ULQ2003A-Q1: ULQ2003A-Q1 Use question

Hi User, 

Thanks for reaching out on E2E! The COM pin is important when using low side switches, such as the ULQ2003A-Q1, to power inductive loads. When the low side switch is disconnected from GND, the current through the inductive load is instantly disconnected, causing the voltage to spike (V = -L * dI/dt)

Connecting the COM pin enables the flyback diode whenever this switching condition occurs. Once the voltage starts increasing, the diode becomes forward biased and gives the current a path to flow. 

Thanks,

Arthur Huang