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.