Enable 1
(WEN1) is LOW, data can be loaded into the input register and
RAM array on the LOW-to-HIGH transition of every write clock
(WCLK). Data is stored is the RAM array sequentially and
independently of any on-going read operation.
Write Enable 2/Load (WEN2/LD). This is a dual-purpose pin.
The FIFO is configured at Reset to have programmable flags or
to have two write enables, which allows for depth expansion. If
Write Enable 2/Load (WEN2/LD) is set active HIGH at Reset (RS
= LOW), this pin operates as a second write enable pin.
If the FIFO is configured to have two write enables, when Write
Enable (WEN1) is LOW and Write Enable 2/Load (WEN2/LD) is
HIGH, data can be loaded into the input register and RAM array
on the LOW-to-HIGH transition of every write clock (WCLK).
Data is stored in the RAM array sequentially and independently
of any on-going read operation.
Document #: 38-06013 Rev. *F
Figure 1. Offset Register Location and Default Values
16 k x 9
8
32 k x 9
0
7
8
Empty Offset (LSB) Reg.
Default Value = 007h
8
Empty Offset (LSB) Reg.
Default Value = 007h
0
5
0
7
(MSB)
Default Value = 000h
(MSB)
Default Value = 000h
0
8 7
8
Full Offset (LSB) Reg
Default Value = 007h
0
5
(MSB)
Default Value = 000h
128k x 9
64k x 9
0
7
8
Empty Offset (LSB) Reg.
Default Value = 007h
0
0
8
(MSB)
Default Value = 000h
(MSB)
Default Value = 000h
0
8 7
8
Full Offset (LSB) Reg
Default Value = 007h
(MSB)
Default Value = 000h
0
7
Full Offset (LSB) Reg
Default Value = 007h
0
8 7
0
7
Empty Offset (LSB) Reg.
Default Value = 007h
8 7
0
6
8
(MSB)
Default Value = 000h
8
0
7
Full Offset (LSB) Reg
Default Value = 007h
8
0
6
8
0
8
(MSB)
Default Value = 000h
Page 5 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
It is not necessary to write to all the offset registers at one time.
A subset of the offset registers can be written; then by bringing
the WEN2/LD input HIGH, the FIFO is returned to normal read
and write operation. The next time WEN2/LD is brought LOW, a
write operation stores data in the next offset register in
sequence.
Table 1. Writing the Offset Registers[1]
LD
WEN
0
0
The contents of the offset registers can be read to the data
outputs when WEN2/LD is LOW and both REN1 and REN2 are
LOW. LOW-to-HIGH transitions of RCLK read register contents
to the data outputs. Writes and reads should not be performed
simultaneously on the offset registers.
0
1
No operation
Programmable Flag (PAE, PAF) Operation
1
0
Write into FIFO
1
1
No operation
Whether the flag offset registers are programmed as described
in Table 1 or the default values are used, the programmable
almost-empty flag (PAE) and programmable almost-full flag
(PAF) states are determined by their corresponding offset
registers and the difference between the read and write pointers.
WCLK
Selection
Empty offset (LSB)
Empty offset (MSB)
Full offset (LSB)
Full offset (MSB)
The number formed by the empty offset least significant bit
register and empty offset most significant bit register is referred
to as n and determines the operation of PAE. PAE is synchronized to
the LOW-to-HIGH transition of RCLK by one flip-flop and is LOW
when the FIFO contains n or fewer unread words. PAE is set
HIGH by the LOW-to-HIGH transition of RCLK when the FIFO
contains (n+1) or greater unread words.
The number formed by the full offset least significant bit register
and full offset most significant bit register is referred to as m and
determines the operation of PAF. PAF is synchronized to the
LOW-to-HIGH transition of WCLK by one flip-flop and is set LOW
when the number of unread words in the FIFO is greater than or
equal to CY7C4261V (16k – m), CY7C4271V (32k – m),
CY7C4281V (64k – m) and CY7C4291V (128k – m). PAF is set
HIGH by the LOW-to-HIGH transition of WCLK when the number
of available memory locations is greater than m.
