74AC244
OCTAL BUS BUFFER
WITH 3 STATE OUTPUTS (NON INVERTED)
s
s
s
s
s
s
s
s
s
HIGH SPEED: t
PD
= 3.8ns (TYP.) at V
CC
= 5V
LOW POWER DISSIPATION:
I
CC
= 4µA(MAX.) at T
A
=25°C
HIGH NOISE IMMUNITY:
V
NIH
= V
NIL
= 28 % V
CC
(MIN.)
50Ω TRANSMISSION LINE DRIVING
CAPABILITY
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 24mA (MIN)
BALANCED PROPAGATION DELAYS:
t
PLH
≅
t
PHL
OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 2V to 6V
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 244
IMPROVED LATCH-UP IMMUNITY
DIP
SOP
TSSOP
ORDER CODES
PACKAGE
DIP
SOP
TSSOP
TUBE
74AC244B
74AC244M
T&R
74AC244MTR
74AC244TTR
DESCRIPTION
The 74AC244 is an advanced high-speed CMOS
OCTAL BUS BUFFER (3-STATE) fabricated with
sub-micron silicon gate and double-layer metal
wiring C
2
MOS tecnology.
The G input controls four BUS BUFFERs.
This device is designed to be used with 3 state
memory address drivers, etc.
All inputs and outputs are equipped with
protection circuits against static discharge, giving
them 2KV ESD immunity and transient excess
voltage.
PIN CONNECTION AND IEC LOGIC SYMBOLS
April 2001
1/9
74AC244
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
1
2, 4, 6, 8
9, 7, 5, 3
11, 13, 15,
17
18, 16, 14,
12
19
10
20
SYMBOL
1G
1A1 to 1A4
2Y1 to 2Y4
2A1 to 2A4
1Y1 to 1Y4
2G
GND
V
CC
NAME AND FUNCTION
Output Enable Input
Data Inputs
Data Outputs
Data Inputs
Data Outputs
Output Enable Input
Ground (0V)
Positive Supply Voltage
TRUTH TABLE
INPUTS
G
L
L
H
X : Don’t Care
Z : High Impedance
OUTPUT
An
L
H
X
Yn
L
H
Z
ABSOLUTE MAXIMUM RATINGS
Symbol
V
CC
V
I
V
O
I
IK
I
OK
I
O
Supply Voltage
DC Input Voltage
DC Output Voltage
DC Input Diode Current
DC Output Diode Current
DC Output Current
Parameter
Value
-0.5 to +7
-0.5 to V
CC
+ 0.5
-0.5 to V
CC
+ 0.5
±
20
±
20
±
50
±
400
-65 to +150
300
Unit
V
V
V
mA
mA
mA
mA
°C
°C
I
CC
or I
GND
DC V
CC
or Ground Current
T
stg
Storage Temperature
T
L
Lead Temperature (10 sec)
Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is
not implied.
RECOMMENDED OPERATING CONDITIONS
Symbol
V
CC
V
I
V
O
T
op
dt/dv
Supply Voltage
Input Voltage
Output Voltage
Operating Temperqture
Input Rise and Fall Time V
CC
= 3.0, 4.5 or 5.5V (note 1)
Parameter
Value
2 to 6
0 to V
CC
0 to V
CC
-55 to 125
8
Unit
V
V
V
°C
ns/V
1) V
IN
from 30% to 70% of V
CC
2/9
74AC244
DC SPECIFICATIONS
Test Condition
Symbol
Parameter
V
CC
(V)
3.0
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
3.0
4.5
5.5
V
OL
Low Level Output
Voltage
3.0
4.5
5.5
3.0
4.5
5.5
I
I
Ioz
Input Leakage
Current
High Impedance
Output Leakage
Current
Quiescent Supply
Current
Dynamic Output
Current (note 1, 2)
5.5
5.5
5.5
5.5
V
O
= 0.1 V or
V
CC
-0.1V
V
O
= 0.1 V or
V
CC
-0.1V
I
O
=-50
µA
I
O
=-50
µA
I
O
=-50
µA
I
O
=-12 mA
I
O
=-24 mA
I
O
=-24 mA
I
O
=50
µA
I
O
=50
µA
I
O
=50
µA
I
O
=12 mA
I
O
=24 mA
I
O
=24 mA
V
I
= V
CC
or GND
V
I
= V
IH
or V
IL
V
O
= V
CC
or GND
V
I
= V
CC
or GND
V
OLD
= 1.65 V max
V
OHD
= 3.85 V min
2.9
4.4
5.4
2.56
3.86
4.86
0.002
0.001
0.001
0.1
0.1
0.1
0.36
0.36
0.36
±
0.1
±
0.5
4
T
A
= 25°C
Min.
