This part is a kind of semiconductor called AQY221R2S.

Function of this product has RF PhotoMOS Relays.

Manufacturers : Panasonic

Image and pinout :

Some of the text within the PDF file :

RF PhotoMOS (AQY221❍2S) Lower output capacitance (C type) and RF PhotoMOSon resistance (R type). (C✕R10) High speed switching. (C type:Turn on (AQY221❍2S)time: 0.03ms, Turn off time: 0.03ms). 4.3 .169 4.4 .173 2.1 .083 1 2 4.3 .169 4.4 .173 2.1 .083 mm inch 4 3 FEATURES 1. Two option package available. R type offers greatly reduced onresistance. C type offers lower output capacitance. AQY221R2S AQY221N2S (R type) (C type) Output capacitance: C 13pF 1pF On resistance: R 0.8Ω 9.5Ω 2. High speed switching Turn on time: 30µs (AQY221N2S) Turn off time: 30µs (AQY221N2S) 3. Super miniature design SOP 4-pin type. 4. Low-level off state leakage current of 10pA The SSR has an off state leakage current of several milliamperes, where as this PhotoMOS [ ... ]

AQY221R2S PDF Datasheet Download