0
$\begingroup$

Power Block Designing noob here.

I have a beaglebone 2x XbeePro(s) and another 500mAh device connected to the board i am building a PCB Around.

I need some advice on weather to use Linear Voltage Regulation vs Switching mode regulation.

Secondly if i am using linear voltage regulation setup do I need multiple regulators for the different devices?

My plan is to use A 2S 1000mAh Battery -> Fuse -> 2x 1.5A LM1084's in parallel output feed to the beaglebone and a LM3940 for both the XBees. Or its better to have each XBee on its on LM3940 drawing power from a seperate LM1084?

Linear Regulators tend to get hot on full load, hows the performance of Switching mode regulators ?

$\endgroup$
3
$\begingroup$

A linear regulator has a major drawback: it dissipates the power it doesn't deliver. Using the well-known 7805, the output voltage is 5V, your input shall be at least 7V to allow a good regulation (2V dropout voltage), if your load requires 1A, your 7805 dissipates 1A * 2V = 2W. This makes your Linear regulator hot. The best efficiency you may expect from a 7805 is 70% (and, to the best of my knowledge, a linear regulator doesn't exceed 80%).

Switching regulators are non linear. For a switching regulator, 80% is a poor efficiency (but sometimes acceptable for very cheap designs), power efficiency is usually around 90% under full charge, and may come up to 99% when large amounts of energy are involved, with an expensive design. For little loads, efficiency may drop to 60%, due to the power consumption of the regulator itself.

So, in my opinion, you should use switching regulator, for a better power efficiency and lower heat dissipation. If you need a single voltage, try to use only one regulator: it's cheaper, and avoid the little load situation. If you want to design a low power application, you'll probably have to choose a more sophisticated design, but it's probably not the case, as you use a beaglebone, which prevents you to manage each processor power supply independently.

$\endgroup$
  • $\begingroup$ Does it make sense to use the [TPS652510](www.ti.com/lit/ds/symlink/tps652510.pdf) for my application ? or maybe a dual output switching regulator? I need the PCB Footprint to be of a bare minimum. $\endgroup$ – user2967920 Jan 7 '15 at 14:43
  • $\begingroup$ Or a LTC3633A-3 This Choice is confusing. $\endgroup$ – user2967920 Jan 7 '15 at 16:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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