# HCPL3700M optocoupler: why is pulse generator connected to both AC and DC pins?

I'm reading the datasheet for the HCPL3700M AC/DC to Logic Interface Optocoupler. In a test circuit diagram, it shows a pulse generator connected to both the AC and DC pins (see attached).

• Why would it need to go to both?
• Why is the pulse connected to the ground on the logic side? Is the purpose not to keep higher voltage AC separated from the logic side?

The datasheet can be found here: https://www.mouser.com/datasheet/2/308/HCPL3700M-1306568.pdf

Thanks!

• Why is the pulse connected to the ground on the logic side? ... the AC side is not connected to the same ground – jsotola Nov 27 '19 at 0:09