BQ76952: How to cascade 2 BQ76952 chips with high side NFETs to have more than 16 series cell connection

Hi,

This technical article goes into some detail on how to stack 2 BQ76952 devices: https://e2e.ti.com/blogs_/b/powerhouse/posts/how-to-stack-battery-monitors-for-high-cell-count-industrial-applications

It is very challenging to use high-side FETs in a stacked configuration, so our recommendation is to use low-side FETs in this case. There is a very good document on driving low-side FETs with the BQ76952 here: https://www.ti.com/lit/an/sluaa84/sluaa84.pdf

When using high-side FETs, the FET gates need to be turned on with the charge pump voltage of the upper device. However, when the DSG FET is disabled, the gate voltage must fall to GND (when a charger is not attached) - this would be a large negative voltage relative to the VSS pin of the upper device and would violate the abs max parameters. So additional circuitry would need to be added to prevent damage and coordinate the FET switching from both devices.

Best regards,

Matt