Table 2. Status Flags
Number of Words in FIFO
CY7C4261V
CY7C4271V
CY7C4281V
CY7C4291V
FF PAF PAE EF
0
0
0
0
H
H
L
L
1 to n[2]
1 to n[2]
1 to n[2]
1 to n[2]
H
H
L
H
(n + 1) to (1638  (m + 1)) (n + 1) to (32768  (m + 1)) (n + 1) to (65536  (m + 1)) (n + 1) to (131072  (m + 1))
H
H
H
H
(16384  m)[3] to 16383
(32768  m)[3] to 32767
(65536  m)[3] to 65535
(131072  m)[3] to 131071
H
L
H
H
16384
32768
65536
131072
L
L
H
H
Notes
1. The same selection sequence applies to reading from the registers. REN1 and REN2 are enabled and a read is performed on the LOW-to-HIGH transition of RCLK.
2. n = Empty Offset (n = 7 default value).
3. m = Full Offset (m = 7 default value).
Document #: 38-06013 Rev. *F
Page 6 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Width-Expansion Configuration
Flag Operation
Word width may be increased simply by connecting the
corresponding input controls signals of multiple devices. A
composite flag should be created for each of the end-point status
flags (EF and FF). The partial status flags (PAE and PAF) can be
detected from any one device. Figure 2 demonstrates a 18-bit
word width by using two CY7C42x1Vs. Any word width can be
attained by adding additional CY7C42x1Vs.
The CY7C4261/71/81/91V devices provide five flag pins to
indicate the condition of the FIFO contents. Empty, Full, PAE,
and PAF are synchronous.
When the CY7C42x1V is in a Width-Expansion Configuration,
the Read Enable (REN2) control input can be grounded (see
Figure 2). In this configuration, the Write Enable 2/Load
(WEN2/LD) pin is set to LOW at Reset so that the pin operates
as a control to load and read the programmable flag offsets.
Full Flag
The Full Flag (FF) will go LOW when the device is full. Write
operations are inhibited whenever FF is LOW regardless of the
state of WEN1 and WEN2/LD. FF is synchronized to WCLK, i.e.,
it is exclusively updated by each rising edge of WCLK.
Empty Flag
The Empty Flag (EF) will go LOW when the device is empty.
Read operations are inhibited whenever EF is LOW, regardless
of the state of REN1 and REN2. EF is synchronized to RCLK,
i.e., it is exclusively updated by each rising edge of RCLK.
Figure 2. Block Diagram of 16 K / 32 K / 64 K / 128 K × 9 Low-Voltage Deep Sync FIFO Memory
Used in a Width-Expansion Configuration
Reset (RS)
Data In (D)
18
Reset (RS)
9
9
Read Clock
Write Clock (WLCK)
Read Enable 1 (REN1)
Write Enable (WEN1)
Write Enable 2/Load
(WEN2/LD)
Output
CY7C4261V
CY7C4271V
CY7C4281V
CY7C4291V
Programmable (PAF)
Full
Flag (FF) # 1
Full
Flag (FF) # 2
(RCLK)
FF
CY7C4261V
CY7C4271V
CY7C4281V
CY7C4291V
FF
EF
Enable
(OE)
Programmable
(PAE)
Empty Flag (EF) #1
Empty Flag (EF) #2
EF
9
Data Out (Q)
18
9
Read Enable 2 (REN2)
Document #: 38-06013 Rev. *F
Read Enable 2 (REN2)
Page 7 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Maximum Ratings
Output current into outputs (LOW) .............................. 20 mA
Static discharge voltage........................................... > 2001 V
(per MIL-STD-883, Method 3015)
Latch-up current ..................................................... > 200 mA
(Exceeding maximum ratings may shorten the useful life of the
device. User guidelines are not tested.)
Storage temperature .................................. –65 °C to +150 °C
Ambient temperature with power applied ... –55 °C to +125 °C
Supply voltage to ground potential ...............–0.5 V to +3.6 V
DC voltage applied to outputs
in High-Z state ..................................... –0.5 V to VCC + 0.5 V
DC input voltage .................................. –0.5 V to VCC + 0.5 V
Operating Range
Range
Ambient Temperature
VCC[4]
Commercial
0 °C to +70 °C
3.3 V 300 mV
40 °C to +85 °C
3.3 V 300 mV
Industrial
Electrical Characteristics Over the Operating Range
Parameter
Description
Test Conditions
VOH
Output HIGH
voltage
VCC = Min., IOH = 1.0 mA
VCC = 3.0 V, IOH = 2.0 mA
VOL
Output LOW
voltage
VCC = Min., IOL = 4.0 mA
VCC = 3.0 V, IOL = 8.0 mA
VIH
Input HIGH
voltage
VIL
7C4261/71/81/91V- 7C4261/71/81/91V- 7C4261/71/81/91V10
15
25
Unit
Min
Max
Min
Max
Min
Max
2.4
–
2.4
–
2.4
–
V
–
.04
–
0.4
–
0.4
V
–
2.0
VCC
2.0
VCC
2.0
VCC
V
Input LOW
voltage
–
0.5
0.8
0.5
0.8
0.5
0.8
V
IIX
Input leakage
current
VCC = Max.
