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I'm building a modular 12 VDC system with individual modules that will step the voltage down to 5 V for powering a microcontroller and a grid of LEDs (4.5 A max per module). These modules can be added or removed from the system at any time. (see the bottom for additional project details)

This is the first time I've developed a hot-swappable system, and I worry about blowing out the modules. Will a good switching step-down voltage converter be enough?

I'm currently looking at the Richtek RT6255A DC-DC converter. The datasheet says:

To control the inrush current during the startup, the device provides a fixed 1.5 ms soft-start up.

Would this be sufficient? Do I need to worry about overvoltage blowing the DC-DC converter? Its maximum voltage is rated at 20 V. How do you approach systems like these?

I've been looking at some hot-swap controllers, like the RT1720, and would love any advice or recommendations you might have.

Additional details

This project is for an interactive LED dance floor installation (project page, original project)

  • The system will be powered by a switching 12VDC power supply rated at 100+ watts (connected to mains).
  • Each module can draw up to 4.5A each.
  • All modules will be within 5 meters of the main power supply.
  • In most cases, all the modules will be powered on at once. However, it's possible that some will be swapped in or out at any given time, but this would happen one at a time by hand.
  • It takes several seconds to connect or disconnect the modules because of the interlocking base they're built on.
  • Between modules, the power will be transmitted through blade-style battery connectors (787614-1 and 5787246-1 on Digikey)
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  • \$\begingroup\$ It depends on your 12 V supply a bit. What is it? Car battery? How distant from it are the modules? Hom many of them get plugged at the same moment? Besides that the version of the converter with SS pin for inrush control mitght be sufficient. Overvoltage, ESD etc. protection is another part of the problem. \$\endgroup\$
    – datenheim
    Feb 14, 2023 at 7:48
  • \$\begingroup\$ The system will be powered by a switching power supply rated at 100+ watts (connected to mains) and placed within 5 meters of all the modules. In most cases, all the modules will be powered on at once. However, it's possible that some will be swapped in or out at any given time, but this would happen one at a time by hand. It takes several seconds to connect or disconnect the modules because of the interlocking base they're built on. Between modules, the power will be transmitted through blade-style battery connectors (146845-1 and 5787422-1 on Digikey) \$\endgroup\$ Feb 14, 2023 at 17:39
  • \$\begingroup\$ What is the top consumption of a single module (the most power hungry one)? You may consider adding those details to your question by editing ;-) \$\endgroup\$
    – datenheim
    Feb 14, 2023 at 22:01
  • \$\begingroup\$ All modules are identical and can draw up to 4.5A each. There won't be a specific "power-hungry one." This is part of an interactive LED dance floor installation, so the current consumption per module will be dependent on the LED animations happening at that moment. \$\endgroup\$ Feb 15, 2023 at 1:18

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Most likely you would not need an additional hot-swap controller.

The corner-case is that the main dc/dc-converter needs to power-up against the maximum number of modules that are already connected. It must be able to start-up correctly with all the C_in of all modules in parallel.

Since you did not name the main converter this point may or may not be a problem.

Further down I'd recommend to use the 8-pin RT6255A.

That allows you to modify the soft-start feature in case 1.5 ms is too fast. As soon as you have dimensioned the C_in value one can start modelling the maximum inrush current and see if the main converter can withstand it.

It also allows you to enable your module after its converter reached running state by using the power-good pin.

You may even employ the enable-pin for a sort of sequencing of the modules converters.

Finally add ESD protection and usual EMC filtering. Done.

Depending on budget and quantity of devices you may also consider ready-made point-of-load modules such as Recom R-6 just as an example.

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  • \$\begingroup\$ Thank you for all your feedback and recommendations on this. \$\endgroup\$ Feb 16, 2023 at 0:01

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