THVD8000: multiple DC power supplies on the same PODL

Hi Mohamed,

Do you have a block diagram of what you're talking about on power line system? I want to make sure I understand the system correctly.

What is the max voltage and current your power line will draw? We need to verify if THVD8000 can drive through the peak loading of the system.

I'm also not familiar with PODL, is there anything device on the bus communicating through an AC/modulating signal?

From the THVD8000 perspective, the power supplies will sit behind an inductor and so the THVD8000's communication should be attenuated from the supply side. The THVD8000 would also sit behind capacitors which should block out the DC supplies from being seen by the THVD8000. 

-Bobby

Hello Bobby,

Thank you for your prompt response.

Below is the proposed block diagram for having multiple power supplies on the same PODL bus.
https://ibb.co/7y0bPJQ

All nodes require 12V for operation and can tolerate up to 16V. The concept is that if one power supply is insufficient to meet the power demands of all nodes, a secondary power supply will provide the additional power needed.

Do you think this approach is feasible?

BR

Hi Mohamad,

It looks like the website that you provided (uploaded the block diagram) is being blocked by the TI network. Are you able to upload the picture/file directly to the TI thread? You can do that by clicking the insert tab on the response box then click on image/video/file. If that doesn't work you can send it through an email to me (let's try the forum first though).

Mohamad OUSSAYRAN said:

All nodes require 12V for operation and can tolerate up to 16V. The concept is that if one power supply is insufficient to meet the power demands of all nodes, a secondary power supply will provide the additional power needed.

From this description, it does sound like it's possible. THVD8000 can support 16V DC, though we may want to verify the max current thats being driven on the bus.  The rule of thumb with THVD8000 is it's output impedance is about 25ohms. If you have a 16V source that supplies a peak current of 500mA then the output impedance is 32 ohms which THVD8000's output drive of 25 ohms should be able to overcome. If the current was 2A then the impedance would be 8 ohms (=16V/2A) which would mean THVD8000 wouldn't be enough to drive through that and we would need to use an additional line driver. So would you know what the max peak current being pulled would be? 

Other question is if there are other devices on this bus that are trying to communicate, I did google PODL and it seems it's used with other communication protocols. We wouldn't want other AC communication happening within the same bandwidth as the THVD8000 which may interfere with it.

-Bobby