Arduino pro mini operating temperature

Hi there, I have been experimenting with different ways of powering the pro mini, it is imperative that I get a stable 5v for the TMP36 sensor to work and for the logic levels to be correct for timings etc (it is being used as an in car gauge for RPM, speed, fuel level, water temp).

I have tried direct USB power from the car (which gives a stable 5.06v) and wired it straight to the VCC input on the mini. The current drawn at this state is 1.1mA. I get an operating temp of 50 degrees celsius taken from the processor. Currently it is powering a small OLED screen and a TMP36 sensor, with 12v inputs for RPM and speed. Is this temperature to be expected for the processor?

If I use the RAW input at 5.06v, my readings get distorted as I think the voltage drops too much through the regulator, so I have to use the VCC input. When I do use the RAW input, it reaches the same temperature anyway so it doesn't make a difference.

I also have an external voltage regulator (LM7805C) which I used for a 12v input, this is also wired in. When I use this the regulator, its gets to 65 degrees and the pro mini gets to 50 degrees again. I still have to drive an H-bridge chip and shift register to wire in so the load on the pro mini will increase a little. Ideally I want this to be at ambient temperature so maybe the simple solution is to use a suitable heat sink, can anyone recommend an effective one?

So what I would like to know is...is this is safe operating temperature for the pro mini and will it be okay for prolonged use (say 5-6 hours) at this state.

Thanks, Brian

adderall00codine: I have tried direct USB power from the car (which gives a stable 5.06v) and wired it straight to the VCC input on the mini. The current drawn at this state is 1.1mA. I get an operating temp of 50 degrees celsius taken from the processor. Currently it is powering a small OLED screen and a TMP36 sensor, with 12v inputs for RPM and speed. Is this temperature to be expected for the processor?

50 deg. C sounds far too hot to me.

What do you mean by "it is powering..."?

if the microcontroller chip is hot by self-heating, you push it to hard (too much current) if the source is the power regulator, its OK for the microcontroller. I'd try feeding the extermal components from other source than the pro mini itself

For every 10 degrees C extra you run any piece of electronics the life of it approximately halves.

fungus:

adderall00codine: I have tried direct USB power from the car (which gives a stable 5.06v) and wired it straight to the VCC input on the mini. The current drawn at this state is 1.1mA. I get an operating temp of 50 degrees celsius taken from the processor. Currently it is powering a small OLED screen and a TMP36 sensor, with 12v inputs for RPM and speed. Is this temperature to be expected for the processor?

50 deg. C sounds far too hot to me.

Fot ATmega168/328 maximum ratings Operating Temperature.................................. -55 C to +125

zaxarias:

fungus:

adderall00codine: Is this temperature to be expected for the processor?

50 deg. C sounds far too hot to me.

Fot ATmega168/328 maximum ratings Operating Temperature.................................. -55 C to +125

Um, the question was: "Is this temperature to be expected..."

it depends , but i think yes..

zaxarias: it depends , but i think yes..

I don't know exactly what you do with your chips ... but I say no. I've never had an AVR chip hot enough to burn a finger in normal use.

As I said earlier: If it is the MCP that is the source, its probably VERY much hotter at one point inside. Find the cource and take action..

fungus:

zaxarias: it depends , but i think yes..

I don't know exactly what you do with your chips ... but I say no. I've never had an AVR chip hot enough to burn a finger in normal use.

...Talking about the chip...

Well that's what ATmega says : Temperature Range: -40 C to 85 C So i don't see a temperature of 50C possible to cause any trouble.. It's between normals..

Also maximum operating temperature is : -55 C to +125 C , which is not even close to that.

AVR chips that have an internal temperature sensor: ATmega8 : No ATmega8L : No ATmega8A : No ATmega168 : No ATmega168A : Yes ATmega168P : Yes ATmega328 : Yes ATmega328P : Yes ATmega1280 (Arduino Mega) : No ATmega2560 (Arduino Mega 2560) : No ATmega32U4 (Arduino Leonardo) : Yes "The internal temperature is the temperature inside the chip, just like the cpu-temperature of a computer. If the Arduino is not sleeping, this temperature will increase. If output pins are used to drive current (for example to drive a led) the internal temperature increases more. "(it depends the load) " Most newer AVR chips have a temperature range up to 85 degrees Celcius. The Arduino could be used to switch off the device or to switch off itself at 80 degrees Celcius. " http://playground.arduino.cc/Main/InternalTemperatureSensor

Sorry but i can't find anything indicating 50C a dangerous temperature, at least for the ATmega....