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PDF 74C926 Data sheet ( Hoja de datos )
| Número de pieza | 74C926 | |
| Descripción | 4-Digit Counters with Multiplexed | |
| Fabricantes | Fairchild Semiconductor | |
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October 1987
Revised January 1999
MM74C925 • MM74C926 • MM74C927 • MM74C928
4-Digit Counters with Multiplexed
7-Segment Output Drivers
General Description
The MM74C925, MM74C926, MM74C927 and MM74C928
CMOS counters consist of a 4-digit counter, an internal out-
put latch, NPN output sourcing drivers for a 7-segment dis-
play, and an internal multiplexing circuitry with four
multiplexing outputs. The multiplexing circuit has its own
free-running oscillator, and requires no external clock. The
counters advance on negative edge of clock. A HIGH sig-
nal on the Reset input will reset the counter to zero, and
reset the carry-out LOW. A LOW signal on the Latch
Enable input will latch the number in the counters into the
internal output latches. A HIGH signal on Display Select
input will select the number in the counter to be displayed;
a LOW level signal on the Display Select will select the
number in the output latch to be displayed.
The MM74C925 is a 4-decade counter and has Latch
Enable, Clock and Reset inputs.
The MM74C926 is like the MM74C925 except that it has a
display select and a carry-out used for cascading counters.
The carry-out signal goes HIGH at 6000, goes back LOW
at 0000.
The MM74C927 is like the MM74C926 except the second
most significant digit divides by 6 rather than 10. Thus, if
the clock input frequency is 10 Hz, the display would read
tenths of seconds and minutes (i.e., 9:59.9).
The MM74C928 is like the MM74C926 except the most sig-
nificant digit divides by 2 rather than 10 and the carry-out is
an overflow indicator which is HIGH at 2000, and it goes
back LOW only when the counter is reset. Thus, this is a
3½-digit counter.
Features
s Wide supply voltage range: 3V to 6V
s Guaranteed noise margin: 1V
s High noise immunity: 0.45 VCC (typ.)
s High segment sourcing current: 40 mA
@ VCC − 1.6V, VCC = 5V
s Internal multiplexing circuitry
Design Considerations
Segment resistors are desirable to minimize power dissipa-
tion and chip heating. The DS75492 serves as a good digit
driver when it is desired to drive bright displays. When
using this driver with a 5V supply at room temperature, the
display can be driven without segment resistors to full illu-
mination. The user must use caution in this mode however,
to prevent overheating of the device by using too high a
supply voltage or by operating at high ambient tempera-
tures.
The input protection circuitry consists of a series resistor,
and a diode to ground. Thus input signals exceeding VCC
will not be clamped. This input signal should not be allowed
to exceed 15V.
Ordering Code:
Order Number
MM74C925N
MM74C926N
MM74C927N
MM74C928N
Package Number
Package Description
N16E
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
N18A
18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
N18A
18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
N18A
18-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
© 1999 Fairchild Semiconductor Corporation DS005919.prf
www.fairchildsemi.com
1 page  
AC Electrical Characteristics (Note 3)
TA = 25°C, CL = 50 pF, unless otherwise noted
Symbol
Parameter
Conditions
fMAX
Maximum Clock Frequency
tr, tf Maximum Clock Rise or Fall Time
tWR Reset Pulse Width
tWLE
Latch Enable Pulse Width
tSET(CK, LE) Clock to Latch Enable Set-Up Time
tLR Latch Enable to Reset Wait Time
tSET(R, LE) Reset to Latch Enable Set-Up Time
fMUX
CIN
Multiplexing Output Frequency
Input Capacitance
VCC = 5V,
Tj = 25°C
Square Wave Clock Tj = 100°C
VCC = 5V
VCC = 5V
Tj = 25°C
Tj = 100°C
VCC = 5V
Tj = 25°C
Tj = 100°C
VCC = 5V
Tj = 25°C
Tj = 100°C
VCC = 5V
Tj = 25°C
Tj = 100°C
VCC = 5V
Tj = 25°C
Tj = 100°C
VCC = 5V
Any Input (Note 4)
Note 3: AC Parameters are guaranteed by DC correlated testing.
Note 4: Capacitance is guaranteed by periodic testing.
Typical Performance Characteristics
Min
2
1.5
250
320
250
320
2500
3200
0
0
320
400
1000
5
Typ
4
3
100
125
100
125
1250
1600
−100
−100
160
200
Max
15
Typical Segment Current
vs Output Voltage
Maximum Power Dissipation
vs Ambient Temperature
Units
MHz
MHz
µs
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Hz
pF
Note: VD = Voltage across digit driver
Typical Average Segment
Current vs Segment
Resistor Value
5 www.fairchildsemi.com
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| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet 74C926.PDF ] | |
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