Fully asynchronous and simultaneous Read and Write
operations permitted
Mailbox bypass register for each FIFO
Parallel Programmable Almost Full and Almost Empty
flags
Retransmit function
Standard or FWFT user-selectable mode
120-pin TQFP package
Easily expandable in width and depth
Logic Block Diagram
MBF1
CLKA
CSA
W/RA
ENA
MBA
RT2
Port A
Control
Logic
Input
Register
Mail1
Register
1K/4K/16K
× 36
Dual Ported
Memory
(FIFO1)
CLKB
CSB
W/RB
ENB
MBB
RT1
Register
MRST1
FIFO1,
Mail1
Reset
Logic
Write
Pointer
Read
Pointer
FFA/IRA
AFA
Status
Flag Logic
Output
Port B
Control
Logic
EFB/ORB
AEB
FS0
FS1
A
0–35
EFA/ORA
AEA
Programmable
Flag Offset
Registers
Timing
Mode
B
0–35
FWFT/STAN
Status
Flag Logic
Write
Pointer
Read
Pointer
FFB/IRB
AFB
1K/4K/16K
× 36
Dual Ported
Memory
(FIFo2)
Mail2
Register
MBF2
Cypress Semiconductor Corporation
Document #: 38-06020 Rev. *C
Output
Register
•
3901 North First Street
•
San Jose
Input
Register
FIFO2,
Mail2
Reset
Logic
MRST2
•
CA 95134 • 408-943-2600
Revised December 26, 2002
CY7C43642AV
CY7C43662AV
CY7C43682AV
Pin Configuration
TQFP
Top View
GND
CLKA
ENA
W/RA
CSA
FFA/IRA
EFA/ORA
V
CC
AFA
AEA
MBF2
MBA
MRST1
FS0
GND
FS1
AEB
AFB
EFB/ORB
FFB/IRB
GND
CSB
W/RB
ENB
CLKB
V
CC
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
64
63
62
61
MRST2
MBB
MBF1
V
CC
A
35
A
34
A
33
A
32
V
CC
A
31
A
30
GND
A
29
A
28
A
27
A
26
A
25
A
24
A
23
FWFT/STAN
A
22
V
CC
A
21
A
20
A
19
A
18
GND
A
17
A
16
A
15
A
14
A
13
RT2
A
12
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
102
101
100
99
98
97
96
95
94
93
92
91
B
35
B
34
B
33
B
32
GND
B
31
B
30
B
29
B
28
B
27
B
26
RT1
B
25
B
24
GND
B
23
B
22
B
21
B
20
B
19
B
18
GND
B
17
B
16
V
CC
B
15
B
14
B
13
B
12
GND
CY7C43642AV
CY7C43662AV
CY7C43682AV
A
8
A
7
A
6
GND
A
5
A
4
A
3
V
CC
A
2
A
1
A
0
GND
Selection Guide
CY7C43642/
62/82AV
–7
Maximum Frequency
Maximum Access Time
Minimum Cycle Time
Minimum Data or Enable Set-Up
Minimum Data or Enable Hold
Maximum Flag Delay
Active Power Supply
Current (I
CC1
)
Commercial
Industrial
CY7C43642AV
Density
Package
1K × 36 ×2
120 TQFP
CY7C43662AV
4K × 36 ×2
120 TQFP
133
6
7.5
3
0
6
60
CY7C43642/
62/82AV
–10
100
8
10
4
0
8
60
CY7C43642/
62/82AV
–15
66.7
10
15
5
0
10
60
60
CY7C43682AV
16K × 36 ×2
120 TQFP
Unit
MHz
ns
ns
ns
ns
ns
mA
mA
Document #: 38-06020 Rev. *C
B
4
B
5
GND
B
6
V
CC
B
7
B
8
B
9
B
10
B
11
GND
A
11
A
10
A
9
B
0
B
1
B
2
B
3
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Page 2 of 30
CY7C43642AV
CY7C43662AV
CY7C43682AV
Functional Description
The CY7C436X2AV is a monolithic, high-speed, low-power,
CMOS Bidirectional Synchronous FIFO memory that supports
clock frequencies up to 133 MHz and has Read access times
as fast as 6 ns. Two independent 1K/4K/16K × 36 dual-port
SRAM FIFOs on board each chip buffer data in opposite direc-
tions.