10
+10
10
+10
10
+10
A
IOZL
IOZH
Output OFF,
High Z current
OE VIH, 
VSS < VO< VCC
10
+10
10
+10
10
+10
A
ICC1[5]
Active power
supply current
–
Com’l
–
25
–
25
–
25
mA
Ind
–
–
–
30
–
–
mA
Com’l
–
4
–
4
–
4
mA
Ind
–
–
–
4
–
–
mA
ISB[6]
Average
–
standby current
Capacitance
Parameter[7]
Description
CIN
Input capacitance
COUT
Output capacitance
Test Conditions
TA = 25 C, f = 1 MHz,
VCC = 3.3 V
Max
Unit
5
pF
7
pF
Notes
4. VCC Range for commercial –10 ns is 3.3 V ±150 mV.
5. Input signals switch from 0 V to 3 V with a rise/fall time of less than 3 ns, clocks and clock enables switch at maximum frequency of 20 MHz, while data inputs switch
at 10 MHz. Outputs are unloaded.
6. All inputs = VCC – 0.2 V, except WCLK and RCLK (which are at frequency = 0 MHz). All outputs are unloaded.
7. Tested initially and after any design or process changes that may affect these parameters.
Document #: 38-06013 Rev. *F
Page 8 of 22
[+] Feedback
CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
AC Test Loads and Waveforms (-15 and -25)[8, 9]
R1 = 330 
All Input Pulses
3.3 V
Output
3.0 V
CL
Equivalent to:
R2=510 
Including
JIG and
Scope
Thé venin Equivalent
200 
Output
90%
10%
GND
 3 ns
90%
10%
 3 ns
2.0 V
AC Test Loads and Waveforms (-10)
VCC/2
All Input Pulses
50
3.0V
I/O
Z0 = 50
90%
10%
GND
 3 ns
90%
10%
 3 ns
Notes
8. CL = 30 pF for all AC parameters except for tOHZ.
9. CL = 5 pF for tOHZ.
Document #: 38-06013 Rev. *F
Page 9 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Switching Characteristics Over the Operating Range
Parameter
7C4261/71/81/91V- 7C4261/71/81/91V- 7C4261/71/81/91V10
15
25
Description
Unit
Min
Max
Min
Max
Min
Max
–
100
–
66.7
–
40
MHz
tS
Clock cycle frequency
tA
Data access time
2
8
2
10
2
15
ns
tCLK
Clock cycle time
10
–
15
–
25
–
ns
tCLKH
Clock HIGH time
4.5
–
6
–
10
–
ns
tCLKL
Clock LOW time
4.5
–
6
–
10
–
ns
tDS
Data set-up time
3.5
–
4
–
6
–
ns
tDH
Data hold time
0
–
0
–
1
–
ns
tENS
Enable set-up time
3.5
–
4
–
6
–
ns
tENH
Enable hold time
0
–
0
–
1
–
ns
width[10]
tRS
Reset pulse
10
–
15
–
25
–
ns
tRSS
Reset set-up time
8
–
10
–
15
–
ns
tRSR
Reset recovery time
8
–
10
–
15
–
ns
tRSF
Reset to flag and output time
–
10
–
15
–
25
ns
0
–
0
–
0
–
ns
3
7
3
10
3
12
ns
tOLZ
Output enable to output in Low
tOE
Output enable to output valid
Z[10]
Z[11]
