These CMOS key encoders provide all the necessary logic
to fully encode an array of SPST switches The keyboard
scan can be implemented by either an external clock or
external capacitor These encoders also have on-chip pull-
up devices which permit switches with up to 50 kX on resist-
ance to be used No diodes in the switch array are needed
to eliminate ghost switches The internal debounce circuit
needs only a single external capacitor and can be defeated
by omitting the capacitor A Data Available output goes to a
high level when a valid keyboard entry has been made The
Data Available output returns to a low level when the en-
tered key is released even if another key is depressed The
Data Available will return high to indicate acceptance of the
new key after a normal debounce period this two-key roll-
over is provided between any two switches
An internal register remembers the last key pressed even
after the key is released The TRI-STATE outputs provide
for easy expansion and bus operation and are LPTTL com-
patible
Features
Y
Y
Y
Y
Y
Y
Y
Y
Y
Connection Diagrams
Pin Assignment for
Dual-In-Line Package
Pin Assignment
for SOIC
bs
ol
TL F 6037 – 14
TL F 6037–1
Order Number MM74C922
Top View
Order Number MM54C922 or
MM74C922
O
TRI-STATE is a registered trademark of National Semiconductor Corporation
C
1995 National Semiconductor Corporation
TL F 6037
et
Pin Assignment for
DIP and SOIC Package
Top View
TL F 6037 – 2
50 kX maximum switch on resistance
On or off chip clock
On-chip row pull-up devices
2 key roll-over
Keybounce elimination with single capacitor
Last key register at outputs
TRI-STATE outpust LPTTL compatible
Wide supply range
Low power consumption
e
3V to 15V
Top View
Order Number MM54C923 or
MM74C923
RRD-B30M105 Printed in U S A
Absolute Maximum Ratings
(Note 1)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Voltage at Any Pin
V
CC
b
0 3V to V
CC
a
0 3V
Operating Temperature Range
MM54C922 MM54C923
MM74C922 MM74C923
b
55 C to
a
125 C
b
40 C to
a
85 C
Storage Temperature Range
Power Dissipation (P
D
)
Dual-In-Line
Small Outline
Operating V
CC
Range
V
CC
Lead Temperature
(Soldering 10 seconds)
b
65 C to
a
150 C
700 mW
500 mW
3V to 15V
18V
260 C
DC Electrical Characteristics
Min
Symbol
CMOS TO CMOS
V
T
a
Positive-Going Threshold Voltage
at Osc and KBM Inputs
Negative-Going Threshold Voltage
at Osc and KBM Inputs
Logical ‘‘1’’ Input Voltage
Except Osc and KBM Inputs
Logical ‘‘0’’ Input Voltage
Except Osc and KBM Inputs
Row Pull-Up Current at Y1 Y2
Y3 Y4 and Y5 Inputs
Logical ‘‘1’’ Output Voltage
Parameter
Max limits apply across temperature range unless otherwise specified
Conditions
Min
30
60
90
07
14
21
35
80
12 5
Typ
36
68
10
14
32
5
45
9
13 5
05
1
15
Max
43
86
12 9
20
40
60
Units
V
V
V
V
V
V
V
V
V
V
V
V
V
CC
e
5V I
IN
t
0 7 mA
V
CC
e
10V I
IN
t
1 4 mA
V
CC
e
15V I
IN
t
2 1 mA
V
CC
e
5V I
IN
t
0 7 mA
V
CC
e
10V I
IN
t
1 4 mA
V
CC
e
15V I
IN
t
2 1 mA
V
CC
e
5V
V
CC
e
10V
V
CC
e
15V
V
CC
e
5V
V
CC
e
10V
V
CC
e
15V
V
T
b
V
IN(1)
V
IN(0)
I
rp
V
CC
e
5V V
IN
e
0 1 V
CC
V
CC
e
10V
V
CC
e
15V
V
OUT(1)
V
OUT(0)
Logical ‘‘0’’ Output Voltage
bs
ol
V
CC
e
5V I
O
e
10
mA
