Arduino mini pro 328p 16Mhz Voltage

Click For Summary

Discussion Overview

The discussion revolves around powering an Arduino mini pro 328p 16MHz microcontroller board with a 3.7V battery, exploring the feasibility of operating the board at lower voltages than specified. Participants examine the implications of using a step-up converter versus running the board directly at lower voltages, as well as the specifications and design choices of the board.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that the Arduino mini pro has two versions, one designed for 3.3V and another for 5V, and question the necessity of the higher voltage for certain applications.
  • There is discussion about the possibility of powering the board at 3.0V, with one participant reporting successful operation at this voltage with minimal current draw.
  • Questions are raised about the specifications in the datasheets for the components on the board and whether the 5V input is primarily for convenience.
  • Some participants suggest that the Brown-Out Detection (BOD) setting in the Arduino IDE could be adjusted to allow for lower voltage operation.
  • Concerns are expressed about the reliability of operating the board at lower voltages, with references to the safe voltage range for the microcontroller and the potential impact of temperature and component variability.
  • There are inquiries about the role of the SJ1 jumper and whether it can be removed to allow for direct powering with a lower voltage supply.
  • One participant mentions that the pro mini board is outdated and suggests alternatives like the Nano or programming an ATmega chip directly.
  • Another participant points out that while the microcontroller can operate at voltages as low as 2.7V, the overall design and connected components may dictate the need for a higher voltage.
  • Discussion includes the potential for using a step-up regulator if maintaining a 16MHz clock frequency is necessary, along with suggestions for creating a custom PCB to avoid power loss from onboard regulators.

Areas of Agreement / Disagreement

Participants express a range of views on the feasibility and reliability of powering the Arduino mini pro at lower voltages, with no consensus on the best approach. Some support the idea of operating at 3.0V, while others emphasize the importance of adhering to specified voltage ranges.

Contextual Notes

Participants note the lack of information regarding certain components like the SJ1 jumper and the implications of using different voltage levels on the performance and reliability of the board.

Who May Find This Useful

This discussion may be useful for hobbyists and engineers interested in low-power applications, Arduino projects, and those exploring alternative power supply options for microcontroller boards.

andymag
Messages
11
Reaction score
3
Hi guys,

I am currently building a small device that is to be powered by a 3.7V battery and is run by an Arduino mini pro 328p 16Mhz microcontroller board. This board is to be powered by a 5V power supply according to the specifications. So I would need to add a step up converter, although I would like to avoid it.

Today, out of curiosity I tried to power the board (with only an oled display attached) by an adjustable DC power supply. At 3.0 Volts it seemed to work fine and drew only 20 mA. I incremented a number from 0 to 1000 without delay() in the code and it was done counting in one minute, which is the same time as it needed powered by USB.

Does anyone have experienced with powering 328p 16Mhz with only about 3V? I would love to avoid building in a step up converter but not sure how it behaves in some complex applications.

Any help is appreciated. Thanks a lot in advance.

Andy
 
Computer science news on Phys.org
What do the datasheets for all of the components on the PCBA specify? Is the 5V input only used because it's a handy USB voltage? Is there a 5V to 3.3V step-down converter right after that 5V input? Do you have the schematic for the Arduino board?
 
The specs page for Arduino pro mini says that they had two boards, one at 3.3V, and another at 5V. If you have the 5V board, it appears that they want it to be powered at 5-12V. However, there should be an option for BOD in the Arduino IDE. You can lower that value and then experiment a bit on whether the board will work at a lower voltage. For example, on a Uno or Mega board, the BOD can be set to as low as 2.7V.

@berkeman The schematics are available on the linked page, if you would like to give them a look.
 
Wrichik Basu said:
@berkeman The schematics are available on the linked page, if you would like to give them a look.
Thanks Wrichik; I'll have a look later today. What's BOD?
 
berkeman said:
What do the datasheets for all of the components on the PCBA specify? Is the 5V input only used because it's a handy USB voltage? Is there a 5V to 3.3V step-down converter right after that 5V input? Do you have the schematic for the Arduino board?
Hi berkeman, thanks for the fast reply. There is a Linear Voltage Regulator. However, it regulates down only to 5V: https://www.lcsc.com/product-detail..._Microchip-Tech-MIC5205-5-0YM5-TR_C70431.html.

There are two versions of pro mini: 3.3V and 5V. I definitely have the 5V version.

On the other hand, I do not see any obvious component on the board that would require 5V. Some LEDs, a bunch of capacitors and resistors. shotky diode and a ceramic resonator. The IC seems to accept a wide range of input voltage: https://www.lcsc.com/product-detail...SOCs_Microchip-Tech-ATMEGA328P-AU_C14877.html

Below are the official arduino schematics and a third party BOM:
1709828857005.png

1709828999487.png



I am really wondering why Arduino would produce two different versions.
 
