DRV8904-Q1: A couple of questions related to the body diode

Tool/software:

Hello,

My customer has been validating their system on their board using DRV8904-Q1 and I got a couple of questions.  Would you please give me your comments for these?

1. It seems they have undershoot on the OUTx pins of around -1V when they switched ON/OFF of their solenoid valve.  Is it expected?  If so, how large the Vf would be?  If I look at the datasheet, the absolute maximum voltage on the OUTx pins is -0.7V(min), so it might damage the device.  They're wondering if they need to add another external diode in parallel.  Would you please give me your comments?

2. They'd like to figure out the transient current when they switch ON/OFF of their solenoid, but it has diode on the OUTx pins and they don't know how to calculate that.  Would you please advise me how to calculate the transient current at that time?  Do you have equations for that?

Best Regards,

Yoshikazu Kawasaki