PhotoMOS relay for AC/DC signal switching
The AQY210KSZ is a Panasonic PhotoMOS™ AQY series solid-state relay, SPST-NO (1 Form A), rated for 120 mA continuous load current across a 0 V to 350 V AC or DC load range. It switches with a 1.13 VDC input, and the 35 Ohm max on-state resistance means the voltage drop across the relay at 120 mA is about 4.2 V — fine for signal-level loads but not for power delivery. The 4-SOP package with Gull Wing leads is a standard surface-mount footprint for signal relays, so it fits into automated pick-and-place assembly without special handling.
What the ratings mean for your BOM
The 120 mA load current is the continuous DC or AC RMS limit — this part is sized for signal switching (telecom, instrumentation, sensor outputs), not for driving solenoids or motors. The 350 V load voltage ceiling covers 240 VAC mains-derived signals with margin, or 48 V telecom rails comfortably. On-state resistance of 35 Ohms is typical for a PhotoMOS in this voltage class — it limits the part to low-current signal paths where the voltage drop is acceptable.