Hi Sato-san,
Thank you for the scope captures.
Is there a capacitor across the motor terminal? Is this causing the current spike?
[quote user="Hiroshi Sato"]The customer want to know how to use DRV8871 with 5A/1us startup current.[/quote]
The device is designed to operate with a 5A/1us startup current. The 5A/1us startup is ignored during the 2us blanking time.
In the scope captures labeled abnormal operation, the 1.64A current limit is causing the device to enter current regulation. The DRV8871 is operated as designed.
In the scope captures labeled forward1/2 and reverse1/2 with a 15kOhm resistor, the current does not stop because the current is less than the chopping current.
After the 2us blanking time, the current will stop only if:
1) There is an overcurrent event (current > 3.6A) or
2) There is an overtemperature event
3) The current is being regulated by the device.
Has the customer tried the recommended 23kOhm resistor?