RF signal switching with a solid-state relay
The AQY221N2T is a Panasonic PhotoMOS™ AQY2 series solid-state relay in a 4-VSSOP package, switching AC or DC (RF) signals up to 120 mA at 0 V to 40 V. The SPST-NO (1 Form A) circuit and 12.5 Ohm max on-state resistance suit it for low-level RF path switching where a mechanical relay's contact bounce or lifetime limits are unacceptable.
Parametric fit for the BOM line
The 12.5 Ohm on-resistance at 120 mA produces a 180 mV drop, which is negligible in a 50-Ohm RF path but must be budgeted in a DC-coupled signal chain.
Obsolete — sourcing through independent channels
Panasonic lists the AQY221N2T as Obsolete. For a BOM line that requires this exact package and pinout, a board spin is the only migration path if the supply runs dry.
The 4-SMD (0.071", 1.80 mm) package with SMD (SMT) Tab termination is the 4-VSSOP footprint. The 1.80 mm body width and 0.50 mm pitch are standard for this class; the thermal pad is not exposed, so no special copper area is required under the part. Tape & Reel (TR) packaging supports automated pick-and-place.