Nexperia |
74HC238; 74HCT238 |
|
3-to-8 line decoder/demultiplexer |
10. Dynamic characteristics
Table 7. Dynamic characteristics
GND = 0 V; test circuit see Fig. 8.
Symbol |
|
Parameter |
Conditions |
|
|
25 °C |
|
-40 °C to |
-40 °C to |
Unit |
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+85 °C |
+125 °C |
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Min |
Typ |
Max |
Min |
Max |
Min |
Max |
|
74HC238 |
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tpd |
|
propagation |
An to Yn; see Fig. 6 |
[1] |
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delay |
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VCC = 2.0 V |
|
- |
47 |
150 |
- |
190 |
- |
225 |
ns |
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VCC = 4.5 V |
|
- |
17 |
30 |
- |
38 |
- |
45 |
ns |
|
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VCC = 5.0 V; CL = 15 pF |
|
- |
14 |
- |
- |
- |
- |
- |
ns |
|
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|
|
|
VCC = 6.0 V |
|
- |
14 |
26 |
- |
33 |
- |
38 |
ns |
|
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|
E3 to Yn; see Fig. 6 |
[1] |
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VCC = 2.0 V |
|
- |
52 |
160 |
- |
200 |
- |
240 |
ns |
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VCC = 4.5 V |
|
- |
19 |
32 |
- |
40 |
- |
48 |
ns |
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VCC = 5.0 V; CL = 15 pF |
|
- |
16 |
- |
- |
- |
- |
- |
ns |
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VCC = 6.0 V |
|
- |
15 |
27 |
- |
34 |
- |
41 |
ns |
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[1] |
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En to Yn or see Fig. 7 |
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VCC = 2.0 V |
|
- |
50 |
155 |
- |
195 |
- |
235 |
ns |
|
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|
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VCC = 4.5 V |
|
- |
18 |
31 |
- |
39 |
- |
47 |
ns |
|
|
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|
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VCC = 5.0 V; CL = 15 pF |
|
- |
17 |
- |
- |
- |
- |
- |
ns |
|
|
|
|
|
VCC = 6.0 V |
|
- |
14 |
26 |
- |
33 |
- |
40 |
ns |
tt |
|
transition time |
see Fig. 6 and Fig. 7 |
[2] |
|
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VCC = 2.0 V |
|
- |
19 |
75 |
- |
95 |
- |
110 |
ns |
|
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|
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VCC = 4.5 V |
|
- |
7 |
15 |
- |
19 |
- |
22 |
ns |
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VCC = 6.0 V |
|
- |
6 |
13 |
- |
16 |
- |
19 |
ns |
CPD |
|
power |
per package; VI = GND to VCC |
[3] |
- |
72 |
- |
- |
- |
- |
- |
pF |
||
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dissipation |
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capacitance |
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|
74HC_HCT238 |
All information provided in this document is subject to legal disclaimers. |
© Nexperia B.V. 2021. All rights reserved |
Product data sheet |
Rev. 7 — 2 September 2021 |
7 / 15 |
Nexperia |
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74HC238; 74HCT238 |
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3-to-8 line decoder/demultiplexer |
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Symbol |
|
Parameter |
Conditions |
|
|
25 °C |
|
-40 °C to |
-40 °C to |
Unit |
||||
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+85 °C |
+125 °C |
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Min |
Typ |
Max |
Min |
Max |
Min |
Max |
|
74HCT238 |
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tpd |
propagation |
An to Yn; see Fig. 6 |
[1] |
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delay |
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VCC = 4.5 V |
|
- |
19 |
35 |
- |
44 |
- |
53 |
ns |
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|||||||||
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VCC = 5.0 V; CL = 15 pF |
|
- |
18 |
- |
- |
- |
- |
- |
ns |
|
|
|
E3 to Yn; see Fig. 6 |
[1] |
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VCC = 4.5 V |
|
- |
20 |
37 |
- |
46 |
- |
56 |
ns |
|
|
|
|
|
VCC = 5.0 V; CL = 15 pF |
|
- |
20 |
- |
- |
- |
- |
- |
ns |
|
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[1] |
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En to Yn or see Fig. 7 |
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VCC = 4.5 V |
|
- |
20 |
35 |
- |
44 |
- |
53 |
ns |
|
|
|
|
|
VCC = 5.0 V; CL = 15 pF |
|
- |
21 |
- |
- |
- |
- |
- |
ns |
tt |
transition time |
VCC = 4.5 V; |
[2] |
- |
7 |
15 |
- |
19 |
- |
22 |
ns |
|||
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|
|
see Fig. 6 and Fig. 7 |
|
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CPD |
power |
per package; |
[3] |
- |
76 |
- |
- |
- |
- |
- |
pF |
|||
|
|
dissipation |
VI = GND to VCC - 1.5 V |
|
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|
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capacitance |
|
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|
[1]tpd is the same as tPHL and tPLH.
[2]tt is the same as tTHL and tTLH.
[3]CPD is used to determine the dynamic power dissipation (PD in μW): PD = CPD x VCC 2 x fi x N + ∑ (CL x VCC 2 x fo) where:
fi = input frequency in MHz; fo = output frequency in MHz;
CL = output load capacitance in pF; VCC = supply voltage in V;
N = number of inputs switching;
∑(CL x VCC 2 x fo) = sum of outputs.
10.1.Waveforms and test circuit
An, E3 input |
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VM |
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tPHL |
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tPLH |
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Yn output |
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VY |
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VM |
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VX |
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tTHL |
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tTLH |
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001aag757 |
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Measurement points are given in Table 8.
Fig. 6. Input (An, E3) to output (Yn) propagation delays and output transition times
74HC_HCT238 |
All information provided in this document is subject to legal disclaimers. |
© Nexperia B.V. 2021. All rights reserved |
Product data sheet |
Rev. 7 — 2 September 2021 |
8 / 15 |
Nexperia |
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74HC238; 74HCT238 |
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3-to-8 line decoder/demultiplexer |
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VM |
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E1, E2 input |
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tPHL |
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tPLH |
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VY |
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VM |
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Yn output |
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VX |
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tTHL |
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tTLH |
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001aag758 |
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Measurement points are given in Table 8.
Fig. 7. Input (E1, E2) to output (Yn) propagation delays and output transition times
Table 8. Measurement points
Type |
Input |
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Output |
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VM |
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VM |
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VX |
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VY |
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74HC238 |
0.5VCC |
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0.5VCC |
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0.1VCC |
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0.9VCC |
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74HCT238 |
1.3 V |
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1.3 V |
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0.1VCC |
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0.9VCC |
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VI |
90 % |
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tW |
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negative |
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VM |
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VM |
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pulse |
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0 V |
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10 % |
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tf |
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pulse |
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tW |
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VCC |
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VCC |
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VI |
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DUT |
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L |
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RT |
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CL |
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001aad983 |
|||
Test data is given in Table 9. Definitions for 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
Fig. 8. Test circuit for measuring switching times
Table 9. Test data
Type |
Input |
|
Load |
|
S1 position |
|
VI |
tr, tf |
CL |
RL |
tPHL, tPLH |
74HC238 |
VCC |
6 ns |
15 pF, 50 pF |
1 kΩ |
open |
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74HCT238 |
3 V |
6 ns |
15 pF, 50 pF |
1 kΩ |
open |
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74HC_HCT238 |
All information provided in this document is subject to legal disclaimers. |
© Nexperia B.V. 2021. All rights reserved |
Product data sheet |
Rev. 7 — 2 September 2021 |
9 / 15 |