Why 3.3V and not 5V?

I was wondering why 3.3v max input was decide on when so many sensors are 5 volt. I don’t know much about 3.3 vs 5 volt, the one thing I constantly keep running into is having to divide voltages down to make it 3.3 which just makes everything messy.

Coming from an arduino (5v) and not having to mess with dividers just to get a simple sensors to work, to having it become a huge pain/mess of resistors just to get sensors to work is rather annoying. There is probably a simple explanation for it, again I’m a noob in that area.

I love the photon and electron but honestly hate this part about them.

Again, admittedly I no nothing really about 3.3 vs 5. I’m happy to learn though.

TLDR: why are the input max voltage on the photon and electron so low (3.3V) when majority of sensors are 5volt.

Because the chip can handle only 3.3V. The sensors are kinda ‘old’. With things becoming more reliant on battery power, or power efficiency in general, lowering the voltage is a good way to save on power.
I also think it allows the chip to run cooler (but that might be complete non-sense, 'twas I while ago I think I heard that).

There are an increasingly large number of sensors that work on 3.3V just fine, so that shouldn’t really be an issue. Voltage deviders aren’t too hard either, and there’s dedicated hardware for level shifting available as well, if you really don’t want to spend effort on it.

Just so you know, voltages can go even lower, as some computer chips run under 1.5V already (if I’m not mistaken).

thanks for the feedback. Almost all analog, well priced sensors i find are 5 volt output, split core sensors, pressure sensors, thermistors etc. I just find that having to keep using stuff to drop the voltage makes my projects messy.

I see that my question may not be worded perfectly. I’m not talking about powering the sensor, just reading the sensor output voltage which is generally 0-5 volts.

As I read more on this I get the general idea that cost is basically the factor. A while ago I found that they didn’t include op amps on the photon or electron like they do on the ardunio because of cost (.20 cents).

I did grab the shield shield so maybe that will help get rid of my problems, the documentation is not very noob friendly for that unit lol.

Thanks again for the feedback, I’m here to learn :smile:

Here some more discussion: https://m.reddit.com/r/arduino/comments/1t20tb/why_is_33v_a_standard/

http://jeelabs.org/2010/12/16/voltage-3-3-vs-5/

Cost is not the reason in this case. It’s that the chip can only handle 3.3V. Technology has moved forwards, whereas the sensors you’re looking at apparently have not :wink:
There’s a variety of reasons why 3.3V is a better idea, and cost can be one of them.

Why would you need op-amps on the devices? I haven’t yet used one so far, and I’m doing just fine. On the odd chance that I do need to use one, adding an external one isn’t too bad. Including them on all board for someone who might need them, not the best choice really.

I get that Arduinos might be a bit more forgiving, but they’re also generally meant for learning, not for actual projects/products. Each has its merits :slight_smile:

You can even convert your arduino to 3.3v: https://learn.adafruit.com/arduino-tips-tricks-and-techniques/3-3v-conversion

This is why I needed an op amp: LM35 Temperature Sensor

Yeah if you want low cost reliable sensors, you go 5 volt, technology really hasn’t changed when it come to using a split core sensor lol. But I see your point: Use more expensive sensors or switch back to an arduino with a gsm shield.

I will have to disagree on the arduino not for real projects. Thanks also for the link to that thread, reading it now.

Nope, that doesn’t have to be true. There’s a variety of low cost digital sensors that perform equally as well, if not better, for the same prices or less. LM35 VS DS18B20 for example. Both can be had for less than $1.

If you’re referring to current sensors, then I believe it actually did. If I’m not mistaken, there are digital solutions for that that might be more accurate and cheaper than the analog counterpart. And even that analog version had to be ‘tuned’ to a specific voltage, be it 5 or 3.3

Then you’ve really misunderstood my point. 3.3V is used because that’s just ‘better’. You can make chips that are more efficient, yadayada, read the other threads on why.
The reason the photon uses 3.3V is because it has a chip on it that used 3.3V, makes sense, right?
Considering 3.3V is a perfectly reasonable voltage to use, there’s no reason to add 5V capabilities to that, especially not for that wacky single sensor that might not have a 3.3V counterpart.
3.3v sensors aren’t necessarily ‘more expensive’, and can even be cheaper due to the more efficient technologies used. And even if you do only have 5V sensors, you don’t have to ‘go back to arduino’. Use a voltage decider, or a level shifter, and you’re good to go. Do me a favor and check the operating voltage of the Arduino Due for me ;)?

