DRV8718-Q1: output frequency spread spectrum

Hi Expert,

My customer meet the RE failure during EMI test. Their fsw to control the motor is about 20KHZ. They also have other devices which generate the 20KHZ control signa to motor drive. In order to improve the RE performance, they would like to check if DRV8718's output fsw can support 18KHZ~22KHZ spread spectrum. If yes, I think the spread spectrum need to be generated by PWM input side, correct? 

Thanks!

Ethan