This part is a kind of semiconductor called AM2303.

Function of this product has Digital-output relative humidity & temperature sensor/module.

Manufacturers : Aosong

Image and pinout :

Some of the text within the PDF file :

Aosong(Guangzhou) Electronics Co.,Ltd --------------------------------------------------------------------------------------------------------------------Tell: +86-020-36380552, +86-020-36042809 Fax: +86-020-36380562 http://www.aosong.com Email: thomasliu198518@yahoo.com.cn sales@aosong.com Address: No.56, Renhe Road, Renhe Town, Baiyun District, Guangzhou, China Digital-output relative humidity & temperature sensor/module AM2303 Capacitive-type humidity and temperature module/sensor : Application: 1. Feature & Application * Full range temperature compensated * Relative humidity and temperature measurement * Calibrated digital signal *Outstanding long-term stability *Extra components not needed * Long transmission distance * Low power consumption *4 pins packaged and fully interchangeabl [ ... ]

AM2303 PDF Datasheet Download