PRELIMINARY
CY7C43624
CY7C43634/CY7C43644
CY7C43664/CY7C43684
256/512/1K/4K/16K x36 x2 Bidirectional
Synchronous FIFO w/ Bus Matching
Features
• High-speed, low-power, bidirectional, first-in first-out
(FIFO) memories w/ bus matching capabilities
• 256x36x2 (CY7C43624)
• 512x36x2 (CY7C43634)
• 1Kx36x2 (CY7C43644)
• 4Kx36x2 (CY7C43664)
• 16Kx36x2 (CY7C43684)
• 0.35-micron CMOS for optimum speed/power
• High-speed 83-MHz operation (12 ns read/write cycle
times)
• Low power
— I
CC
= 100 mA
— I
SB
= 5 mA
• Fully asynchronous and simultaneous read and write
operation permitted
• Mailbox bypass register for each FIFO
• Parallel and Serial Programmable Almost-Full and Al-
most-Empty flags
• Retransmit function
• Standard or FWFT mode user selectable
• Partial Reset
• Big or little Endian format for word or byte bus sizes
• 128-pin TQFP packaging
• Pin-compatible, feature enhanced, density upgrade to
IDT723624/34/44 family
• Easily expandable in width and depth
Logic Block Diagram
MBF1
CLKA
CSA
W/RA
ENA
MBA
RT2
Input
Register
Register
MRS1
PRS1
FIFO1,
Mail 1
Reset
Logic
Write
Pointer
Read
Pointer
FFA/IRA
AFA
Status
Flag Logic
Output
256/512/1K
4K/16K x36
Dual Ported
Memory
Bus Matching
Port-A
Control
Logic
Mail 1
Register
CLKB
CSB
W/RB
ENB
MBB
RTI
BE
BM
SIZE
Port-B
Control
Logic
EFB/ORB
AEB
SPM
FS0/SD
FS1/SEN
A
0–35
EFA/ORA
AEA
Programmable Flag
Offset Registers
Timing
Mode
36
B
0–35
BE/FWFT
36
Status
Flag Logic
Write
Pointer
Read
Pointer
FFB/IRB
AFB
Output
Register
256/512/1K
4K/16K x36
Dual Ported
Memory
Mail 2
Register
MBF2
Cypress Semiconductor Corporation
•
3901 North First Street
•
San Jose
Input
Register
FIFO1,
Mail 1
Reset
Logic
MRS2
PRS2
•
CA 95134
•
408-943-2600
October 6, 1998
PRELIMINARY
Pin Configuration
CY7C43624
CY7C43634/CY7C43644
CY7C43664/CY7C43684
TQFP
Top View
CSA
FFA/IRA
EFA/ORA
PRS1
V
CC
AFA
AEA
MBF2
MBA
MRS1
FS0/SD
GND
GND
FS1/SEN
MRS2
MBB
EFB/ORB
FFB/IRB
GND
CSB
W/RB
ENB
102
101
100
99
98
97
96
95
94
93
92
91
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
W/RA
ENA
CLKA
GND
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
BE/FWFT
GND
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
GND
A
11
A
10
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
31
32
33
34
35
36
37
38
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
MBF1
V
CC
AEB
AFB
CLKB
PRS2
V
CC
B
35
B
34
B
33
B
32
GND
GND
B
31
B
30
B
29
B
28
B
27
B
26
RT1
B
25
B
24
BM
GND
B
23
B
22
B
21
B
20
B
19
B
18
GND
B
17
B
16
SIZE
V
CC
B
15
B
14
B
13
B
12
GND
B
11
B
10
CY7C43624
CY7C43634
CY7C43644
CY7C43664
CY7C43684
A
9
A
8
A
7
A
6
GND
A
5
A
4
A
3
SPM
V
CC
A
2
A
1
A
0
GND
B
0
B
1
B
2
B
3
B
4
B
5
2
GND
B
6
V
CC
B
7
B
8
B
9
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
PRELIMINARY
Functional Description
The CY7C436X4 is a monolithic, high-speed, low-power,
CMOS Bidirectional Synchronous (clocked) FIFO memory
which supports clock frequencies up to 83 MHz and has read
access times as fast as 9 ns. Two independent
256/512/1K/4K/16K x 36 dual-port SRAM FIFOs on board
each chip buffer data in opposite directions. FIFO data on Port
B can be input and output in 36-bit, 18-bit, or 9-bit formats with
a choice of big- or little-endian configurations.