V
CC
e
10V I
O
e
10
mA
V
CC
e
15V I
O
e
10
mA
V
CC
e
5V V
O
e
0 5V
V
CC
e
10V V
O
e
1V
V
CC
e
15V V
O
e
1 5V
V
CC
e
5V
V
CC
e
10V
V
CC
e
15V
V
CC
e
15V V
IN
e
15V
V
CC
e
15V V
IN
e
0V
b
1 0
V
CC
e
5V I
O
e b
10
mA
V
CC
e
10V I
O
e b
10
mA
V
CC
e
15V I
O
e b
10
mA
et
b
2
b
10
b
22
b
5
b
20
b
45
R
on
Column ‘‘ON’’ Resistance at
X1 X2 X3 and X4 Outputs
Supply Current
Osc at 0V (one Y low)
I
CC
I
IN(1)
I
IN(0)
Logical ‘‘1’’ Input Current
at Output Enable
Logical ‘‘0’’ Input Current
at Output Enable
CMOS LPTTL INTERFACE
V
IN(1)
V
IN(0)
O
Logical ‘‘1’’ Input Voltage
Except Osc and KBM Inputs
Logical ‘‘0’’ Input Voltage
Except Osc and KBM Inputs
Logical ‘‘1’’ Output Voltage
V
OUT(1)
V
OUT(0)
Logical ‘‘0’’ Output Voltage
54C V
CC
e
4 5V
74C V
CC
e
4 75V
54C V
CC
e
4 5V
74C V
CC
e
4 75V
54C V
CC
e
4 5V
I
O
e b
360
mA
74C V
CC
e
4 75V
I
O
e b
360
mA
54C V
CC
e
4 5V
I
O
e b
360
mA
74C V
CC
e
4 75V
I
O
e b
360
mA
Note 1
‘‘Absolute Maximum Ratings’’ are those values beyond which the safety of the device cannot be guaranteed Except for ‘‘Operating Temperature Range’’
they are not meant to imply that the devices should be operated at these limits The table of ‘‘Electrical Characteristics’’ provides conditions for actual device
operation
2
e
15
2
25
mA
mA
mA
V
V
V
V
V
V
X
X
X
mA
mA
mA
mA
mA
45
9
13 5
05
1
15
1400
700
500
11
19
26
10
500
300
200
0 55
11
17
0 005
b
0 005
V
CC
b
1 5
V
CC
b
1 5
08
08
24
24
04
04
V
V
V
V
V
V
V
V
DC Electrical Characteristics
Min Max limits apply across temperature range unless otherwise specified (Continued)
Symbol
I
SOURCE
I
SOURCE
I
SINK
I
SINK
Parameter
Output Source Current
(P-Channel)
Output Source Current
(P-Channel)
Output Sink Current
(N-Channel)
Output Sink Current
(N-Channel)
Conditions
V
CC
e
5V V
OUT
e
0V
T
A
e
25 C
V
CC
e
10V V
OUT
e
0V
T
A
e
25 C
V
CC
e
5V V
OUT
e
V
CC
T
A
e
25 C
V
CC
e
10V V
OUT
e
V
CC
T
A
e
25 C
Min
Typ
Max
Units
OUTPUT DRIVE (See 54C 74C Family Characteristics Data Sheet) (Short Circuit Current)
b
1 75
b
8
b
3 3
b
15
mA
mA
mA
mA
1 75
8
36
16
AC Electrical Characteristics
Symbol
t
pd0
t
pd1
Parameter
Propagation Delay Time to
Logical ‘‘0’’ or Logical ‘‘1’’
from D A
Propagation Delay Time from
Logical ‘‘0’’ or Logical ‘‘1’’
into High Impedance State
Propagation Delay Time from
High Impedance State to a
Logical ‘‘0’’ or Logical ‘‘1’’
Input Capacitance
TRI-STATE Output Capacitance
T
A
e
25 C C
L
e
50 pF unless otherwise noted
Conditions
C
L
e
50 pF
(Figure 1)
V
CC
e
5V
V
CC
e
10V
V
CC
e
15V
Min
Typ
60
35
25
Max
150
80
60
Units
ns
ns
ns
ns
ns
ns
ns
ns
ns
pF
pF
t
0H
t
1H
t
H0
t
H1
R
L
e
10k C
L
e
50 pF
(Figure 2)
V
CC
e
5V R
L
e
10k
V
CC
e
10V C
L
e
50 pF
V
CC
e
15V
Any Input (Note 2)
Any Output (Note 2)
C
IN
C
OUT
AC Parameters are guaranteed by DC correlated testing
Note 1
‘‘Absolute Maximum Ratings’’ are those values beyond which the safety of the device cannot be guaranteed Except for ‘‘Operating Temperature Range’’
they are not meant to imply that the devices should be operated at these limits The table of ‘‘Electrical Characteristics’’ provides conditions for actual device
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