Do you mean you mistake to add the 50*3.6V voltage between C17 to ground in the MC33774 first part?
Hi @guoweisun,
To ensure complete hardware safety and prevent any potential wiring issues, we have designed a intermediate "CSU BRIDGE BOARD" to route our 50S battery pack to the RDBESS774A3EVB (featuring three MC33774A AFEs in a daisy chain).
Could you please review our attached schematics (CSUBridge_Connector.png and CSUBridge_Block Diagram.png) and verify if our pin mapping and connection strategy are correct?
Thank you for your ongoing support. First, we would like to clarify the AFE stacking order in our actual hardware setup to ensure we are aligned:
AFE1 (J1_1) is designated for the High-Voltage stage (Cells 37–50).
AFE3 (J1_3) is designated for the Low-Voltage stage (Cells 1–18).
We have attached the image which document our recent findings and the critical issue we are currently facing.
We would appreciate your explicit answers to our previous questions regarding the first incident, as well as a new issue with a new board:
[Part 1: Retrospective Questions on the First Board]
Q1: Did the initial connector swap between J1_1 and J1_3 cause catastrophic internal damage to the MC33774A ICs or related circuitry during that first event?
Q2: Is it correct to assume that the multiple balancing resistors burning out during the second (corrected) connection was a direct consequence of internal damage inside the MC33774A ICs (e.g., internal FET breakdown or gate drivers stuck in an ON-state) caused by the first incident?
Q3: If we replace the damaged MC33774A ICs and all the burned balancing resistors, can the RDBESS774A3EVB board be restored to a fully functional and safe working condition? Are there any other critical companion components (such as ESD/Zener protection diodes or isolation circuit elements) that we should inspect or replace alongside the main ICs?
[Part 2: NEW ISSUE with a New Board]
Following the correct stacking order mentioned above (High-Voltage to AFE1/J1_1, Low-Voltage to AFE3/J1_3), we attempted to test our system using a completely new RDBESS774A3EVB board.
However, as soon as it was connected, smoke occurred immediately, and the balancing IC (MC33774A) on the High-Voltage segment (Cells 37–50 / AFE1) was damaged once again.
Given that the connection was mapped exactly as intended (High-to-High, Low-to-Low), could you please help us analyze why the new board failed instantly at the AFE1 stage?
Hi @guoweisun,
We did not connect the entire 50-cell pack into a single connector. Instead, our 50-cell system is divided into three separate segments with three distinct cell connectors.
