top number is the inhouse marking code
bottom is the date code only "yww"
both look like they're from a small company with only 1 facility, since no factory or wafer code was included.
could be anything from this range.. LDO, mosfet or custom laser trimmed part.
alternate parts **broken link removed** High Speed Optocoupler, Single and Dual, 10 MBd https://www.fairchildsemi.com/ds/FO/FOD0721.pdf High Speed Optocouplers High CMR, 25Mbit/sec Logic Gate