HIT HD74HCT449 Datasheet
HD74HCT449
Quad. Bus Transceivers with Individual Direction Controls
Description
The HD74HCT449 has 4 bus transceivers. The device has direction control inputs with individual. And
this control inputs select data transmissible direction.
When GBA is high, A outputs are disable, and when GAB is high, B outputs are disable.
Features
• LSTTL Output Logic Level Compatibility as well as CMOS Output Compatibility
• High Speed Operation: tpd (A to B) = 12.5 ns typ (CL = 50 pF)
• High Output Current: Fanout of 15 LSTTL Loads
• Wide Operating Voltage: VCC = 4.5 to 5.5 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current: ICC (static) = 4 µA max (Ta = 25°C)
Function Table
Enable
GBA GAB Direction DIR Operation
H H X Isolation
X L H A data to B bus
L X L B data to A bus
X H H Isolation
H X L Isolation
H : High Level
L : Low Level
X : Irrelevant.
HD74HCT449
Pin Arrangement
GBA
A
1
2
1
16
15
V
CC
GAB
Logic Diagram
GBA
GAB
DIR
3
DIR2
4
A2
5
A3
6
DIR3
7
A4
8
GND
(Top view)
1
14
13
12
11
10
B
1
DIR1
B2
B3
DIR4
9
B4
A1 B1
To other three transceivers
2
HD74HCT449
Absolute Maximum Ratings
Item Symbol Rating Unit
Supply voltage range V
Input voltage V
Output voltage V
DC current drain per pin I
DC current drain per VCC, GND ICC, I
DC input diode current I
DC output diode current I
Power dissipation per package P
CC
IN
OUT
OUT
GND
IK
OK
T
Storage temperature Tstg –65 to +150 °C
DC Characteristics
Ta = –40 to
Ta = 25°C
Item Symbol Min Typ Max Min Max Unit V
Input voltage V
Output voltage V
IH
V
IL
OH
2.0 — — 2.0 — V 4.5 to
— — 0.8 — 0.8 V 4.5 to
4.4 — — 4.4 — V 4.5 Vin = VIH or VILIOH = –20 µA
4.18 — — 4.13 — 4.5 IOH = –6 mA
V
OL
— — 0.1 — 0.1 V 4.5 Vin = VIH or VILIOL = 20 µA
— — 0.26 — 0.33 4.5 IOL = 6 mA
Off-state output
I
OZ
——±0.5 — ±5.0 µA 5.5 Vin = VIH or VIL,
current
Input current Iin — — ±0.1 — ±1.0 µA 5.5 Vin = VCC or GND
Quiescent supply
I
CC
— — 4.0 — 40 µA 5.5 Vin = VCC or GND, Iout = 0 µA
current
+85°C Test Conditions
–0.5 to +7.0 V
–0.5 to VCC + 0.5 V
–0.5 to VCC + 0.5 V
±35 mA
±75 mA
±20 mA
±20 mA
500 mW
(V)
CC
5.5
5.5
Vout = V
or GND
CC
3
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