topic Re: What voltage regulators should I use for the LPC11C24? in LPC Microcontrollers

What voltage regulators should I use for the LPC11C24?

matthewfilibert — Tue, 18 Jul 2017 19:38:33 GMT

The LPC11C24 needs 3.3V and 5V (for CAN). Could anyone recommend me some stable voltage regulators to use? My input will be 12V.

One concern I have is current draw. I noticed that voltage regulators have a minimum current load requirement in order to be stable. After some research, I estimate that I should be drawing from 5-50mA for the 5V regulator (powers CAN transceiver) and around 10mA for the 3.3V regulator (powers microcontroller and a current sensor).

Re: What voltage regulators should I use for the LPC11C24?

soledad — Wed, 19 Jul 2017 18:55:13 GMT

Hi,

You can use some schematic file as reference, for example check the below link:

https://www.olimex.com/Products/ARM/NXP/LPC-P11C24/resources/LPC-P11C24_revision_A_sch.pdf

Have a great day,
Sol

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Re: What voltage regulators should I use for the LPC11C24?

juanabelaira — Thu, 20 Jul 2017 11:01:29 GMT

Usually that minimum current is fairly small, a few mA, you could have just an LED to tell the thing is powered up.

I would first guess what your maximum current is, I assume not more than 100 mA, so you can choose a linear regulator with those ratings:

Vin > 12V, Vout 3V3 or 5V, Iout >= 100mA

An additional note on power: for 12V in, 3V out you will dissipate 0,9W at 100 mA. That's relatively a lot, the smallest packages (SOT-23) may not cope with that, check the ones in DPAK, etc. Also, for your PCB, keep a decent copper area and vias to ground plane for heat sinking.

Alternatively, the cooler although pricier way is to have a switching regulator. You can get 90% efficiency but will have to design it, put more components, etc.