Does the documentation say anything about SJ1 (the output jumper for the regulator)? It looks like the circuit runs on 3.3V but the regulator just lets you bring in whatever higher voltage is convenient for you. You may be able to remove SJ1 and power Vcc with your 3.3V supply. What range will your "3.7V" battery range over from full charge to low battery?
 
Wrichik Basu said:
The specs page for Arduino pro mini says that they had two boards, one at 3.3V, and another at 5V. If you have the 5V board, it appears that they want it to be powered at 5-12V. However, there should be an option for BOD in the Arduino IDE. You can lower that value and then experiment a bit on whether the board will work at a lower voltage. For example, on a Uno or Mega board, the BOD can be set to as low as 2.7V.

@berkeman The schematics are available on the linked page, if you would like to give them a look.
Hi W. Basu, thanks. However, as I said it works with 3.0Volts. I just would like to understand if it is reliable. There must be a reason why they made different versions of the board. Maybe earlier the ICs from atmega were different and did not accept a range of voltages.
 
berkeman said:
Does the documentation say anything about SJ1 (the output jumper for the regulator)? It looks like the circuit runs on 3.3V but the regulator just lets you bring in whatever higher voltage is convenient for you. You may be able to remove SJ1 and power Vcc with your 3.3V supply. What range will your "3.7V" battery range over from full charge to low battery?
unfortunately, there is no info regarding SJ1. At least, I have found nothing.
 
berkeman said:
What's BOD?
Brown-Out Detection.
 
Reply
  • Informative
Likes   Reactions: berkeman
  • #10
andymag said:
I am currently building a small device that is to be powered by a 3.7V battery and is run by an Arduino mini pro 328p 16Mhz microcontroller board.

andymag said:
There are two versions of pro mini: 3.3V and 5V. I definitely have the 5V version.

Er, why? Can't you just buy a 3.3V board?
 
Reply
  • Like
Likes   Reactions: berkeman
  • #11
pbuk said:
Er, why? Can't you just buy a 3.3V board?
The pro mini board is outdated and no longer produced. The alternative would be to use Nano, or maybe directly program an ATmega chip using another Arduino board via the Arduino as ISP protocol (which is what I do to reduce costs).
 
  • #12
According to datasheet, the uC itself can run with anything from 2.7V to 5.5V, so I guess it's the environment what makes the difference between a 3.3 or 5V board: LEDs, attached devices and such.

If you can properly keep in mind that you have 3.3 instead of the 5V as VCC then I think it should be just fine.
 
Reply
  • Like
Likes   Reactions: Wrichik Basu
  • #13
The datasheet for the processor includes this graph for the safe maximum clock frequency for a given supply voltage:

speed grades.png



It works out to a minimum safe voltage of 3.78V at 16MHz. You can get away with operating outside the safe zone but, you know, maybe sometimes it won't work depending on the particular part or maybe the temperature or who knows.
 
Reply
  • Informative
  • Like
Likes   Reactions: Rive and berkeman
  • #14
andymag said:
unfortunately, there is no info regarding SJ1. At least, I have found nothing.

That's there so you can power directly (e.g. with a battery) to VCC instead of RAW. That way you don't incur the power loss from the probably inefficient voltage regulator. Usually for low power you'd choose something less than 5V and instead of a 16MHz crystal you'd use the processor's internal 8MHz oscillator.

But if you really need 16MHz then to be safe you'll have to add a step up regulator. Pololu sells some pretty tiny and inexpensive ones. In that case you would also want to cut SJ1 to leave the unneeded onboard regulator out of the picture.

At some point it's easier to just make your own PCB. It isn't that hard to hand solder one of those processors.
 

Similar threads

Arduino board works on one computer but not another
  • · Replies 2 ·
Replies
2
Views
5K
Some basic questions about the Arduino UNO
  • · Replies 31 ·
2
Replies
31
Views
3K
DC-DC conv. Ripple affecting Speech Recognition - Capacitance multiplier
  • · Replies 22 ·
Replies
22
Views
2K
Buck Converter with USB-C output
  • · Replies 2 ·
Replies
2
Views
2K
How does a voltage regulator differ from a zener diode?
  • · Replies 38 ·
2
Replies
38
Views
5K
Cortex M4 sinking a lot of current
  • · Replies 3 ·
Replies
3
Views
2K
Implementing microcontrollers (AT89C51-24PC)
  • · Replies 18 ·
Replies
18
Views
4K
Reading the Arduino Schematic (for a Beginner)
  • · Replies 8 ·
Replies
8
Views
18K
How to make a custom UPS using an old PC power supply and 18650 batteries?
  • · Replies 7 ·
Replies
7
Views
3K
Potentiometer alternatives
  • · Replies 14 ·
Replies
14
Views
8K