74HCT4518 查看數據表（PDF） - Philips Electronics
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74HCT4518 Datasheet PDF : 7 Pages
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Philips Semiconductors
Dual synchronous BCD counter
Product specification
74HC/HCT4518
FEATURES
• Output capability: standard
• ICC category: MSI
GENERAL DESCRIPTION
The 74HC/HCT4518 are high-speed Si-gate CMOS
devices and are pin compatible with the “4518” of the
“4000B” series. They are specified in compliance with
JEDEC standard no. 7A.
The 74HC/HCT4518 are dual 4-bit internally synchronous
BCD counters with an active HIGH clock input (nCP0) and
an active LOW clock input (nCP1), buffered outputs from
all four bit positions (nQ0 to nQ3) and an active HIGH
overriding asynchronous master reset input (nMR).
The counter advances on either the LOW-to-HIGH
transition of nCP0 if nCP1 is HIGH or the HIGH-to-LOW
transition of nCP1 if nCP0 is LOW. Either nCP0 or nCP1
may be used as the clock input to the counter and the other
clock input may be used as a clock enable input. A HIGH
on nMR resets the counter (nQ0 to nQ3 = LOW)
independent of nCP0 and nCP1.
APPLICATIONS
• Multistage synchronous counting
• Multistage asynchronous counting
• Frequency dividers
QUICK REFERENCE DATA
GND = 0 V; Tamb = 25 °C; tr = tf = 6 ns
SYMBOL PARAMETER
CONDITIONS
TYPICAL
HC
HCT
tPHL/ tPLH propagation delay nCP0, nCP1 to nQn
CL = 15 pF; VCC = 5 V 20
24
tPHL
propagation delay nMR to nQn
13
14
fmax
maximum clock frequency
61
55
CI
input capacitance
3.5
3.5
CPD
power dissipation capacitance per counter notes 1 and 2
29
27
UNIT
ns
ns
MHz
pF
pF
Notes
1. CPD is used to determine the dynamic power dissipation (PD in µW):
PD = CPD × VCC2 × fi + ∑ (CL × VCC2 × fo) where:
fi = input frequency in MHz
fo = output frequency in MHz
∑ (CL × VCC2 × fo) = sum of outputs
CL = output load capacitance in pF
VCC = supply voltage in V
2. For HC the condition is VI = GND to VCC
For HCT the condition is VI = GND to VCC − 1.5 V
ORDERING INFORMATION
See “74HC/HCT/HCU/HCMOS Logic Package Information”.
December 1990
2
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