The CY7C436X4 is a synchronous (clocked) FIFO, meaning
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 in-
dependent of one another and can be asynchronous or coin-
cident. The enables for each port are arranged to provide a
simple bidirectional interface between microprocessors 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.
Two kinds of reset are available on the CY7C436X4: Master
Reset and Partial Reset. Master Reset initializes the read and
write pointers to the first location of the memory array, config-
ures the FIFO for big- or little-endian byte arrangement and
selects serial flag programming, 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,
MRS1 and MRS2.
Partial Reset also sets the read and write pointers to the first
location of the memory. Unlike Master Reset, any settings ex-
isting prior to Partial Reset (i.e., programming method and par-
tial flag default offsets) are retained. Partial Reset is useful
since it permits flushing of the FIFO memory without changing
any configuration settings. Each FIFO has its own, indepen-
dent Partial Reset pin, PRS1 and PRS2.
The CY7C436X4 have two modes of operation: In the CY
Standard Mode, the first word written to an empty FIFO is de-
posited into the memory array. A read operation is required to
access that word (along with all other words residing in mem-
ory). In the First Word Fall Through Mode (FWFT), the first
CY7C43624
CY7C43634/CY7C43644
CY7C43664/CY7C43684
long-word (36-bit wide) written to an empty FIFO appears au-
tomatically on the outputs, no read operation required (never-
theless, accessing subsequent words does necessitate a for-
mal read request). The state of the BE/FWFT 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. 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 writ-
ten to FIFO memory achieve a predetermined “almost empty
state.” AFA and AFB indicate when a selected number of
words written to the memory achieve a predetermined “almost
full state.”
IRA, IRB, AFA, and AFB are synchronized to the port clock that
writes data into its array. ORA, ORB, AEA, and AEB are syn-
chronized to the port clock that reads data from its array. Pro-
grammable offset for AEA, AEB, AFA, and AFB are loaded in
parallel using Port A or in serial via the SD input. 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. If at any time, the FIFO is not actively performing
a function, the chip will automatically power down. During the
power-down state, supply current consumption (I
CC
) is at a
minimum. Initiating any operation (by activating control inputs)
will immediately take the device out of the power-down state.
Retransmit feature is available on these devices.
The CY7C436X4 are characterized for operation from 0
°
C to
70
°
C. Input ESD protection is greater than 2001V, and latch-up
is prevented by the use of guard rings.
Selection Guide
CY7C43624/34/44/64/84–12
Maximum Frequency (MHz)
Maximum Access Time (ns)
Minimum Cycle Time (ns)
Minimum Data or Enable Set-Up (ns)
Minimum Data or Enable Hold (ns)
Maximum Flag Delay (ns)
Active Power Supply
Current (I
CC1
) (mA)
Commercial
Industrial
CY7C43624
Density
Package
256 x 36 x2
128 TQFP
CY7C43634
512 x 36 x2
128 TQFP
83
9
12
4
0
8
100
100
CY7C43644
1K x 36 x2
128 TQFP
CY7C43664
4K x 36 x2
128 TQFP
CY7C43624/34/44/64/84−15
66.7
10
15
5
0
8
100
100
CY7C43684
16K x 36 x2
128 TQFP
3
PRELIMINARY
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
Big Endian/First
Word Fall
Through Select
I/O
I/O
O
CY7C43624
CY7C43634/CY7C43644
CY7C43664/CY7C43684
Function
36-bit bidirectional data port for side A.
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.
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.
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.
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.
36-bit bidirectional data port for side B.