tOHZ
Output enable to output in High
3
7
3
8
3
12
ns
tWFF
Write clock to Full flag
–
8
–
10
–
15
ns
tREF
Read clock to Empty flag
–
8
–
10
–
15
ns
tPAF
Clock to programmable Almost-Full flag
–
8
–
10
–
15
ns
tPAE
Clock to programmable Almost-Full flag
–
8
–
10
–
15
ns
tSKEW1
Skew time between read clock and write
clock for Empty flag and Full flag
5
–
6
–
10
–
ns
tSKEW2
Skew time between read clock and write
clock for Almost-Empty flag and Almost-Full
flag
10
–
15
–
18
–
ns
Notes
10. Pulse widths less than minimum values are not allowed.
11. Values guaranteed by design, not currently tested.
Document #: 38-06013 Rev. *F
Page 10 of 22
[+] Feedback
CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Switching Waveforms
Write Cycle Timing
tCLK
tCLKH
tCLKL
WCLK
tDS
tDH
D0 –D17
tENS
tENH
WEN1
No Operation
No Operation
WEN2
(if applicable)
tWFF
tWFF
FF
tSKEW1 [12]
RCLK
REN1, REN2
Read Cycle Timing
tCKL
tCLKH
tCLKL
RCLK
tENS
tENH
REN1, REN2
NO OPERATION
tREF
tREF
EF
tA
Q0 –Q17
Valid Data
tOLZ
tOHZ
tOE
OE
tSKEW1[13]
WCLK
WEN1
WEN2
Notes
12. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF will go HIGH during the current clock cycle. If the time
between the rising edge of RCLK and the rising edge of WCLK is less than tSKEW1, then FF may not change state until the next WCLK rising edge.
13. tSKEW1 is the minimum time between a rising WCLK edge and a rising RCLK edge to guarantee that EF will go HIGH during the current clock cycle. It the time
between the rising edge of WCLK and the rising edge of RCLK is less than tSKEW2, then EF may not change state until the next RCLK rising edge.
Document #: 38-06013 Rev. *F
Page 11 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Switching Waveforms
(continued)
Reset Timing[14]
RS
tRS
tRSS
tRSR
tRSS
tRSR
tRSS
tRSR
REN1,
REN2
WEN1
WEN2/LD
[16]
tRSF
EF,PAE
tRSF
FF, PAF
tRSF
Q0  Q8
[15]
OE = 1
OE=0
Notes
14. The clocks (RCLK, WCLK) can be free-running during reset.
15. After reset, the outputs will be LOW if OE = 0 and three-state if OE = 1.
16. Holding WEN2/LD HIGH during reset will make the pin act as a second enable pin. Holding WEN2/LD LOW during reset will make the pin act as a load enable
for the programmable flag offset registers.
Document #: 38-06013 Rev. *F
Page 12 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Switching Waveforms
(continued)
First Data Word Latency after Reset with Read and Write
WCLK
tDS
D0 –D8
D0
D1
(First Valid Write)
D2
D3
D4
tENS
tFRL [17]
WEN1
WEN2
(if applicable)
tSKEW1
RCLK
tREF
EF
tA
tA [18]
REN1,
REN2
Q0 –Q8
D0
tOLZ
D1
tOE
OE
Notes
17. When tSKEW1 > minimum specification, tFRL (maximum) = tCLK + tSKEW2. When tSKEW1 < minimum specification, tFRL (maximum) = either 2*tCLK + tSKEW1 or tCLK
+ tSKEW1. The Latency Timing applies only at the Empty Boundary (EF = LOW).
18. The first word is available the cycle after EF goes HIGH, always.
Document #: 38-06013 Rev. *F
Page 13 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Switching Waveforms
(continued)
Empty Flag Timing
WCLK
tDS
tDS
Data Write 2
Data Write 1
D0 –D8
tENS
tENH
tENH
tENS
WEN1
tENS
tENH
tENS
tENH
WEN2
(if applicable)
tFRL [19]
tFRL [19]
RCLK
tSKEW1
tREF
tREF
tREF
tSKEW1
EF
REN1,
REN2
LOW
OE
tA
Q0 –Q8
Data In Output Register
Data Read
Note
19. When tSKEW1 > minimum specification, tFRL (maximum) = tCLK + tSKEW2. When tSKEW1 < minimum specification, tFRL (maximum) = either 2*tCLK + tSKEW1 or tCLK
+ tSKEW1. The Latency Timing applies only at the Empty Boundary (EF = LOW).
Document #: 38-06013 Rev. *F
Page 14 of 22
[+] Feedback
CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Switching Waveforms
(continued)
Full Flag Timing
No Write
No Write
WCLK
tSKEW1[20]
tSKEW1[20]
tDS
Data Write
Data Write
D0 –D8
tWFF
tWFF
tWFF
FF
WEN1
WEN2
(if applicable)
RCLK
OE
tENH
tENS
REN1,
REN2
tENS
LOW
tA
Q0 –Q8
tENH
tA
Data Read
Data In Output Register
Next Data Read
Programmable Almost Empty Flag Timing
tCLKL
tCLKH
WCLK
tENS tENH
WEN1
WEN2
(if applicable)
22
tENS tENH
PAE
N + 1 WORDS
IN FIFO
tSKEW2 [21]
tPAE
23
tPAE
RCLK
tENS
tENS tENH
REN1,
REN2
Notes
20. tSKEW1 is the minimum time between a rising RCLK edge and a rising WCLK edge to guarantee that FF will go HIGH during the current clock cycle. If the time
between the rising edge of RCLK and the rising edge of WCLK is less than tSKEW1, then FF may not change state until the next WCLK rising edge.
