Driving DC motor with ADuM3223 boostrap half bridge

Hello,

We are using ADuM3223 to drive DC motor with half bridge and boostrap. The purpose is to replace an old schematic using DC/DC converter with optocouplor. 

Mosfet used are IPB027N10N3, the ADuM are managed by gpio on raspberry. We have tested 2 position: supply the motor directly with bridge, and shutdown using "shunt" method (see below)

https://drive.google.com/file/d/1KnZie2zePEjXX7Tt3urAEEpgwB8gp45I/view?usp=sharing

Ou schematic look like that and are based on the eval board of the ship :

https://drive.google.com/file/d/1FCEs7yCKfJWTaJMH8cwwVvTL9zT3FNu9/view?usp=sharing

During shutdown we oberved overvoltage and timing is very long (around 10ms) that seem strange to drive a mosfet... voltage on capture below is take between PV and COM

https://drive.google.com/file/d/1AmBrsLnHKCsEXlN9j0zEHJwhJmIcuLwO/view?usp=sharing

Our schematic using same ground for motor and output supply (VDDB/GNDB) and with GNDA not at the same potentiel but using VDDB for VDDB can be the cause ? or maybe our method to drive the mosfet with gpio ? 

regards

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