PhotoMOS AQY — 120 mA solid-state switching in a 4-SOP footprint
The AQY210KSX is a Panasonic PhotoMOS AQY series SPST-NO (1 Form A) signal relay, switching AC or DC loads up to 120 mA across a 0 V to 350 V range. It comes in a 4-SOP package (0.173", 4.40 mm body) with gull-wing leads, surface-mount termination — the same footprint as a standard SOP-4 optocoupler, so it drops into existing PCB layouts without a board spin.
On-resistance and load current — the trade-off for a 350 V blocking voltage
The 35 Ohm on-state resistance (max) is the price of the 350 V drain-to-drain blocking voltage in a small SOP package. At 120 mA load, the voltage drop across the relay is 4.2 V — that is 0.5 W dissipation, well within the SOP-4 thermal budget for a signal-level load.
Active production — no last-time-buy pressure
The base product number AQY21 covers the family; the KSX suffix denotes the 4-SOP gull-wing package on tape-and-reel.