The CY7C436X2AV is a synchronous (clocked) FIFO,
meaning that each port employs a synchronous interface. All
data transfers through a port are gated to the LOW-to-HIGH
transition of a port clock by enable signals. The clocks for each
port are independent of one another and can be asynchronous
or coincident. The enables for each port are arranged to
provide a simple bidirectional interface between micropro-
cessors and/or buses with synchronous control.
Communication between each port may bypass the FIFOs via
two mailbox registers. The mailbox registers’ width matches
the selected Port B bus width. Each mailbox register has a flag
(MBF1 and MBF2) to signal when new mail has been stored.
Master Reset initializes the Read and Write pointers to the first
location of the memory array, and selects parallel flag
programming, or one of the three possible default flag offset
settings, 8, 16, or 64. Each FIFO has its own independent
Master Reset pin, MRST1 and MRST2.
The CY7C436X2AV has two modes of operation. In CY
Standard mode, the first word written to an empty FIFO is
deposited into the memory array. A Read operation is required
to access that word (along with all other words residing in
memory). In the First-Word Fall-Through mode (FWFT), the
first word (36-bit wide) written to an empty FIFO appears
automatically on the outputs, no Read operation required
(nevertheless, accessing subsequent words does necessitate
a formal Read request). The state of the FWFT/STAN pin
during FIFO operation determines the mode in use.
Each FIFO has a combined Empty/Output Ready flag
(EFA/ORA and EFB/ORB) and a combined Full/Input Ready
flag (FFA/IRA and FFB/IRB). The EF and FF functions are
selected in the CY Standard mode. EF indicates whether the
memory is full or not. FF indicates whether the FIFO is full. The
IR and OR functions are selected in the First- Word
Fall-Through mode. IR indicates whether or not the FIFO has
available memory locations. OR shows whether the FIFO has
data available for reading or not. It marks the presence of valid
data on the outputs.
Each FIFO has a programmable Almost Empty flag (AEA and
AEB) and a programmable Almost Full flag (AFA and AFB).
AEA and AEB indicate when a selected number of words
written to FIFO memory achieve a predetermined “almost
empty state.” AFA and AFB indicate when a selected number
of words written to the memory achieves a predetermined
“almost full state.”
[1]
FFA/IRA, FFB/IRB, AFA, and AFB are synchronized to the port
clock that writes data into its array. EFA/ORA, EFB/ORB, AEA,
and AEB are synchronized to the port clock that reads data
from its array. Programmable offset for AEA, AEB, AFA, and
AFB are loaded in parallel using Port A. Three default offset
settings are also provided. The AEA and AEB threshold can
be set at 8, 16, or 64 locations from the empty boundary and
AFA and AFB threshold can be set at 8, 16, or 64 locations
from the full boundary. All these choices are made using the
FS0 and FS1 inputs during Master Reset.
Two or more devices may be used in parallel to create wider
data paths.
The CY7C436X2AV FIFOs are characterized for operation
from 0°C – 70°C commercial, and from –40°C – 85°C indus-
trial. Input ESD protection is greater than 2001V, and latch-up
is prevented by the use of guard rings.
Pin Definitions
Signal Name
A
0–35
AEA
Description
Port A Data
Port A Almost
Empty Flag
Port B Almost
Empty Flag
Port A Almost
Full Flag
Port B Almost
Full Flag
Port B Data
First-Word
Fall-Through /
CY Standard
Select
I/O
O
Function
Programmable Almost Empty flag synchronized to CLKA.
It is LOW when the
number of words in FIFO2 is less than or equal to the value in the Almost Empty A offset
register, X2.
[1]
Programmable Almost Empty flag synchronized to CLKB.
It is LOW when the
number of words in FIFO1 is less than or equal to the value in the Almost Empty B offset
register, X1.
