Jump to content

Stellaris launchpad power options

Recommended Posts

Hello, i wanted to ask what power options I have to power Stellaris Launchpad.


I read on official site that i can use one of the micro USB ports but are there any others ways that i cant power it with baterries and make it more portable ?


As i read in this article



.. The Launchpad expects 4.75-5.25 VDC on VBUS, ...




So does this mean I can connect 5V supply to VBUS on my board and power it from there without making any damage or having to cut the board as mentioned in article ?


Thanks for reply

Link to post
Share on other sites

My power source was a 11.1V LiPo-Battery with a linear regulator (common 7805 thingy) which outputs about 5V (it was something like 4.9V, so well within the required range).


What exactly do you want to do and what are your requirements?



I was just wondering what options I have, I think i will do the same as you because i will also need 11,1V battery for running motors, so using regulator on 5V will be also my choice ... thanks for help :)

Link to post
Share on other sites
  • 3 months later...

Would it be possible to power it with a 7V Lithium ion battery behind a 5 V voltage regulator? I only see mention of LiPo batteries.

Yes, but you have to keep in mind that the 7.2V is only the nominal voltage rating, when the battery is fully charged it'll have around 8.2V and when fully depleted 6.6V (discharging beyond this point can damage the battery).


When we look into the Datasheet of the standard 5V regulator 7805 we see that the dropout voltage is typically 2V (but this can vary slightly due to manufacturing). The dropout voltage is the minimum difference required between input and output voltage for the regulator to work. While 7.2V - 5V = 2.2V is still slightly higher than required, you risk the regulator shutting off as the battery discharges more. The output voltage is also rather noisy when operating this close to the limits, so this could be an issue as well depending on what else you power with it.



What you need is a regulator with a lower dropout voltage, these are usually called "low drop out" or "LDO". There're tons of different models, with minor differences, so just look what your favorite supplier has available. Common ones are for example LM2940CT, LM2931T, L4940V5.


Another alternative would be a DC-DC step down converter like this or search ebay for some cheap chinese one. They have a much higher efficiency than linear regulators and therefore don't produce as much heat and drain the battery slower but the downside is that they're usually more expensive as well.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...