74F794 8-Bit Register with Readback
March 1990
Revised August 1999
74F794
8-Bit Register with Readback
General Description
The 74F794 is an 8-bit register with readback capability
designed to store data as well as read the register informa-
tion back onto the data bus. The I/O bus (D bus) has 3-
STATE outputs. Current sinking capability is 64 mA on both
the D and Q busses.
Data is loaded into the registers on the LOW-to-HIGH tran-
sition of the clock (CP). The output enable (OE) is used to
enable data on D
0
–D
7
. When OE is LOW, the output of the
registers is enabled on D
0
–D
7
, enabling D as an output
bus. When OE is HIGH, D
0
–D
7
are inputs to the registers
configuring D as an input bus.
Features
s
3-STATE outputs on the I/O port
s
D and Q output sink capability of 64 mA
s
Functionally and pin equivalent to the 74LS794
Ordering Code:
Order Number
74F794SC
74F794PC
Package Number
M20B
N20A
Package Description
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Logic Symbol
Connection Diagram
© 1999 Fairchild Semiconductor Corporation
DS010652
www.fairchildsemi.com
74F794
Absolute Maximum Ratings
(Note 2)
Storage Temperature
Ambient Temperature under Bias
Junction Temperature under Bias
V
CC
Pin Potential to Ground Pin
Input Voltage (Note 3)
Input Current (Note 3)
ESD Last Passing Voltage (Min)
Voltage Applied to Output
In HIGH State (with V
CC
=
0V)
Standard Output
3-STATE Output
Current Applied to Output
in LOW State (Max)
Twice the Rated I
OL
(mA)
−0.5V
to V
CC
−0.5V
to
+5.5V
−65°C
to
+
150°C
−55°
to
+125°C
−55°C
to
+150°C
−0.5V
to
+7.0V
−0.5V
to
+7.0V
−30
mA to
+5.0
mA
4000V
Recommended Operating
Conditions
Free Air Ambient Temperature
Supply Voltage
0°C to 70°C
+4.5V
to
+5.5V
Note 2:
Absolute maximum ratings are values beyond which the device
may be damaged or have its useful life impaired. Functional operation
under these conditions is not implied.
Note 3:
In this case the output of the register is clocked to the inputs and
the overall Q output is unchanged at Q
n
.
Note 4:
Either voltage limit or current limit is sufficient to protect inputs.
DC Electrical Characteristics
Symbol
V
IH
V
IL
V
CD
V
OH
V
OL
I
IH
I
BVI
I
BVIT
I
CEX
V
ID
I
OD
I
IL
I
OS
I
IH
+
I
OZH
I
IL
+
I
OZL
V
ID
I
OD
I
ZZ
I
CCH
I
CCL
I
CCZ
Output Leakage
Current
Input Leakage
Test
Output Circuit
Leakage Current
Bus Drainage Test
Power Supply Current
Power Supply Current
Power Supply Current
4.75
Parameter
Input HIGH Voltage
Input LOW Voltage
Input Clamp
Diode Voltage
Output HIGH
Voltage
Output LOW
Voltage
Input HIGH
Current
Input HIGH Current
Breakdown Test
Input HIGH Current
Breakdown (I/O)
Output HIGH
Leakage Current
Input Leakage
Test
Output Leakage
Circuit Current
Input LOW
Current
Output Short-
Circuit Current
Output Leakage Current
4.75
2.4
2.0
Min
2.0
over Operating Temperature Range unless otherwise specified
Typ
Max
Units
V
0.8
−1.2
2.8
2.44
0.45
0.55
5.0
V
V
V
V
µA
µA
mA
µA
V
3.75
−0.6
µA
mA
mA
µA
µA
V
3.75
100
65
80
80
µA
µA
mA
mA
mA
Min
Min
Min
Max
V
CC
Conditions
Recognized as a HIGH Signal
Recognized as a LOW Signal
I
IN
= −18
mA
I
OH
= −3
mA
I
OH
= −15
mA
I
OL
=
64 mA
V
IN
=
2.7V
V
IN
=
7.0V (OE, CP)
V
IN
=
5.5V (D
n
)
V
OUT
=
V
CC
I
ID
=
1.9
µA
All Other Pins Grounded
V
IOD
=
150 mV
All Other Pins Grounded
V
IN
=
0.5V
(OE, CP)
V
OUT
=
0V
V
OUT
=
2.7V
(Dn)
V
OUT
=
0.5V
(Dn)
I
ID
=
1.9
µA
All Other Pins Grounded
V
IOD
=
150 mV
All Other Pins Grounded
V
OUT
=
5.25V
V
O
=
HIGH
V
O
=
LOW
V
O
=
HIGH Z
7.0
0.5
50
Max
Max
Max
0.0
0.0
Max
Max
Max
Max
0.0
0.0
0.0
Max
Max
Max
−100
−225
70
−650
3
www.fairchildsemi.com
74F794
Physical Dimensions
inches (millimeters) unless otherwise noted
20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
Package Number M20B
5
www.fairchildsemi.com
Microcontroller MCU
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