Powering a project - overvoltage protection and voltage regulators

S

StuB

New member
What's the best way to power 5v small, medium and large projects, say less than 1A, up to 3A and up to 10A?

If you have a 5V regulated power supply is it OK to just use that (I understand about cutting the track between USB 5V and VIN) or are you better off using a higher rated power supply and then using an onboard regulator to bring it back down? This just seems a little wasteful.

Are branded 5V USB phone chargers generally regulated well enough to use directly for small projects, the ones I've checked have been between 4.95V and 5.1V and haven't seemed to deviate much?


I have a project using a Teensy 4.1, Prop Shield LC, 176 x WS2812B leds, 1.8" ST7735 LCD and it uses the USB host.

It's all connected up and working great and I've been very impressed with the hardware so far.

When it's at idle (Teensy running at 150Mhz) with the LCD on but no LEDs it pulls about 170ma.

I understand the LEDs could pull up to about 13A however it's main use only needs up to 20 LEDs lit at the same time and the brightness set to 60 (out of 255 via FastLED) is about the right amount of light.

I've implemented power limiting in FastLED to restrict total power usage and including everything it pulls about 0.45A and that's worked well for testing and will actually be sufficient for most usage.

I've had it running from a USB phone adapter and my bench power supply.

I'd like to increase the power limit to allow for about 1.5A if needed so I need to sort out a suitable supply.


The main thing I'd like to protect is the device plugged into the USB Host, from what I can see this takes it's power from the Teensy 5V which looks to take it directly from the main 5V feed in from the power supply.


So can I rely on a decent USB phone charger staying within USB voltage spec and supplying up to 1.5A?

Should I be using a higher rated power supply and then a step down converter? I have a couple of the 5A cheap XL4015 ones available to hand can they be relied upon?

Do I need a separate specific high quality power supply and if so does anyone have any specific recommendations?

Do I need a separate over voltage or spike protection for the Teensy and therefore USB host supply?

All supplies assume bringing the power into a box and then separating the supply wires to the LEDS and the Teensy.
 
I typically use MeanWell constant-voltage supplies for my projects, and I have had very good luck with them. You can get them in various form factors, with and without cases, etc. If most of your hardware operates at 5V and only the Teensy has to regulate down to 3.3, then I wouldn't worry about any 'inefficiencies'.

Frank
 
paynterf said:
I typically use MeanWell constant-voltage supplies for my projects, and I have had very good luck with them. You can get them in various form factors, with and without cases, etc. If most of your hardware operates at 5V and only the Teensy has to regulate down to 3.3, then I wouldn't worry about any 'inefficiencies'.

Frank
Click to expand...

Thanks for the reply Frank.

Meanwell look to have a lot of products although after a quick look not that many seem to be 5v, most seem to be 12v or 24v.

I suppose my main question is, is it sufficient to rely on a decent power supply like one of the Meanwell ones to reliably supply a constant voltage or do you need some other form of protection?
 
IMHO, as long as you select a power supply with sufficient power (in Watts) for your project, you'll be fine. For instance, if your project consumes 1A at 5V, you need a PS capable of delivering 5W - and I typically multiply by 2 (or 3). So I would look for a MeanWell power supply in the 15W category, maybe like this one. Meanwell groups their units by power, and offers many voltage output options within each power level.

Take a look at [URL="https://www.fpaynter.com/2020/06/lab-power-supply/".]this project post [/URL]where I use an open-frame 24V supply for a lab power supply project.

As always, YMMV

Frank
 
Thanks again for the reply.

Looking at the voltage and load specs of those supplies (both +-5% on the 5V version) it says that they should always stay in range of 4.5v to 5.5v at the worst case scenario so this should be OK to feed straight in to the Teensy and lights assuming they're reliable.

Also your bench power supply project looks great.
 
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