74HC138BQ 데이터 시트보기 (PDF) - Nexperia B.V. All rights reserved
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74HC138BQ Datasheet PDF : 16 Pages
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Nexperia
74HC138; 74HCT138
3-to-8 line decoder/demultiplexer; inverting
Fig. 8.
VCC
E1, E2
input
GND
VOH
VM
tPHL
tPLH
Yn
output
VOL
VM
tTHL
tTLH
mna374
Measurement points are given in Table 8.
VOL and VOH are typical voltage output levels that occur with the output load.
Propagation delay enable input (En) to output (Yn) and transition time output (Yn)
Table 8. Measurement points
Type
74HC138
74HCT138
Input
VM
0.5VCC
1.3 V
Output
VM
0.5VCC
1.3 V
VI 90 %
tW
negative
pulse
VM
10 %
0V
tf
VI
positive
pulse
tr
90 %
VM
10 %
0V
tW
VM
tr
tf
VM
VI
G
VCC
VO
DUT
RT
VCC
RL S1
CL
open
Fig. 9.
001aad983
Test data is given in Table 9.
Definitions test circuit:
RT = Termination resistance should be equal to output impedance Zo of the pulse generator.
CL = Load capacitance including jig and probe capacitance.
RL = Load resistance.
S1 = Test selection switch.
Test circuit for measuring switching times
Table 9. Test data
Type
Input
74HC138
VI
tr, tf
VCC
6 ns
74HCT138
3V
6 ns
Load
CL
15 pF, 50 pF
15 pF, 50 pF
RL
1 kΩ
1 kΩ
S1 position
tPHL, tPLH
open
tPZH, tPHZ
GND
open
GND
tPZL, tPLZ
VCC
VCC
74HC_HCT138
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 8 — 7 April 2020
© Nexperia B.V. 2020. All rights reserved
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