## How to operate working voltage Atmega 168PA ?

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Hello forum experts,

Is it possible that to set working voltage 5 Volt for  Atmega 168PA MCU like a brown-out detection?

What does it say in the datasheet about brown-out detection?

and tell what you mean by "set working voltage".

If your nominal Vcc level is about 5 volts then you would use the trip level below that, about 4.4V.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

If nominal Vcc level drops 4.9Volt, mcu should be off. Is it possible to do it?

Casper_0770 wrote:
If nominal Vcc level drops 4.9Volt, mcu should be off. Is it possible to do it?

Not using the in-built BOD.

I guess you could do something like use the ADC to read the Vcc voltage and put the micro to sleep if it falls to your 4.9V level.

#1 Hardware Problem? https://www.avrfreaks.net/forum/...

#3 All grounds are not created equal

#4 Have you proved your chip is running at xxMHz?

#5 "If you think you need floating point to solve the problem then you don't understand the problem. If you really do need floating point then you have a problem you do not understand."

Last Edited: Wed. Dec 5, 2018 - 03:24 PM

I would help us if you explained why you need this, then we could provide better answers to your questions.

Also when you say "off" do you mean off as in powered down, or just placed into a low power mode, or held in reset?

Jim

Yes exactly, I am looking for simple way without using ADC to read the Vcc voltage like brown out detection.

Problem is that brownout is NOT very precise and you do not have many choices.

For example, on the M168, the highest BODLEVEL is 4.3V and that can vary from 4.1V to 4.5V. The BrownOut Detector also takes extra  power.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

Casper_0770 wrote:

Must be a language issue, as the ADC is the simple way to "read" the VCC voltage???

Again it would help to know "why" you need to "read" the VCC voltage!

What is the context of the project?

Jim

Gas sensor works for 5 voltage. If voltage is less than 5 voltage, anolog is going up without sensing gas. So, I must avoid this issue.

Casper_0770 wrote:
Gas sensor works for 5 voltage

why do I feel like a dentist pulling teeth?

Jim

Last Edited: Wed. Dec 5, 2018 - 07:36 PM

Thanks for the link, I have worked with similar sensors.

It's the heater circuit that is critical that it maintain a constant voltage.

Two ways to monitor that would be to use the ADC against the internal band gap reference or

use the internal analog comparator to signal when voltage drops.

Set up your software to monitor which method you prefer to use.

Why is the heater voltage changing?  Is this a battery powered project?

Jim

edit AC

Last Edited: Wed. Dec 5, 2018 - 08:30 PM

Yes, I used lithium ion battery.