Timeline for How to switch "best" between two voltage sources (5V & 3V3) for a single output ("MUX for VCC")?
Current License: CC BY-SA 4.0
21 events
| when toggle format | what | by | license | comment | |
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| Apr 7, 2021 at 20:11 | history | edited | mythbu | CC BY-SA 4.0 |
fixed image mixup
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| Apr 7, 2021 at 8:54 | vote | accept | mythbu | ||
| Apr 7, 2021 at 8:54 | vote | accept | mythbu | ||
| Apr 7, 2021 at 8:54 | |||||
| Apr 7, 2021 at 8:53 | history | edited | mythbu | CC BY-SA 4.0 |
added a solution schematic proposed by a user
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| Apr 6, 2021 at 15:34 | answer | added | D.A.S. | timeline score: 1 | |
| Apr 6, 2021 at 15:20 | comment | added | Justme | @mythbu Why can't there be both 5V supply and 3.3V supply pins and the module that gets plugged in uses the right supply pin? This way the user cannot select 5V output while the 3.3V module is connected so there is no damage. Which sensors those are, are they analog or have some bus like I2C? | |
| Apr 6, 2021 at 14:22 | answer | added | AnalogKid | timeline score: 2 | |
| Apr 6, 2021 at 14:11 | comment | added | mythbu | @SteveSh Thanks! One potential problem could be the contact bounce for the sensors. Maybe a smoothing cap could help here. | |
| Apr 6, 2021 at 14:10 | comment | added | mythbu | @Hearth: if I go with this design I'll optimize it for sure. Makes no much sense to waste this; it was just the first one I got on Mouser, therefore I took it for this example - so no deeper sense | |
| Apr 6, 2021 at 14:08 | comment | added | mythbu | @Justme No (XY problem) (??), the MCU knows by user input. Basically the user plugs-in a sensor and selects it in software and then it is powered by 5V/3V3 | |
| Apr 6, 2021 at 14:06 | comment | added | mythbu | @TonyStewartEE75 I extended the description: Imax = 75mA, tolerance ±10%. | |
| Apr 6, 2021 at 14:03 | comment | added | Hearth | Why are you using the relay like that, instead of just using both terminals of a single pole? | |
| Apr 6, 2021 at 14:01 | history | edited | mythbu | CC BY-SA 4.0 |
added further details as requested in comments
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| Apr 6, 2021 at 13:04 | comment | added | Andy aka | Don't do what you don't need to do. | |
| Apr 6, 2021 at 13:01 | comment | added | SteveSh | And, how fast/how often do you need to switch between 3.3V and 5V? Relay might be the "best" solution if you only have to switch occasionally, and are ok with relay contact bounce and 10 ms switching time. | |
| Apr 6, 2021 at 12:53 | comment | added | D.A.S. | Or it could be an array of switches in a tiny package from Rohm that are addressable with the MUX or quad analog switches to supply mA and Mux uA sensor output (gold plated ones with Mil-Std 883 rating worth $$$) | |
| Apr 6, 2021 at 12:51 | comment | added | Bimpelrekkie | If you ask for the "best" solution, you have to list the features that you want and give them priorities. The "best" is of course the "ultraconduct-idealswitcher 2020-12" but yeah, it costs more than € 173000, are you willing to pay that? (Yes, I made this up). But this solution has mechanical implications (e.g. lifetime) No, it does not until you prove that it does and that your application needs a longer lifetime than a good relay can offer. | |
| Apr 6, 2021 at 12:49 | comment | added | D.A.S. | We assume you know which devices need Which voltages between sleep to a downstream Mux address, but you must say the loads | |
| Apr 6, 2021 at 12:48 | comment | added | Justme | Just to confirm that this is not a XY problem, may I ask why is switching of sensor supply between 5V and 3.3V needed in the first place? How would the MCU know which supply to select? | |
| Apr 6, 2021 at 12:48 | comment | added | D.A.S. | Neither a) or b) until you define V tolerance at I max of TBD sensors | |
| Apr 6, 2021 at 12:42 | history | asked | mythbu | CC BY-SA 4.0 |