Hello Mr. Zuo,
My apologies on the slow reply. Certainly I could use two DRV8803 drivers to address 5 outputs, no problem there.
I'm more concerned as to what current will be output by the device and how it may use a feedback to toggle the output. Perhaps there is a separate system which may be used to read the current and provide the necessary PWM? Additionally, I'm not seeing any equations regarding the PWM value and the corresponding current output. Is the 1A per channel maximum simply used in proportion with the duty cycle? (I.E 50% = 500mA assuming your supply goes that high?)