CY7C451
CY7C453
CY7C454
Document #: 38-06033 Rev. *A
Page 2 of 24
Functional Description (continued)
The CY7C451, CY7C453, and CY7C454 provide three status pins
to the user. These pins are decoded to determine one of six states:
Empty, Almost Empty, Less than or Equal to Half Full, Greater than
Half Full, Almost Full, and Full (see Table 1). The Almost Empty/Full
flag (PAFE) and XO functions share the same pin. The Almost Emp-
ty/Full flag is valid in the standalone and width expansion con-
figurations. In the depth expansion, this pin provides the
expansion out (XO) information that is used to signal the
next FIFO when it will be activated.
The flags are synchronous, i.e., they change state relative to
either the read clock (CKR) or the write clock (CKW). When
entering or exiting the Empty and Almost Empty states, the
flags are updated exclusively by the CKR. The flags denoting
Half Full, Almost Full, and Full states are updated exclusively
by CKW. The synchronous flag architecture guarantees that
the flags maintain their status for some minimum time.
The CY7C451, CY7C453, and the CY7C454 use center power
and ground for reduced noise. Both configurations are fabri-
cated using an advanced RAM 2.8 technology. Input ESD
protection is greater than 2001V, and latch-up is prevented
by the use of reliable layout techniques and guard rings.
Maximum Ratings[1]
(Above which the useful life may be impaired. For user guide-
lines, not tested.)
Storage Temperature
....................................−65
°C to +150°C
Ambient Temperature with
Power Applied
.................................................−55
°C to +125°C
Supply Voltage to Ground Potential
.................−0.5V to +7.0V
DC Voltage Applied to Outputs
in High Z State
.....................................................−0.5V to +7.0V
DC Input Voltage
.................................................−3.0V to +7.0V
Output Current into Outputs (LOW)............................. 20 mA
Static Discharge Voltage............................................ >2001V
(per MIL-STD-883, Method 3015)
Latch-Up Current .................................................... > 200 mA
Notes:
1.
The Voltage on any input or I/O pin cannot exceed the power pin during
power-up.
Selection Guide
7C451-12
7C453-12
7C454-12
7C451-14
7C453-14
7C454-14
7C451-20
7C453-20
7C454-20
7C451-30
7C453-30
7C454-30
Maximum Frequency (MHz)
83.3
71.4
50
33.3
Maximum Cascadable Frequency
83.3
71.4
50
33.3
Maximum Access Time (ns)
9
10
15
20
Minimum Cycle Time (ns)
12
14
20
30
Minimum Clock HIGH Time (ns)
5
6.5
9
12
Minimum Clock LOW Time (ns)
5
6.5
9
12
Minimum Data or Enable Set-Up (ns)
4
5
6
7
Minimum Data or Enable Hold (ns)
0
0
0
0
Maximum Flag Delay (ns)
9
10
15
20
Maximum Current (mA)
Commercial
140
140
120
100
Military/Industrial
150
150
130
110
Selection Guide (continued)
CY7C451
CY7C453
CY7C454
Density
512 x 9
2,048 x 9
4,096 x 9
OE, Depth Cascadable
Yes
Yes
Yes
Package
32-Pin PLCC
32-Pin PLCC
32-Pin PLCC
Operating Range
Range
Ambient
Temperature
VCC
Commercial
0
°C to +70°C
5V
± 10%
Industrial
−40
°C to +85°C
5V
± 10%
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