This is a dual-purpose pin. During Master Reset, a HIGH on BE will select Big Endian
operation. In this case, depending on the bus size, the most significant byte or word on
Port A is read from Port B first (A-to-B data flow) or written to Port B first (B-to-A data
flow). A LOW on BE will select Little Endian operation. In this case, the least significant
byte or word on Port A is read from Port B first (for A-to-B data flow) or written to Port
B first (B-to-A data flow). After Master Reset, this pin selects the timing mode. 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 must be static throughout
device operation.
A HIGH on this pin enables either byte or word bus width on Port B, depending on the
state of SIZE. A LOW selects long word operation. BM works with SIZE and BE to
select the bus size and endian arrangement for Port B. The level of BM must be static
throughout device operation.
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, avail-
able for reading. FFA/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, avail-
able for reading. FFB/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.
AEB
O
AFA
O
AFB
O
B
0–35
BE/FWFT
I/O
I
BM
Bus Match
Select (Port A)
I
CLKA
Port A Clock
I
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
4
PRELIMINARY
Pin Definitions
(continued)
Signal Name
FFB/IRB
Description
Port B Full/Input
Ready Flag
I/O
O
CY7C43624
CY7C43634/CY7C43644
CY7C43664/CY7C43684
Function
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.
FS1/SEN and FS0/SD are dual-purpose inputs used for flag offset register program-
ming. During Master Reset, FS1/SEN and FS0/SD, together with SPM, select the flag
offset programming method. Three offset register programming methods are available:
automatically load one of three preset values (8, 16, or 64), parallel load from Port A,
and serial load. When serial load is selected for flag offset register programming,
FS1/SEN is used as an enable synchronous to the LOW-to-HIGH transition of CLKA.
When FS1/SEN is LOW, a rising edge on CLKA load the bit present on FS0/SD into
the X and Y registers. The number of bit writes required to program the offset registers
is 32 for the CY7C43624, 36 for the CY7C43634, 40 for the CY7C43644, 48 for the
CY7C43664, and 56 for the CY7C43684. The first bit write stores the Y-register MSB
and the last bit write stores the X-register LSB.
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 MRS1 selects
the programming method (serial or parallel) and one of three programmable flag default
offsets for FIFO1. It also configures Port B for bus size and endian arrangement. Four
LOW-to-HIGH transitions of CLKA and four LOW-to-HIGH transitions of CLKB must
occur while MRS1 is LOW.
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 MRS2 selects
one of three programmable flag default offsets for FIFO2. Four LOW-to-HIGH transi-
tions of CLKA and four LOW-to-HIGH transitions of CLKB must occur while MRS2 is
LOW.
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. During Partial Reset, the
currently selected bus size, endian arrangement, programming method (serial or par-
allel), and programmable flag settings are all retained.
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. During Partial Reset, the
currently selected bus size, endian arrangement, programming method (serial or par-
allel), and programmable flag settings are all retained.
A LOW strobe on this pin will retransmit data on FIFO1 from the location of the write
pointer at the last Partial or Master reset.
A LOW strobe on this pin will retransmit data on FIFO2 from the location of the write
pointer at the last Partial or Master reset.
A HIGH on this pin when BM is HIGH selects byte bus (9-bit) size on Port B. A LOW
on this pin when BM is HIGH selects word (18-bit) bus size. SIZE works with BM and
BE to select the bus size and endian arrangement for Port B. The level of SIZE must
be static throughout device operation.
FS1/SEN
Flag Offset
Select 1/Serial
Enable
Flag Offset
Select 0/Serial
Data
I
FS0/SD
I
MBA
Port A Mailbox
Select
Port B Mailbox
Select
Mail1 Register
Flag
I
MBB
I
MBF1
O
MBF2
Mail2 Register
Flag
O
MRS1
FIFO1 Master
Reset
I
MRS2
FIFO2 Master
Reset
I
PRS1
FIFO1 Partial
Reset
I
PRS2
FIFO2 Partial
Reset
I
RT1
RT2
SIZE
Retransmit
FIFO1
Retransmit
FIFO2
Bus Size Select
I
I
I
5
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