[1]
Programmable Almost Full flag synchronized to CLKA.
It is LOW when the number
of empty locations in FIFO1 is less than or equal to the value in the Almost Full A offset
register, Y1.
[1]
Programmable Almost Full flag synchronized to CLKB.
It is LOW when the number
of empty locations in FIFO2 is less than or equal to the value in the Almost Full B offset
register, Y2.
[1]
During Master Reset.
A HIGH on FWFT selects CY Standard mode, a LOW selects
First -Word Fall-Through mode. Once the timing mode has been selected, the level on
FWFT/STAN must be static throughout device operation.
I/O 36-bit bidirectional data port for side A.
AEB
O
AFA
O
AFB
O
B
0–35
FWFT/STAN
I/O 36-bit bidirectional data port for side B.
I
Note:
1. When FIFO is operated at the almost empty/full boundary, there may be an uncertainty of up to two clock cycles for flag deassertion, but the flag will always
be asserted exactly when the FIFO content reaches the programmed value. Use the assertion edge for trigger if flag accuracy is required. Refer to the Cypress
application note entitled “Designing with CY7C436xx Synchronous FIFOs” for more details on flag uncertainties.
Document #: 38-06020 Rev. *C
Page 3 of 30
CY7C43642AV
CY7C43662AV
CY7C43682AV
Pin Definitions
(continued)
Signal Name
CLKA
Description
Port A Clock
I/O
I
Function
CLKA is a continuous clock that synchronizes all data transfers through Port A and can
be asynchronous or coincident to CLKB. FFA/IRA, EFA/ORA, AFA, and AEA are all
synchronized to the LOW-to-HIGH transition of CLKA.
CLKB is a continuous clock that synchronizes all data transfers through Port B and can
be asynchronous or coincident to CLKA. FFB/IRB, EFB/ORB, AFB, and AEB are all
synchronized to the LOW-to-HIGH transition of CLKB.
CSA must be LOW to enable a LOW-to HIGH transition of CLKA to Read or Write on
Port A. The A
0–35
outputs are in the high-impedance state when CSA is HIGH.
CSB must be LOW to enable a LOW-to HIGH transition of CLKB to Read or Write on
Port B. The B
0–35
outputs are in the high-impedance state when CSB is HIGH.
This is a dual-function pin.
In the CY Standard mode, the EFA function is selected.
EFA indicates whether or not the FIFO2 memory is empty. In the FWFT mode, the ORA
function is selected. ORA indicates the presence of valid data on A
0–35
outputs available
for reading. EFA/ORA is synchronized to the LOW-to-HIGH transition of CLKA.
This is a dual-function pin.
In the CY Standard mode, the EFB function is selected.
EFB indicates whether or not the FIFO1 memory is empty. In the FWFT mode, the ORB
function is selected. ORB indicates the presence of valid data on B
0–35
outputs available
for reading. EFB/ORB is synchronized to the LOW-to-HIGH transition of CLKB.
ENA must be HIGH to enable a LOW-to-HIGH transition of CLKA to Read or Write data
on Port A.
ENB must be HIGH to enable a LOW-to-HIGH transition of CLKB to Read or Write data
on Port B.
This is a dual-function pin.
In the CY Standard mode, the FFA function is selected.
FFA indicates whether or not the FIFO1 memory is full. In the FWFT mode, the IRA
function is selected. IRA indicates whether or not there is space available for writing to
the FIFO1 memory. FFA/IRA is synchronized to the LOW-to-HIGH transition of CLKA.
This is a dual-function pin.
In the CY Standard mode, the FFB function is selected.
FFB indicates whether or not the FIFO2 memory is full. In the FWFT mode, the IRB
function is selected. IRB indicates whether or not there is space available for writing to
the FIFO2 memory. FFB/IRB is synchronized to the LOW-to-HIGH transition of CLKB.
The LOW-to-HIGH transition of a FIFO’s reset input latches the values of FS0 and FS1.
