Timeline for Why do two different ICs have wildly different high level output voltages?
Current License: CC BY-SA 3.0
17 events
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| Feb 22, 2018 at 22:28 | comment | added | TonyM | @Bimpelrekkie, you can expect very small differences between 74LS ICs. But by nowhere near that much. Logic ICs are very consistent across devices. And yes, LS outputs do produce much higher output voltages than 3.3V, your interpretation of the data sheet is wrong. I built and worked on plenty of LS designs in the past. The OP's odd voltages are definitely unusual. | |
| Feb 21, 2018 at 10:51 | history | edited | Michael Karas | CC BY-SA 3.0 |
Corrected spellings and typos.
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| Feb 21, 2018 at 10:46 | history | edited | Curd | CC BY-SA 3.0 |
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| Feb 21, 2018 at 10:39 | history | edited | Curd | CC BY-SA 3.0 |
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| Feb 21, 2018 at 10:35 | vote | accept | DylanG | ||
| Feb 21, 2018 at 10:35 | comment | added | Curd | @DylanG: then see the others reasons I've listed! | |
| Feb 21, 2018 at 10:32 | history | edited | Curd | CC BY-SA 3.0 |
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| Feb 21, 2018 at 10:32 | comment | added | DylanG | @Curd yes they are indeed both LS | |
| Feb 21, 2018 at 10:28 | history | edited | Curd | CC BY-SA 3.0 |
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| Feb 21, 2018 at 10:22 | history | edited | Curd | CC BY-SA 3.0 |
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| Feb 21, 2018 at 10:20 | comment | added | Curd | @Bimpelrekkie: OP claimed they are both are LS; so I trusted that this is really the case. | |
| Feb 21, 2018 at 10:16 | comment | added | Curd | @Dylan: Why do you assume they should be exactly the same? There are plenty reasons not to be the same. See my edit. | |
| Feb 21, 2018 at 10:15 | history | edited | Curd | CC BY-SA 3.0 |
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| Feb 21, 2018 at 10:14 | comment | added | Bimpelrekkie | I am just wondering why I might be seeing such a difference in output voltage That will be caused by differences between circuits in the IC. When I look at the 74LS04's schematics (TI datasheet) then I do not see how the output could reach 4.5 V. Are you sure it is a "LS04" and not something else like HC04. Looking at the schematics both LS chips should output around 3.3 V and not 4.5 V. | |
| Feb 21, 2018 at 10:08 | history | edited | Curd | CC BY-SA 3.0 |
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| Feb 21, 2018 at 10:05 | comment | added | DylanG | The output voltages are well within spec I am not worried about that. I am just wondering why I might be seeing such a difference in output voltage when the ICs are both from the same logic family and are both being powered with a single 5V supply | |
| Feb 21, 2018 at 10:02 | history | answered | Curd | CC BY-SA 3.0 |