How properly connect multiple L9963E in daisy chain

jmary · ‎2025-09-06

how to properly connect multiple L9963E in daisy chain? already tried many mode and tweak. follow the design in datasheet, for transformer isolated and capacitive, but still unable to init. for the first chip, I use SPI. init the first chip is correct, but for the upper L9963E always failed. the mcu I use SPC582B

signal seems good, but the ISO transceiver of the chip unable to read.

maybe there any member here thats already succesfully connect the daisy chain ISO

SRomeo · ‎2025-09-07

Hi jmary,
As far as I understand you are prototyping a system using SPC582B and multiple L9963E/L9963T for multi BMS communication.

If you are looking for some reference build or code, I suggest you take a look to the following L9963E ST evaluation boards, each belonging to the AutoDevKit Ecosystem:

If you need to jump-start in BMS word → 1x AEK-POW-BMSHOLD kit
If you need an all-in-one LowVoltage BMS → 1 x AEK-POW-BMSLV
build a BMS network → 1-2 AEK-COM-ISOSPI + n x AEK-POW-BMS63EN
or 1 x AEK-POW-BMSWTX / AEK-POW-BMSNOTX + n x AEK-POW-BMS63EN
build a more compact BMS network → 1 x AEK-POW-BMSCCTX + n x AEK-POW-BMSCC

This software embeds configurators and examples for Automotive building blocks, included SPC582B MCU board. Allowing you to create easily BMS chains with L9963E.

You can download it here: AutoDevKit Studio SW

Best Regards,
AEK_Team

jmary · ‎2025-09-08

Yes I already follow all those evaluation design, AEK-POW-BMSNOTXfor the L9963E base ( connect to MCU), and the upper L9963E using AEK-POW-BMS63EN. but still failed to initialize the upper L9963E. the signal in ISOHp/m and ISOLp/m is good, amplitude around 150mV but still the upper chip unable to receive. I already tried the Capacitive Isolation, its same, no working.

just, seldomly the init succed, after succed the data reading for the upper L9963E is okay. but once I power-off the chip, its will really difficult to connect again.

SRomeo · ‎2025-09-08

If your custom build is electrically equal to AEK-POW-BMSNOTX + AEK-POW-BMS63EN daisy chain configuration, then what may be wrong is the software.

I suggest you check the following AutodevKit demo project:
SPC582B - AEK_POW_BMSNOTX_SOC_Est_SingleAccess_CHAIN application for discovery

What should change from the demo application (apart from pin allocation) is just the following data field:
AEK_POW_BMS63CHAIN_node_num = 2

Please note that when a modification on a config file is done, you need to "save" and then "build" by using the Hammer icon (or else the code rerolls back to the default configuration)

Make sure your HW configuration is consistent with the suggested.

These threads related to BMS daisy chains may also help:
Solved: BMS Chain Setup Assistance - STMicroelectronics Community
Re: AEK-POW-BMS63EN Short CIrcuit on Daisy Chain - STMicroelectronics Community

Best regards,
AEK Team