UCC27714EVM-551: UCC28950 SYNCHRONISATION & REVERSE CURRENT

KERBILA NABIL

Part Number: UCC27714EVM-551
Other Parts Discussed in Thread: UCC28950

Hi,

We are trying to evaluate two UCC28950s under parallel synchronous rectification operation by using two UCC27714EVM-551 boards. One board is for Master and the other board is for Slav ; We would like to know why the synchronous rectification must be deactivated, or activated with the obligation to use a diode between Vout of the master and the slave ? , If it's because of reverse current ,why this should happen ?

Thank's

NABIL

over 1 year ago

0 Richard Herring over 1 year ago

TI__Mastermind 20950 points

Hello Nabil,

We have not evaluated the EVM's with the outputs in parallel so I can only give some basic advice. Usually in systems with outputs in parallel, or in multi phase systems there is some control in place to ensure there is balanced in each phase. This EVM and controller does not have this phase balance in place, which is why you are seeing the issues

Regards,

0 KERBILA NABIL over 1 year ago in reply to Richard Herring

Prodigy 60 points

Hello Richard ,

The subject of parallelization has been discussed before on TI design support, and your collegue "Colin Gillmor" advocated to use a diode rectifier and to desactivate the synchronous rectification on this case, maybe he could help ?

This is the link to the discussion :

UCC28950: Schematic check for parallel synchronous operation on UCC27714EVM-551

UCC28950: Schematic check for parallel synchronous operation on UCC27714EVM-551 - Power management forum - Power management - TI E2E support forums

Thank you for your return

Regards

0 Richard Herring over 1 year ago in reply to KERBILA NABIL

TI__Mastermind 20950 points

Hello Kerbila,

I can contact Colin on this subject, as I see that he has addressed this subject before. I expect him to confirm what I have mentioned, in that on the EVM, there is not the control in place to ensure there is balanced current in the phases in the case of a multi phase system. If this phase current balance is not in place, with synchronous rectification in place there can be large imbalance in the each phase current, negative current in one phase etc.

Regards,

0 KERBILA NABIL over 1 year ago in reply to Richard Herring

Prodigy 60 points

Hi ,

Thank you for your feedback, i will come back to you if i have more questions on this subject ;

Have a nice day.

Nabil