2.1
3.15
3.85
Typ.
1.5
2.25
2.75
1.5
2.25
2.75
2.99
4.49
5.49
Max.
Value
-40 to 85°C
Min.
2.1
3.15
3.85
0.9
1.35
1.65
2.9
4.4
5.4
2.46
3.76
4.76
0.1
0.1
0.1
0.44
0.44
0.44
±
1
±
2.5
40
75
-75
0.9
1.35
1.65
2.9
4.4
5.4
2.4
3.7
4.7
0.1
0.1
0.1
0.5
0.5
0.5
±
1
±
5
80
50
-50
µA
µA
µA
mA
mA
V
V
Max.
-55 to 125°C
Min.
2.1
3.15
3.85
0.9
1.35
1.65
Max.
V
Unit
V
IH
High Level Input
Voltage
Low Level Input
Voltage
High Level Output
Voltage
V
IL
V
V
OH
I
CC
I
OLD
I
OHD
1) Maximum test duration 2ms, one output loaded at time
2) Incident wave switching is guaranteed on transmission lines with impedances as low as 50Ω
3/9
74AC244
AC ELECTRICAL CHARACTERISTICS
(C
L
= 50 pF, R
L
= 500
Ω,
Input t
r
= t
f
= 3ns)
Test Condition
Symbol
Parameter
V
CC
(V)
3.3
(*)
5.0
(**)
3.3
(*)
5.0
(**)
3.3
(*)
5.0
(**)
T
A
= 25°C
Min.
1.5
1.5
1.5
1.5
1.5
1.5
Typ.
5.2
3.8
6.1
4.2
6.8
5.4
Max.
9.0
7.0
10.5
8.0
10.5
9.0
Value
-40 to 85°C
Min.
1.5
1.5
1.5
1.5
1.5
1.5
Max.
10.0
7.5
11.0
8.5
11.5
9.5
-55 to 125°C
Min.
1.5
1.5
1.5
1.5
1.5
1.5
Max.
12.5
9.5
13.0
10.5
13.0
11.0
ns
ns
Unit
t
PLH
t
PHL
Propagation Delay
Time
t
PZL
t
PZH
Output Enable
Time
t
PLZ
t
PHZ
Output Disable
Time
(*) Voltage range is 3.3V
±
0.3V
(**) Voltage range is 5.0V
±
0.5V
ns
CAPACITIVE CHARACTERISTICS
Test Condition
Symbol
Parameter
V
CC
(V)
5.0
5.0
5.0
f
IN
= 10MHz
T
A
= 25°C
Min.
Typ.
4
8
21
Max.
Value
-40 to 85°C
Min.
Max.
-55 to 125°C
Min.
Max.
pF
pF
Unit
C
IN
C
OUT
C
PD
Input Capacitance
Output
Capacitance
Power Dissipation
Capacitance (note
1)
pF
1) C
PD
is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without
load. (Refer to Test Circuit). Average operating current can be obtained by the following equation. I
CC(opr)
= C
PD
x V
CC
x f
IN
+ I
CC
/8 (per circuit)
TEST CIRCUIT
TEST
t
PLH
, t
PHL
t
PZL
, t
PLZ
t
PZH
, t
PHZ
C
L
= 50pF or equivalent (includes jig and probe capacitance)
R
L
= R
1
= 500Ω or equivalent
R
T
= Z
OUT
of pulse generator (typically 50Ω)
SWITCH
Open
2V
CC
Open
4/9
74AC244
WAVEFORM 1: PROPAGATION DELAYS
(f=1MHz; 50% duty cycle)
WAVEFORM 2: OUTPUT ENABLE AND DISABLE TIME
(f=1MHz; 50% duty cycle)
5/9
嵌入式系统
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