Temperature of PROPMINI..
denno
Posts: 227
in Propeller 1
Probably a question for the designer of the PROPMINI. But, with the 3.3 volt and the 5 volt regulator on the board, and the input voltage between 6.5 and 12 volts, I was wondering what the maximum board temperature would be. Temperature is taken with an infered heat gun. I do know the temperature will vary depending on the input voltage. Higher temperature with the higher input voltage, I understand. Also, I know it depends on what else I am running on the 3.3volt and 5 volt supplies of the PROPMINI. The thermostat that I designed in another thread, with photos, draws about 190 mA's.
With about 11 volts in, I was running a board temperature of 130 degrees F. Dropping the input voltage to 6 volts, reduced the board temperature to about 90 degrees.
Any thoughts from the designers of the PROPMINI, or anyone in the know...about the maximum board temperature.
Thank you...DenO
With about 11 volts in, I was running a board temperature of 130 degrees F. Dropping the input voltage to 6 volts, reduced the board temperature to about 90 degrees.
Any thoughts from the designers of the PROPMINI, or anyone in the know...about the maximum board temperature.
Thank you...DenO
Comments
I'm pretty sure the PropMini uses linear regulators so it drops the voltage by converting it to heat.
If you assume the 3.3V regulator uses all the 190mA then you need to get rid of about one and a half Watts of heat.
With a lot of air flow, the temperature would likely be not much above ambient. With no air flow, it could probably get hot enough to shut itself off.
You might want to think of adding a switching regulator so you don't have to get rid of as much heat. You could either drop the 11V to 6.5V using a switching regulator. If you don't need super clean 5V power, you could bypass the 5V regulator and use a 5V switching regulator for you 5V needs.
It's pretty common in Propeller projects for people to use a switching regulator for the 5V line but then use a linear regulator for the 3.3V line. Linear regulators tend to be quiet compared with switching regulators.
Any thoughts and thank you again..deno
When I make my own PCBs which include a PropPlug interface, I add an extra pin next to the ground pin to allow the board to be powered from USB. "VCC" is 5V on this device (there is a 3.3V regulator on the bottom of my PCB).
You could probably use the USB to serial shown in the photo to power the PropMini. I think connecting to the 5V line, from the USB to serial PCB, to the PropMini's 5V line would provide enough power for the PropMini.
Some of these other USB to serial devices require a capacitor in series on the DTR line. On some devices the reset doesn't trigger correctly without the extra capacitor in series. The board in the photo includes this capacitor. The capacitor may be bypassed with a jumper when using a normal PropPlug or other device which doesn't need the capacitor.
Do you mean not enough juice for powering an application and talking to the chip or just for programming only ? The former is quite clear, the later - I'm not so sure.
I think this depends on the device used. I generally use the 5V from the USB and use my own 3.3V regulator (on the bottom of the PCB in the above photo). However I think some USB to serial devices can provide enough current for modest Propeller applications. Apparently the CP2102 can source 100mA of current on the 3.3V output.
Some USB to serial devices (like the one in the earlier photo) include a solder jumper to allow one to use either 5V or 3.3V on the VCC pin.
Your choice, but be warned.
Are you talking about programming the EEPROM on a test bench, and using another power source in an end product ?
The Prop1 data has Icc curves and data, and you should be fine programming EEPROM, using a lower current power source than would be needed to run all cogs at 80MHz
P1-reading-EEPROM currents indicate about 2.4mA and additional write currents needed by EEPROM itself are 3~5mA ballpark MAX specs
Regulators are quite cheap, and ones with Power-GOOD are becoming more common, so you are better to spread hings thermally and use a PG regulator in a final product design.
That is so odd. The Propeller is receiving all its power from the data pins.
I'm not sure, but I have a hard time believing powering the PropMini this way is good for PropPlug. It might not be good for the Propeller chip as well since all the power is is being supplied through the I/O rather than power pins. The Propeller chip is sensitive to how it is powered. It's not very hard to blow the PLL circuit on the chip (I've done so many times).
Cluso99..you are correct, as the download times out on loading the RAM not the EEPROM. As soon as i supply 5volts to Vin on the propmini, the download completes.