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Topic: Ultra power saving and data buses. (Read 101 times) previous topic - next topic

astetyne

Hello,

I am designing one of my first PCBs and I want to achieve maximum power save as possible. There will be one MCU and the modules around it communicating with I2C, SPI and also UART. Some of the modules do not have software sleep mode so I will use power load switches to power them off completely.

BUT I have read on the forums that on I2C/SPI/UART data lines can be some current leakage and powered off module can interrupt data bus for other devices on that bus.

Is this a common problem I should worried about and use some of the complicated data lines isolators or is there a simple solution without need of using another components?

MCU: SAMD21G
Module on SPI: ArduCam mini 2MP
Module on UART: neo-m8n
(there are more modules on these buses but these are only which I will power down)

I do not have a general electronic education, I am just learning stuff from internet. Sorry if the answer for this question is obvious.

srnet

BUT I have read on the forums that on I2C/SPI/UART data lines can be some current leakage and powered off module can interrupt data bus for other devices on that bus.

Is this a common problem

Common problem.

Forget the PCB design for now, its essential to breadboard the circuit first.
No PMs please, they dont get answered.

astetyne

Thanks for the answer.

Forget the PCB design for now, its essential to breadboard the circuit first.
There are many QFN package components in the design so it would not be so easy on breadboard. PCB can be made for less than 2 euros so this is not a problem. Shipping take a long time even for components so it would be great to have the first design working and not ordering components for the second time.

Common problem.
Which basic solutions are used for this problem? Or if the isolator is the only choice, which one would you recommend?

Thanks

srnet

Realistically of course you cannot get a PCB done for 2euros, the cheapest I know of would cost maybe 15euros to have 5 PCBs made and delivered.

Your post is entitled 'Ultra power saving' so it really is a case of trying a circuit for real on a breadboard, testing the proposed circuit in this way could save interminable PCB revisions, with all the associated delays. I dont know of a design approach that would guarantee 'Ultra power saving' for your unknown circuit and range of devices.

Breadboarding QFNs is not difficult, there are general pupose breakouts available, but making do on bit of stripboard with a 'dead bug' approach is not difficult. 
No PMs please, they dont get answered.

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