21. tSKEW2 is the minimum time between a rising WCLK and a rising RCLK edge for PAE to change state during that clock cycle. If the time between the edge of
WCLK and the rising RCLK is less than tSKEW2, then PAE may not change state until the next RCLK.
22. PAE offset = n.
23. If a read is performed on this rising edge of the read clock, there will be Empty + (n1) words in the FIFO when PAE goes LOW.
Document #: 38-06013 Rev. *F
Page 15 of 22
[+] Feedback
CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Switching Waveforms
(continued)
Programmable Almost Full Flag Timing
tCLKL
tCLKH
Note 24
WCLK
tENS tENH
WEN1
Note 25
WEN2
(if applicable)
tPAF
tENS tENH
PAF
(Full - M) Words
In FIFO [26]
Full (M+1) Words
In FIFO
tSKEW2 [27]
tPAF
RCLK
tENS
tENS tENH
REN1,
REN2
Write Programmable Registers
tCLK
tCLKL
tCLKH
WCLK
tENS
tENH
WEN2/LD
tENS
WEN1
tDS
tDH
D0 –D8
PAE Offset
LSB
PAE Offset
MSB
PAF Offset
LSB
PAF Offset
MSB
Notes
24. If a write is performed on this rising edge of the write clock, there will be Full  (m1) words of the FIFO when PAF goes LOW.
25. PAF offset = m.
26. 16 K m words for CY7C4261V, 32 K – m words for CY7C4271V, 64 K  m words for CY7C4281V, and 128 K  m words for CY4291V.
27. tSKEW2 is the minimum time between a rising RCLK edge and a rising WCLK edge for PAF to change during that clock cycle. If the time between the rising edge
of RCLK and the rising edge of WCLK is less than tSKEW2, then PAF may not change state until the next WCLK.
Document #: 38-06013 Rev. *F
Page 16 of 22
[+] Feedback
CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Switching Waveforms
(continued)
Read Programmable Registers
tCLK
tCLKL
tCLKH
RCLK
tENS
tENH
WEN2/LD
tENS
PAF Offset
MSB
REN1,
REN2
tA
Q0 –Q15
Document #: 38-06013 Rev. *F
Unknown
PAE Offset LSB
PAE Offset MSB
PAF Offset
LSB
Page 17 of 22
[+] Feedback
CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Ordering Information
16 K × 9 Low-Voltage Deep Sync FIFO
Speed (ns)
Ordering Code
10
CY7C4261V-10JXC
15
CY7C4261V-15JXC
Package Name
Package Type
Operating Range
J65
32-pin Pb-free plastic leaded chip carrier
Commercial
J65
32-pin Pb-free plastic leaded chip carrier
Commercial
32 K × 9 Low-Voltage Deep Sync FIFO
10
CY7C4271V-10JXC
J65
32-pin Pb-free plastic leaded chip carrier
Commercial
64 K × 9 Low-Voltage Deep Sync FIFO
10
CY7C4281V-10JXC
J65
32-pin Pb-free plastic leaded chip carrier
Commercial
128 K × 9 Low-Voltage Deep Sync FIFO
10
CY7C4291V-10JXC
J65
32-pin Pb-free plastic leaded chip carrier
Commercial
15
CY7C4291V-15JXC
J65
32-pin Pb-free plastic leaded chip carrier
Commercial
Ordering Code Definition
CY 7 C
42xx
V
-
xx
JXC
Package Type: 
J = Package name, X = Pb-free, C = Commercial
Speed: 10/15 ns
Separator
Voltage: 3.3 V
Part Identifier
Technology: CMOS
Marketing Code: 7 = SRAM
Company ID: CY = Cypress
Document #: 38-06013 Rev. *F
Page 18 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Package Diagram
Figure 3. 32-Pin Pb-free Plastic Leaded Chip Carrier J65, 51-85002
51-85002 *C
Document #: 38-06013 Rev. *F
Page 19 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Acronyms
Document Conventions
Table 3. Acronyms Used
Units of Measure
Acronym
Description
Table 4. Units of Measure
CMOS
complementary metal oxide semiconductor
CE
chip enable
ns
nano seconds
I/O
input/output
V
volts
OE
output enable
µA
micro amperes
SRAM
static random access memory
mA
milli amperes
TSOP
thin small outline package
pF
pico Farad
WE
write enable
°C
degree Celsius
W
watts
Document #: 38-06013 Rev. *F
Symbol
Unit of Measure
Page 20 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Document History Page
Document Title: CY7C4261V/CY7C4271V/CY7C4281V/CY7C4291V 16 K / 32 K / 64 K / 128 K × 9 Low-Voltage Deep Sync™ FIFOs
Document Number: 38-06013
REV.
