MC33771 Daisy Chain power consumption

[amansinghaljpr]

Hey , 

We have 2 AFEs connected in daisy chain configuration in our BMS system. What we have particularly noticed is that if the cells are left IDLE for long , only the cells connected to AFE 1 get into deep discharge whereas the cells on the AFE 2 performs well . 

AFE one is the very first AFE in the daisy chain and hence all the communication goes through it , and because of this issue , the AFE 1 dies and hence has no power to allow the communication of the AFE 2 cells to pass . 

We have followed all the design guidelines from NXP and tested our design enough to conclude that in every scenario it is always the AFE 1 which suffers from this issue ? 

Any ways through which we can debug this or any idea why this issue is happening ? 

Please note : Balancing is off , its just the AFEs connected to the battery pack . 

[amansinghaljpr]

Hey Jozef ! Thanks for your prompt reply. Yes me and vishal work on the same team and same design . And for the transformer, we do indeed use HM2103NLT transformer for TPL communication . 

[JozefKozon]

Hi Aman,

I have answered your colleague in the ticket and suggested some test. 

With Best Regards,

Jozef

[JozefKozon]

Hi Aman,

your colleague Vishal has created a ticket "IVPWR in normal and sleep conditions in AFE2 is high". He has provided a schematic there. Please confirm, that you work on the same design. If not please share your schematic with voltage levels and part values.

In the schematic I don't see what transformers you are using for the TPL lines. Please refer to the MC33771C datasheet for recommended transformers. Either HM2103 or HM2102 transformers are recommended.

With Best Regards,

Jozef