DRV8873: question from the datasheet

Amelie,

• In PH/EN control mode, does it support speed adjustment? Or it could only have one speed.

  Speed adjustment is done by using PWM control on the "EN" pin.  "PH" pin is for direction control.  Higher duty cycle on EN pin results in higher speed.  Decrease duty cycle for lower speed.  

• In PWM, how could DRV8873 realize speed adjustment?

   Like PH/EN, you use PWM to control speed.  One input can be held in LOW or HIGH state and PWM opposite input  for speed control.

• Why SRC can't short to GND directly?

These pins SHOULD be directly connected to GND.  I am sorry if text is confusing.

• How could How to choose the appropriate SR value？

This pin is used to help slow edges to pass EMC testing.  Fast edges results in lower switching losses.  Slower edges should give you better EMC performance.  So, it is a tradeoff.  I would start with the default value of 10.8V/us.