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Topic: At what Voltage does the 328P stop working? (Read 140 times) previous topic - next topic

josephchrzempiec

Hello I'm making a oled clock using the atmel 328p chip and a oled as well as the DS3231. I understand hwat voltages it needs to be on the oled and RTc- Real timeclock chip the min voltage but not sure about the 328p chip?


Joseph

Shpaget

#1
Jan 27, 2015, 09:04 pm Last Edit: Jan 27, 2015, 09:05 pm by Shpaget
Depending on the frequency you run it at and the fuse settings, 1,8 to 5,5V.
You can find more details in the datasheet.
http://www.atmel.com/images/Atmel-8271-8-bit-AVR-Microcontroller-ATmega48A-48PA-88A-88PA-168A-168PA-328-328P_datasheet_Complete.pdf

josephchrzempiec

Well i don't need much speed it will only be running the DS3231 RTC - Real time clock chip and the blue/yellow Oled screen. so i was thinking of keeping the default speed it comes with the bootloader on it for the arduino.


Grumpy_Mike

Quote
so i was thinking of keeping the default speed it comes with the bootloader on it for the arduino.
Changing the speed ivolves changing the crystal and the bootloader software, it is not an easy task.


josephchrzempiec

thank you Grumpy Mike i would keep it at default speed. But Just trying to figure out at what voltage does the 328p chip it's self power down if there is not enough Voltage going to it?

MarkT

Brown out fuses select the brown-out detector voltage.
[ I won't respond to messages, use the forum please ]

Grumpy_Mike

Quote
But Just trying to figure out at what voltage does the 328p chip it's self power down if there is not enough Voltage going to it?
That is not how it works. It just stops working, there is no power down.
A brownout is a trigger that can cause an interrupt to happen but it is that software that must do something.

josephchrzempiec

The reason isbecause I'm working on a lcd clock and i got a lipo battery on it  and  i bought a module that monitor how much power is on the battery. Why I'm asking is beucase i want to know how low will power gets before i had to charge it.  I'm just trying to get a idea of at what voltage level do i need to charge the battery at thats all.

CrossRoads

At 16 MHz, the default speed unless you change fuses, you need ~3.8V to stay within spec. You shouldn't let LiPo  go below 3.7V. They get damaged when they are overdischarged.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

PeterFW

#10
Today at 04:57 am Last Edit: Today at 08:48 am by robtillaart
You shouldn't let LiPo  go below 3.7V. They get damaged when they are overdischarged.
When cuting of at 3.7V you waste most of the cell capacity.
Allmost all modern Li* cells are perfectly safte to discharge to at least 3V without battery damage or infinging upon the charge/discharge cycle count of the cell.

I have to 3 different types of genuine panasonic and sony cells, the datasheets rate the nominal voltage at 3.6V for each cell and the discharge should be stopped at 3V.

josephchrzempiec

thank you all for the information it help me a lot.

MarkT

That is not how it works. It just stops working, there is no power down.
A brownout is a trigger that can cause an interrupt to happen but it is that software that must do something.
It switches to reset mode (low power), not an interrupt.

The B.O. reset can timeout and then the device springs back to life - I'm not sure
what the current bootloader/fuse settings do.   Assuming I've read the datasheet right!
[ I won't respond to messages, use the forum please ]

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