Hello NXP Experts,
I want to use two MC33771C in Daisy chain for monitoring 28Cells - 14 Cell each using Capacitive Isolation. I am using S32K144 as MCU as master controller.
I am considering to connect AFE1 directly to MCU using 4-wire SPI &
connecting AFE1 to AFE2 using Capacitive Isolation using isoSPI
So my questions are
1. Will AFE1 will communicate with MCU using 4-wire SPI on
2. Can AFE1 will translate 4-wire SPI data from/to MCU to isoSPI TPL protocol & send to/from AFE2 for communication.
Here I don't want to use MC33664 between MCU & AFE1 because my 5V LDO output ground is same as BAT-, so I don't think MC33664 will add advantage from ground isolation point of view.
Will this topology work ? (The similar I had use with LTC6811 instead of MC33771C here, & LTC6811 was able to translate TPL to SPI & vice versa without using additional Transceiver between MCU & first AFE1.)
Can you please help & comment on above. Also suggest any other option also.
Regards
Avi
Thank you so much Jozef, for clarifying that MC33771C will not be single handedly abled to convert 4 wire SPI to 2 wire isoSPI / TPL & if we want to use Two MC33771C then we must need to use MC33664 for TPL conversion.
So considering MC33664 I will be using Capacitive isolation as suggested in Application diagram of Datasheet. But in my Application I dont have any separate 12V or Auxiliary battery, I have only HV battery of 86V for which I am using 2 Daisy chain BCC ICs. So MCU can communicate through MC33664 using TPL to AFE1 & AFE2. But in my application I dont have any Isolated Supply for MCU i.e. VDD_5V.
So can I connect MCU ground (i.e. MC33664 Ground pins will also connect) to BAT- ground directly or is it not possible ?
Whether it will affect Functional or EMC performance of application. The block diagram of same is attached here.
Please let me know your whether this will work or not ? Or any suggestion to use Two MC33771C & S32K144 MCU in different way ?
Thanks in Advance
Avi
Hello Avi,
please refer to the RD33771CNTREVM Block Diagram. The MCU and the MC33664 shall have the same ground, but the AFE should have the separate grounds. Especially the high voltage battery domain must be separated from the low voltage domain. In the RD33771CNTREVM the capacitive isolation is used, so you can take it as a reference.
Please download the AN12963 and please refer to the section 4.5 in there for capacitive isolation description.
You can download it from the MC33771C product page, under the secure files.
With Best Regards,
Jozef
Hello Avi,
unfortunately this is not possible with our BCCs (Battery Cell Controllers). Please refer to the block diagram in the MC33771C product page. If you want to control more, than 14 Cells, then you need more, than one node. For communication of the nodes with the MCU a TPL communication is needed and for this a TPL to SPI transceiver is needed.
In your configuration you will be able to communicate only with the first BCC, with your MCU. You will not be able to communicate with the second BCC. Please download and please check the MC33771C datasheet. You can download it from the MC33771C product page, under the Secure Files.
With Best Regards,
Jozef
