HD74HC251 查看數據表（PDF） - Renesas Electronics
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HD74HC251 Datasheet PDF : 9 Pages
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HD74HC251
Switching Characteristics
Item
Symbol VCC (V)
Propagation delay tPLH
2.0
time
tPHL
4.5
6.0
tPLH
2.0
tPHL
4.5
6.0
tPLH
2.0
tPHL
4.5
6.0
tPLH
2.0
tPHL
4.5
6.0
Output enable time tZH
2.0
tZL
4.5
6.0
tZH
2.0
tZL
4.5
6.0
Output disable
time
tHZ
2.0
tLZ
4.5
6.0
tHZ
2.0
tLZ
4.5
6.0
Output rise/fall
time
tTLH
2.0
tTHL
4.5
6.0
Input capacitance Cin
—
Ta = 25°C
Min Typ Max
— — 205
— 20 41
— — 35
— — 205
— 20 41
— — 35
— — 195
— 17 39
— — 33
— — 185
— 17 37
— — 31
— — 150
— 11 30
— — 26
— — 145
— 11 29
— — 25
— — 220
— 12 44
— — 37
— — 195
— 12 39
— — 33
— — 75
— 5 15
— — 13
— 5 10
(CL = 50 pF, Input tr = tf = 6 ns)
Ta = –40 to +85°C
Unit
Min
Max
Test Conditions
—
255 ns A, B or C to Y
—
51
—
43
—
255 ns A, B or C to W
—
51
—
43
—
245 ns Data to Y
—
49
—
42
—
230 ns Data to W
—
46
—
39
—
190 ns strobe to W RL = 1 kΩ
—
38
—
33
—
180 ns strobe to Y RL = 1 kΩ
—
36
—
31
—
275 ns strobe to W RL = 1 kΩ
—
55
—
47
—
245 ns strobe to Y RL = 1 kΩ
—
49
—
42
—
90
ns
—
19
—
16
—
10 pF
Test Circuit
VCC
Input
Pulse Generator
Zout = 50 Ω
VCC
Output
S
Y
D0 to D7
A
B
C
Output
W
1 k Ω S1
CL =
50 pF
1 k Ω S1
CL =
50 pF
Note : 1. CL includes probe and jig capacitance.
OPEN
GND
VCC
OPEN
GND
VCC
TEST
tPLH / t PHL
tZH/ t HZ
tZL / t LZ
S1
OPEN
GND
VCC
Rev.2.00 Jan 31, 2006 page 5 of 8
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