This question is not related to any particular device. Design question

Harini Madhusudhan

I am fairly new to pcb deisgn.I wanted to understand isolation for power supplies for the board I am designing. The board would have a couple of ADCs, DACs and microcontroller. It would be powered with a 24V supply which needs to stepped down to 15V,5V and 3.3V. The topology that I have is 24 to 15V isolated and the 15V to 5V and 3.3V non isolated. The 15V, 5V and 3.3V rails are for ADCs, DACs and Serializers. Should I have another 24V to 3.3V isolated power supply for the microcontroller and CAN transceiver? Or can I do another non isolated 15V to 3.3V? Any help would be useful. Thanks!

Harini

over 7 years ago

0 Chris Glaser over 7 years ago

TI__Guru**** 150870 points

Hi Harini,

I think your question is: can you power multiple devices from the same 3.3V DC/DC? Sometimes this is done. But if one device is noisy and the other sensitive, they may be kept separate.

What are the load currents that you need for each output?

0 Harini Madhusudhan over 7 years ago in reply to Chris Glaser

Prodigy 160 points

Hi Chris,

No. I wanted to understand if we absolutely need isolation or understand the factors to decide if isolation is required for power supplies powering analog (includes mixed signal) and digital devices.

Thanks!

0 Chris Glaser over 7 years ago in reply to Harini Madhusudhan

TI__Guru**** 150870 points

Thanks for clarifying. Let me loop in those responsible for isolated devices.

What type of system do you have? How is the 24V created and what is its tolerance, etc?

Power management

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This question is not related to any particular device. Design question