AC Input Voltage Sensing : Isolation ?

Retaw

Hi Wolfspeed Experts .

I'm interested in referance design for AC/DC Converters for an DC Fast Charging product and i come across 2 Referance design :

[1] https://www.wolfspeed.com/crd25ad12n-fmc/

[2] https://www.wolfspeed.com/crd-22ad12n/

I was comparaing the ac input voltage sensing design and couldn't help noticing the presence of an Isolated Amplifier in [2] and not in [1] :

My questions will be :

1. Why [1] doesn't use an isolated amplifier ?

2. Since adding an Isolated Amplifier will cost more, why it was implemented in [2] ?

Looking forwards for your response.

Thank you & have a nice one.

TBhatia

Hello, thank you for your message. A member of our technical team is looking into your questions and we will respond shortly.  

JHayes

Hi Retaw,

How you implement voltage sensing is determined by many factors like performance metrics or specific requirements of the intended application.

For [1], high voltage signals are routed onto the control board via wires to help with noise immunity where it is divided down using a high-impedance resistor divider referenced to a well established chassis ground. For applications that don't require isolated voltage sensing, this is a cheaper and robust solution.

[2] provides a great example of how to implement voltage sensing for applications that do require galvanic isolation - for instance, any automotive application such as an on-board charger. So while this could be more expensive, it is required by the application.

Each implementation has its inherent advantages and trade-offs, so we wanted to demonstrate multiple ways to implement a sensing solution.

Thanks,

Jonathan

TBhatia

Hi, I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.