ECN NO.
Issue Date
Orig. of
Change
Description of Change
**
106474
09/15/01
SZV
Changed Spec number from 38-00656 to 38-06013
*A
127858
09/04/03
FSG
Changed: tSKEW2 to tSKEW1 in Switching Waveforms “Empty Flag Timing” diagram
Fixed flag timing diagram in Switching Waveforms section
*B
386127
See ECN
ESH
Added Pb-Free logo to top of front page
Added CY7C4291V-15JXC, CY7C91V-10JXC, CY7C4281V-10JXC,
CY7C4271V-10JXC, CY7C4261V-10JXC, CY7C4261V-15JXC to ordering information.
*C
2896378
03/19/2010
RAME
Removed inactive parts from Ordering information and updated package diagram.
*D
2906525
04/07/2010
RAME
Removed inactive part from Ordering Information table.
*E
3069396
10/22/2010
ADMU
Corrected data in Programmable Flag (PAE, PAF) Operation:
a) PAF is synchronized to the LOW-to-HIGH transition of RCLK by one flip-flop and
is LOW when the FIFO contains n or fewer unread words. Changed PAF to PAE.
b) PAE is synchronized to the LOW-to-HIGH transition of WCLK by one flip-flop and
is set LOW when the number of unread words in the FIFO is greater than or equal
to CY7C4261 (16K-m) and CY7C4271 (32K-m). Changed PAE to PAF.
Added Acronyms, Document Conventions, and Ordering Code Definition.
*F
3210221
03/25/2011
ADMU
Removed CY7C4271V-10JC part from Ordering Information table.
Document #: 38-06013 Rev. *F
Page 21 of 22
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CY7C4261V/CY7C4271V
CY7C4281V/CY7C4291V
Sales, Solutions, and Legal Information
Worldwide Sales and Design Support
Cypress maintains a worldwide network of offices, solution centers, manufacturer’s representatives, and distributors. To find the office
closest to you, visit us at Cypress Locations.
Products
Automotive
Clocks & Buffers
Interface
Lighting & Power Control
PSoC Solutions
cypress.com/go/automotive
cypress.com/go/clocks
psoc.cypress.com/solutions
cypress.com/go/interface
PSoC 1 | PSoC 3 | PSoC 5
cypress.com/go/powerpsoc
cypress.com/go/plc
Memory
Optical & Image Sensing
PSoC
Touch Sensing
USB Controllers
Wireless/RF
cypress.com/go/memory
cypress.com/go/image
cypress.com/go/psoc
cypress.com/go/touch
cypress.com/go/USB
cypress.com/go/wireless
© Cypress Semiconductor Corporation, 2005-2011. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of
any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used for
medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for use as
critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in life-support systems
application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Any Source Code (software and/or firmware) is owned by Cypress Semiconductor Corporation (Cypress) and is protected by and subject to worldwide patent protection (United States and foreign),
United States copyright laws and international treaty provisions. Cypress hereby grants to licensee a personal, non-exclusive, non-transferable license to copy, use, modify, create derivative works of,
and compile the Cypress Source Code and derivative works for the sole purpose of creating custom software and or firmware in support of licensee product to be used only in conjunction with a Cypress
integrated circuit as specified in the applicable agreement. Any reproduction, modification, translation, compilation, or representation of this Source Code except as specified above is prohibited without
the express written permission of Cypress.
Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress reserves the right to make changes without further notice to the materials described herein. Cypress does not
assume any liability arising out of the application or use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in life-support systems where
a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems application implies that the manufacturer
assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.
Document #: 38-06013 Rev. *F
Revised March 30, 2011
Page 22 of 22
Deep Sync is a trademark of Cypress Semiconductor. All product and company names mentioned in this document are the trademarks of their respective holders. All products and company names
mentioned in this document may be the trademarks of their respective holders.
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