SPI daisy chain for MC33774

[Wangjianhua]

Dear NXP,

We would please request you share a reference schematic/application note on using isolated SPI communication --- MCU to MC33771xC and MC3377xC daisy chained (multiple devices).

We are not able to find the above example in any of your application notes or data sheets.

Also, why not use SPI daisy chain and instead develop TPL protocol for MC33774?

[TomasVaverka]

Hello Wang,

There are no reference schematics/ANs available for using isoSPI communication between an MCU and BCCs in a daisy-chained configuration as we use our own TPL (Transformer Physical Layer) isolated communication interface due to its scalability and efficient communication capabilities. Its main benefits are more robust Electromagnetic Compatibility (EMC) characteristics, greater high-voltage isolation and capability to achieve longer distances.

So if more than 14 or 18 cells need to be managed, the TPL interface is recommended. We offer SPI to TPL transceivers, such as the MC33664 and the newer MC33665A to facilitate communication between TPL networks and an MCU. 

For more information about TPL and daisy chain communication, please take a closer look at our AN13281 - HVBMS daisy chain communication guide. This AN is classified as a secure file requiring an NDA:

https://www.nxp.com/products/power-management/battery-management/battery-cell-controllers/14-channel...

BRs, Tomas

[Wangjianhua]

Thank you very much for your answer. 

I am curious why the number of sampling channels for AFE cells does not exceed 20. Is cost the main consideration? Integrating more sampling channels onto one AFE chip would reduce the number of chips and daisy chain points, wouldn't that be better?