0
\$\begingroup\$

I just started my first PCB and I have a question. I want to use two servos (SG90s) and a 5 V regulator powered from a 7.4 V battery.

After all my calculations the temperature that is dissipated is 160°C, but that's the thing I can not understand. My first prototype that I made was done using the same servos and an Arduino Nano, and I didn't have any problem with overheating or something like that. Are my calculations bad or will my LM1117 be fried?

This is my configuration:

enter image description here

My calculations:

enter image description here

\$\endgroup\$
4
  • 2
    \$\begingroup\$ How did you arrive at 160 degrees? How much power do you expect the servos to draw? \$\endgroup\$
    – JRE
    Commented Aug 13, 2022 at 21:05
  • 1
    \$\begingroup\$ You can't calculate temperature without having some information on heatsinking, so, where did you get 160 °C from? \$\endgroup\$
    – Hearth
    Commented Aug 13, 2022 at 22:00
  • 1
    \$\begingroup\$ We don't know how you ended up with 160 degrees C. It would help to see what formulas you used and what values you plugged in to come up with 160. \$\endgroup\$
    – Justme
    Commented Aug 13, 2022 at 22:09
  • \$\begingroup\$ Hi! I will post my calculations here. imgur.com/fI6Xbjv In fact i want to use those SG90S servos to move a 3D printed device using a PID. Link for SG90S: smart-prototyping.com/MG90S-9g-metal-gear-digital-servo.html \$\endgroup\$
    – GMW
    Commented Aug 14, 2022 at 8:20

1 Answer 1

3
\$\begingroup\$

Those wee RC servos don't draw anything like 550mA on a continuous basis under normal conditions. If they did, they'd quickly burn up. They can, however, draw more than 550mA when stalled or when starting. From this website:

enter image description here

So if they're lightly loading and running 10% of the time, the average current might be more like 15mA than 550mA.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.