Philips Semiconductors
Product specification
16
×
5 asynchronous FIFO (3-State)
74F225
FEATURES
•
Independent synchronous inputs and outputs
•
Organized as 16 words of 5 bits
•
DC to 25MHz data rate
•
3–State outputs
•
Cascadable in word–width and depth direction
DESCRIPTION
This 80–bit active element First–In–First–Out (FIFO) is a monolithic
Schottky–clamped transistor–transistor logic (STTL) array organized
as 16–words of 5–bits each. A memory system using the ’F225 can
be easily expanded in multiples of 16–words of 5–bits as shown in
Figure 1. The 3–State outputs controlled by a single enable input
(OE) make bus connection and multiplexing simple. The ’F225
processes data in a parallel format at any desired clock rate from
DC to 25MHz. Status of the ’F225 is provided by three outputs, Input
Ready (IR), Unload Clock Output (UNCPOUT) and Output Ready
(OR). The data outputs are non–inverting with respect to the data
inputs and are disabled when the OE input is High. When OE is
Low, the data outputs are enabled to function as totem–pole outputs.
TYPICAL SUPPLY
CURRENT
( TOTAL)
65mA
TYPE
74F225
TYPICAL f
MAX
25MHz
ORDERING INFORMATION
ORDER CODE
DESCRIPTION
COMMERCIAL RANGE
V
CC
= 5V
±
10%,
T
amb
= 0
°
C to +70
°
C
N74F225N
N74F225D
PKG DWG #
20–pin plastic DIP
20–pin plastic SOL
SOT146-1
SOT163-1
INPUT AND OUTPUT LOADING AND FAN OUT TABLE
PINS
CPA, CPB
D0 – D4
OE
UNCPIN
MR
IR
UNCPOUT
Q0 – Q4
DESCRIPTION
Load clock A and load clock B inputs
Data inputs
Output enable input (active–Low)
Unload clock input
Master reset input (active–Low)
Input ready output
Unload clock output (active–Low)
Data outputs
74F (U.L.)
HIGH/LOW
1.0/0.033
1.0/0.033
1.0/0.033
1.0/0.033
1.0/0.033
50/33
50/33
150/40
50/33
LOAD VALUE
HIGH/LOW
20µA/20µA
20µA/20µA
20µA/20µA
20µA/20µA
20µA/20µA
1.0mA/20mA
1.0mA/20mA
3.0mA/24mA
1.0mA/20mA
OR
Output ready output
NOTE:
One (1.0) FAST unit load is defined as: 20µA in the High state and 0.6mA in the Low state.
RESET MODE
A High–to–Low transition on the Master Reset (MR) input invalidates
all data stored in the FIFO by clearing the control logic and setting
OR Low. This High–to–Low transition on the MR input does not
effect the data outputs but since OR is driven Low, it signifies invalid
data on the outputs.
READ MODE
The Output Ready (OR) output is High when valid data is present on
the data outputs. Data in the array is shifted on the Low–to–High
transition of the Unload Clock Input (UNCPIN). In order for Output
Ready (OR) to go High, Unload Clock Input (UNCPIN) must also be
High.
WRITE MODE
Data may be written into the array on the Low–to–High transition of
either load clock (CPA or CPB) input. When writing data into the
FIFO, one of the load clock inputs must be held High while the other
strobes data into the FIFO. This arrangement allows either load
clock to function as an inhibit for the other. Input Ready (IR)
monitors the status of the last word location and signifies when the
FIFO is full. This output is High whenever the FIFO is available to
accept new data. The unload clock output (UNCPOUT) also
monitors the last word location. This output generates a
Low–logic–level pulse (synchronized to the internal clock pulse)
when the last word location is vacant
June 15, 1992
2
853-1652 06992
Philips Semiconductors
Product specification
16
×
5 asynchronous FIFO (3-State)
74F225
ABSOLUTE MAXIMUM RATINGS
(Operation beyond the limit set forth in this table may impair the useful life of the device. Unless otherwise noted these limits are over the
operating free air temperature range.)
SYMBOL
V
CC
V
IN
I
IN
V
OUT
I
OUT
Supply voltage
Input voltage
Input current
Voltage applied to output in High output state
Current applied to output in Low output state
Current applied to output in Low output state
T
amb
T
stg
Operating free air temperature range
Storage temperature range
IR, OR, UNCPOUT
Data outputs
PARAMETER
RATING
–0.5 to +7.0
–0.5 to +7.0
–30 to +5
–0.5 to V
CC
40
48
0 to +70
–65 to +150
UNIT
V
V
mA
V
mA
mA
°
C
°
C
RECOMMENDED OPERATING CONDITIONS
SYMBOL
V
CC
V
IN
V
IL
I
Ik
I
OH
I
OL
T
amb
Supply voltage
High–level input voltage
Low–level input voltage
Input clamp current
High–level output current
Low–level output current
IR, OR, UNCPOUT
Data outputs
IR, OR, UNCPOUT
Data outputs
Operating free air temperature range
0
PARAMETER
MIN
4.5
2.0
0.8
–18
–1
–3
20
24
+70
LIMITS
NOM
5.0
MAX
5.5
V
V
V
mA
mA
mA
mA
mA
UNIT
°
C
June 15, 1992
5
嵌入式系统
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