If either FS0 or FS1 is HIGH when a reset input goes HIGH, one of the three preset
values (8, 16, or 64) is selected as the offset for the FIFO’s Almost Full and Almost
Empty flags. If both FIFOs reset simultaneously and both FS0 and FS1 are LOW when
MRST1 and MRST2 go HIGH, the first four Writes program the Almost Empty and
Almost Full offsets for both FIFOs.
A HIGH level on MBA chooses a mailbox register for a Port A Read or Write operation.
When the A
0–35
outputs are active, a HIGH level on MBA selects data from the Mail2
register for output and a LOW level selects FIFO2 output register data for output.
A HIGH level on MBB chooses a mailbox register for a Port B Read or Write operation.
When the B
0–35
outputs are active, a HIGH level on MBB selects data from the Mail1
register for output and a LOW level selects FIFO1 output register data for output.
MBF1 is set LOW by a LOW-to-HIGH transition of CLKA that writes data to the Mail1
register. Writes to the Mail1 register are inhibited while MBF1 is LOW. MBF1 is set HIGH
by a LOW-to-HIGH transition of CLKB when a Port B Read is selected and MBB is HIGH.
MBF1 is set HIGH following either a Master or Partial Reset of FIFO1.
MBF2 is set LOW by a LOW-to-HIGH transition of CLKB that writes data to the Mail2
register. Writes to the Mail2 register are inhibited while MBF2 is LOW. MBF2 is set HIGH
by a LOW-to-HIGH transition of CLKA when a Port A Read is selected and MBA is HIGH.
MBF2 is set HIGH following either a Master or Partial Reset of FIFO2.
A LOW on this pin initializes the FIFO1 Read and Write pointers to the first location of
memory and sets the Port B output register to all zeroes. A LOW pulse on MRST1
selects the programming method (serial or parallel) and one of three programmable flag
default offsets for FIFO1. Four LOW-to-HIGH transitions of CLKA and four
LOW-to-HIGH transitions of CLKB must occur while MRST1 is LOW.
CLKB
Port B Clock
I
CSA
CSB
EFA/ORA
Port A Chip
Select
Port B Chip
Select
Port A Empty/
Output Ready
Flag
Port B Empty/
Output Ready
Flag
Port A Enable
Port B Enable
Port A Full/Input
Ready Flag
I
I
O
EFB/ORB
O
ENA
ENB
FFA/IRA
I
I
O
FFB/IRB
Port B Full/Input
Ready Flag
O
FS1
FS0
Flag Offset
Select 1
Flag Offset
Select 0
Port A Mailbox
Select
Port B Mailbox
Select
Mail1 Register
Flag
I
I
MBA
I
MBB
I
MBF1
O
MBF2
Mail2 Register
Flag
O
MRST1
FIFO1 Master
Reset
I
Document #: 38-06020 Rev. *C
Page 4 of 30
CY7C43642AV
CY7C43662AV
CY7C43682AV
Pin Definitions
(continued)
Signal Name
MRST2
Description
FIFO2 Master
Reset
I/O
I
Function
A LOW on this pin initializes the FIFO2 Read and Write pointers to the first location of
memory and sets the Port A output register to all zeroes. A LOW pulse on MRST2
selects one of three programmable flag default offsets for FIFO2. Four LOW-to-HIGH
transitions of CLKA and four LOW-to-HIGH transitions of CLKB must occur while
MRST2 is LOW.
A LOW strobe on this pin will retransmit the data on FIFO1. This is achieved by bringing
the Read pointer back to location zero. The user will still need to perform Read opera-
tions to retransmit the data. Retransmit function applies to CY standard mode only.
A LOW strobe on this pin will retransmit the data on FIFO2. This is achieved by bringing
the Read pointer back to location zero. The user will still need to perform Read opera-
tions to retransmit the data. Retransmit function applies to CY standard mode only.
A HIGH selects a Write operation and a LOW selects a Read operation on Port A for a
LOW-to-HIGH transition of CLKA. The A
0–35
outputs are in the high-impedance state
when W/RA is HIGH.
A LOW selects a Write operation and a HIGH selects a Read operation on Port B for a
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