Timeline for Different power supply layouts for ICs with 3.3V and 5V
Current License: CC BY-SA 4.0
18 events
| when toggle format | what | by | license | comment | |
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| Sep 8, 2021 at 17:41 | vote | accept | paulst | ||
| Sep 7, 2021 at 19:05 | comment | added | vir | There are also component selection concerns i.e. your primary converter might have wide input voltage range, robust protection/filtering, and get a lot of PCB real estate for heat dissipation while downstream converters - especially if they're running a light load - can be smaller and have fewer features. Boosting up from a lower voltage might then make sense overall. For what it's worth, I just finished a board with a primary 5V converter feeding downstream 3.3V and 2.8V converters and it works, but you'll need to take a look at your requirements and see what works best for you. | |
| Sep 7, 2021 at 19:04 | review | Close votes | |||
| Sep 22, 2021 at 3:11 | |||||
| Sep 7, 2021 at 17:47 | comment | added | D.A.S. | Also define power sequencing and if DC OK for UVP protection is required. Otherwise, you get lots of handwaving discussions. So assumptions ought to be defined with a range by you. | |
| Sep 7, 2021 at 17:40 | comment | added | D.A.S. | 6:1 Vin range ratio does lean in one direction for topology. Also state required efficiency and layout area allocated, isolated or non. | |
| Sep 7, 2021 at 17:33 | comment | added | D.A.S. | You can choose any topology that fits AFTER you define specs for current, Imax, dI/dt, ripple mVpp and % tolerances or min/max, input and output load regulation error, Temperature range, in a list, in your question. There is no universal solution, yet there are many. | |
| Sep 7, 2021 at 17:32 | history | edited | JRE | CC BY-SA 4.0 |
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| Sep 7, 2021 at 17:16 | answer | added | AnalogKid | timeline score: 0 | |
| Sep 7, 2021 at 16:59 | answer | added | hacktastical | timeline score: 1 | |
| Sep 7, 2021 at 16:41 | comment | added | Wesley Lee | I would say unless you have a specific reason to run a boost converter off a buck converter, use two buck converters in parallel. (some reasons might be as mentioned the dropout, another reason might be a high Vin, which would require more expensive IC's/caps and so on, so a single High Vin Buck + a boost might be cheaper/simpler than two high Vin bucks) | |
| Sep 7, 2021 at 16:39 | history | edited | Null♦ | CC BY-SA 4.0 |
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| Sep 7, 2021 at 16:36 | comment | added | DKNguyen | Downstream converters load the upstream converters they are connected to. So if you have a 10A supply, you probably want it running through minimal upstream converters, | |
| Sep 7, 2021 at 16:35 | comment | added | paulst | Thanks a lot, could you elaborate on how different currents affect the choice? In my specific case its going to be in the 100-400mA range for both. But I'm interested in the general case and the reasons for that. | |
| Sep 7, 2021 at 16:33 | comment | added | DamienWontContributeToAITheft | Another reason could be supply sequencing, eg. when the 3V rail must always be on before the 5V rail. | |
| Sep 7, 2021 at 16:28 | comment | added | DKNguyen | I would not say most common (far from it actually) but one reason to do that is dropout with a 6V input being unable to support 5V.. | |
| Sep 7, 2021 at 16:27 | comment | added | user16324 | To some extent it depends how much current you need on each rail. Which you haven't mentioned. You can make a case for any of those scenarios (and a couple of others) for different requirements. | |
| S Sep 7, 2021 at 16:24 | review | First questions | |||
| Sep 7, 2021 at 16:39 | |||||
| S Sep 7, 2021 at 16:24 | history | asked | paulst | CC BY-SA 4.0 |