74ALS244 查看數據表（PDF） - Philips Electronics
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74ALS244 Datasheet PDF : 9 Pages
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Philips Semiconductors
Octal buffer (3-State)
Product specification
74ALS244A/74ALS244A-1
FEATURES
• Octal bus interface
• 3-State buffer outputs sink 24mA and source 15mA
• The -1 version sinks 48mA
DESCRIPTION
The 74ALS244A is an octal buffer that is ideal for driving bus lines or
buffer memory address registers. The outputs are all capable of
sinking 24mA and sourcing up to 15mA, producing very good
capacitive drive characteristics. The device features two output
enables, OEa and OEb, each controlling four of the 3-State outputs.
The 74ALS244A-1 sinks 48 mA IOL if the VCC is limited to
5.0V ±0.25V.
PIN CONFIGURATION
OEa 1
Ia0 2
Yb0 3
Ia1 4
Yb1 5
Ia2 6
Yb2 7
Ia3 8
Yb3 9
GND 10
20 VCC
19 OEb
18 Ya0
17 Ib0
16 Ya1
15 Ib1
14 Ya2
13 Ib2
12 Ya3
11 Ib3
SF00227
TYPE
74ALS244A
74ALS244A-1
TYPICAL
PROPAGATION
DELAY
4.5ns
4.5ns
TYPICAL
SUPPLY CURRENT
(TOTAL)
17mA
17mA
ORDERING INFORMATION
ORDER CODE
DESCRIPTION
COMMERCIAL RANGE
VCC = 5V ±10%,
Tamb = 0°C to +70°C
20-pin plastic DIP
74ALS244AN,
74ALS244A-1N
20-pin plastic SOL
74ALS244AD,
744ALS244A-1D
20-pin plastic
SSOP Type II
74ALS244ADB,
74ALS244A-1DB
DRAWING
NUMBER
SOT146-1
SOT163-1
SOT339-1
INPUT AND OUTPUT LOADING AND FAN-OUT TABLE
PINS
DESCRIPTION
74ALS (U.L.)
HIGH/LOW
Ian, Ibn
Data inputs
1.0/1.0
OEa, OEb
Output Enable inputs (active-Low)
1.0/1.0
Yan, Ybn
Data outputs
750/240
Yan, Ybn
Data outputs (-1 version)
750/480
NOTE: One (1.0) ALS unit load is defined as: 20µA in the High state and 0.1mA in the Low state.
LOAD VALUE
HIGH/LOW
20µA/0.1mA
20µA/0.1mA
15mA/24mA
15mA/48mA
LOGIC SYMBOL
IEC/IEEE SYMBOL
2 4 6 8 17 15 13 11
Ia0 Ia1 Ia2 Ia3 Ib0 Ib1 Ib2 Ib3
1
OEa
19
OEb
Ya0 Ya1 Ya2 Ya3 Yb0 Yb1 Yb2 Yb3
VCC = Pin 20
GND = Pin 10
18 16 14 12 3 5 7 9
SF00228
1
EN1
19
EN2
2
2D
1
4
6
8
17
2
15
13
11
18
16
14
12
3
5
7
9
SF00229
1991 Feb 08
2
853–1277 01670
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