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BlueESC 5V regulator overheating


(Alexander) #1

Hello, All. I have found that the 5V regulator in the BlueESC design runs at ~80-100C during normal operation. The regulator uses a SOT23-5 package; with 25Vin, 5Vout, and a combined load of ~20mA, the unit is dissipating almost 0.5W in a very small package - the device specs confirm an expected temp rise of ~80C at the junction. Could you please verify the PN and package of the voltage regulator suggested for this design? Thank you in advance, -Alex


(Rusty) #2

Hi Alexander,

The 5V regulator does run pretty hot. 25V is really high for the input voltage. I wouldn’t recommend going higher than about 18V to minimize heat. Also, the MOSFETs are not designed for gate voltages over 20V. The BlueESC uses thermally conductive potting compound and an aluminum case in water to draw heat away from it as quickly as possible.

If your application doesn’t have sufficient cooling then I’d recommend using a larger package that can handle the dissipation.

-Rusty


(Alexander) #3

Rusty, thank you for the info. The BlueESC specs (http://docs.bluerobotics.com/bluesc) indicate a maximum bus voltage of 22Vdc; it appears that all components with the exception of the MOSFETs are capable of operating with a 25Vdc bus. I agree that, in the original application, the potting and case provide adequate cooling even for the SOT23 package. I intend to use a larger package, with integrated heatsinking, in the next design revision. Thanks again!

 


(Alexander) #4

Rusty, one more question - are you running your ESCs with a 8MHz, or 16MHz oscillator? I ask because the processor current changes significantly based on clock speed, and may be contributing to my LDO heat issues. Cheers & thank you again for the help,


(Rusty) #5

Alex,

We’re using 8Mhz on our most recent design to help reduce power consumption. The currently published BlueESC designs use 16 Mhz.

-Rusty


(Lawrence) #6

So question, I was looking at the Multistar high capacity batteries and there are 4 cell and 6 cell versions. Normally I would look to the higher voltage but the Blue ESC says 22 volt max and a 6 cell pack is 22.2 volts. I am guessing from the spec and the above conversion that I really should consider the 14.4 vole 4 cell packs instead.


(Rusty) #7

Hi Lawrence,

I would definitely recommend sticking with the 4s batteries. Most of our components are not rated for use with 6s batteries.

-Rusty