Though you can most certainly stick a Uno R3 in a finished product, that’s not what they’re made for :wink: It’s certainly moving in that direction with different variations (using 3.3V), but you get the point (I hope) :wink:

Technically you can get the DS18B20 for free if you request a free sample. I got 10 of them the other week after filling out a form that said I wouldn’t let them leave the U.S. You have to have a private email address as well; no google/yahoo/etc domains. https://www.maximintegrated.com/en/storefront/storefront.html You’ll likely want the standard DS18B20, with nothing after the 0. (Its the breadboard friendly package; the PAR versions are parasite power only which you can also do with the normal version). By default it’ll put 2 in your cart but you can edit that number. You can get many other types of chips as well but you have to know the part number, just look through the product catalog on the same page (left nav) to figure that out.

Thanks for the info, I’m not in the US though. When I refer to cheap 5 volt sensors I didn’t mean the LM35. I’m talking about 200-300 dollar industrial 5 volt sensors.

Thanks for the feedback.

When I refer to cheap 5 volt sensors I didn’t mean the LM35. I’m talking about 200-300 dollar industrial 5 volt sensors for prototyping.

“Do me a favor and check the operating voltage of the Arduino Due”

Really?. We are talking about the Uno, and you pick out the one 3.3v board, you know the voltage of that board as well as I do, come on man.

Then you’ve really misunderstood my point. 3.3V is used because that’s
just ‘better’. You can make chips that are more efficient, yadayada,
read the other threads on why.
The reason the photon uses 3.3V is because it has a chip on it that used 3.3V, makes sense, right?
Considering
3.3V is a perfectly reasonable voltage to use, there’s no reason to add
5V capabilities to that, especially not for that wacky single sensor
that might not have a 3.3V counterpart.
3.3v sensors aren’t
necessarily ‘more expensive’, and can even be cheaper due to the more
efficient technologies used. And even if you do only have 5V sensors,
you don’t have to ‘go back to arduino’. Use a voltage decider, or a
level shifter.

You are clearly offended by my post and think its an attack on particle. Good day Mr “Elite”

@Keaner I’m not sure @Moors7 took offense or, like you, is somewhat fervent. The issue of 3.3v vs 5v can be vexing, especially when it comes to sensors and peripherals. More and more platforms are moving to 3.3v including the Arduino Due and the new Arduino Zero. Also include the amazing Teensy products and the list goes on. In fact, I am working on boards where the battery powered devices are operating at 1.8v to keep power consumption as low as possible. This forum is full of the “I have a 5v sensor so how can I make it work” questions. All that to say that there is no simple answer. However, I can say that sensor manufacturers have been slow to adapt to the new low voltage, battery operated and wearable world.

Interestingly, as I write this response, I realize there is an opportunity for a “level-shifter-like” board but for analog signals going to/from particle devices. Ultimately, your requirements should point to the most suitable platform for your application, including sensors. If you chose Particle, please use this forum to ask for help on any interface challenges you may have. You’ll find this community very creative! :smile:

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Keaner,

In basic terms, as you increase the number of discrete components while continuing to reduce the chip size the widths of the conductors and the insulation between them get smaller. The higher the voltage the more leakage current you have between the conducting traces inside the chip. If the voltage gets to high you will fry the chip.

As an example the quad core in my computer is running on 1.136 vdc,

Also I think the point that @Moors7 was trying to make was even the newer Arduinos are operating at lower voltages.

One other choice is to use something like a ADS1115 module that is a 16 bit ADC with four channels (I2C connected).

There are companys that make a board for the Photon or Electron that provide level shifted (to 5 vdc, I2C standard voltage) and ADS1115 module at very reasonable prices.

Chuck

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@peekay123, your response reminded me of days gone by when we used higher voltages for sensors to over come line losses between the sensor and the transmitters. That was one of the reasons that a lot of sensors use 4 to 20 milli amp outputs instead of voltage output.

Chuck

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Thanks for that, great info!

CPUs are my language so that’s easy to understand reference.

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I think that’s what @Moors7 meant when he said

The STM32F family of micro controllers (that’s the CPU here) is running 3.3V and hence the whole board is set for that, while the older AVR chips used on the older Arduinos are 5V cores.

I’m absolutely sure @Moors7 didn’t mean to offend you in any way (and I can’t really read that into his response either).

For the disagreement about this

What @Moors7 most likely refered to was that you won’t find a lot of products with a production run of 1000+ based on an actual Arduino board while there are several products based on a Photon/P0/P1 board, since that’s what Particle has targeted them for.

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