Isolating power for bluetooth

[seantkezm]

Hello my friends!
I am not sure if power supplies is the right section for this, but here it goes.

I am hoping to power a bluetooth board (TinySine 5v) with the same power supply as my amp board in a portable system. I would like to use an isolated DC DC converter from murata, but I am not sure which would be ideal. I did a search: Isolated DC-DC Converters | Murata Manufacturing Co.: 5.00W - 30.00W and 5.0V - 5.0V | Murata Manufacturing Co.
But I had no idea there would be that many choices and I have no idea what makes each different.

Also, if I get one that is dual output (+5/-5), what does that practically mean? ie. could one output power the BT board and one be an output to charge a phone? Or is that inherently wrong? Sorry, I'm a biologist and my electronics knowledge is pretty amateur (so far).

Thanks everyone in advance!

 

[rayma]

if I get one that is dual output (+5/-5), could one output power the BT board
and one be an output to charge a phone?

Most equipment will require a positive voltage, so I'd have two isolated positive converters
if you want to charge two things at once, unless the one you select is enough power for both.

 

[HarryY]

Be careful with some of those as they can be noisy.

Personally I prefer plain old fashioned power supplies (non- switching)

 

[Antana]

You want to use a separate DC supply for your Bluetooth, but what do you want to achieve with that? You do not explain why you want it.

 

[seantkezm]

Well, I only wanted to run one power supply wire to the speaker. I was figuring on using a leftover laptop supply. So I would need to drop the voltage from 19v (probably) to the 5v for the BT module. From what I read, an isolated dc dc converter like the muratas is a good solution.

Please tell me, if there is a better solution that does not cost a great deal more or is significantly more difficult for someone of my experience.

 

[Antana]

Please tell me, if there is a better solution that does not cost a great deal more or is significantly more difficult for someone of my experience.

Ok, that makes it more clear 🙂 I would suggest a simple DC-DC Buck converter. You can simply buy a chip and design the circuit around it. Also you can go for a more 'of the shelf' solution. A buck is recommended, since it does not disipate to much heat, however you need to do some filtering at the in- and output. You can also use a buck to go to aprox. 8V and use an LDO for the last 3V, this gives you a nice clean 5Vdc

 

[seantkezm]

Is something like this what you mean?
DC-DC 9V/12V/19V/24V to 5V 3A Converter Step Down Voltage Power Supply Module
Or maybe?
GEREE DC/DC Converter 8-22V To 5V 3A/15W Dual Female USB DC To DC Buck Converter Step Down Power Supply Module - - Amazon.com

Again, I don't know anything for sure, but I read those were supposed to be very noisy? Does an LDO (Low Dropout Regulator?) "clean" that? What is the benefit of one over just going straight to 5v?

Also, thanks!

 

[Antana]

The top one is something that could do. Its might be just sufficient and low-noise enough. Of nit, i would suggest you find one with approx. 8Vdc output en connect an LM7805 as final stepdown. You can add some extra filtering (https://www.maximintegrated.com/en/app-notes/index.mvp/id/883) if you want. LDO's are mostly more low noise, compared to a buck. Question is: does your bluetooth module not already have an LDO 😉

 

[seantkezm]

I have absolutely no idea! This is the model I was looking at.
TSA6013 - Bluetooth Audio Receiver Board(Apt-X)

Also, what about this?
L7805 LM7805 Step Down Converter 7.5V-35V to 5V Regulator Power Supply Module
That seems to have LM7805 already integrated?