This part is a kind of semiconductor called JM20339.

Function of this product has Hi Speed USB to SATA Bridge.

Manufacturers : JMicron Technology

Image and pinout :

Some of the text within the PDF file :

JMicron/JM20339 JM20339 Hi-Speed USB to SATA Bridge Description The JM20339 is single chip solution to bridge between USB 2.0 host and SATA device. The highly integrated USB 2.0 and SATA Phys technology provides a cost-effective solution to apply USB to SATA device enclosure. The USB adheres to the Mass Storage Class Bulk-Only Transport Specification. The embedded command parser supports both ATA and ATAPI command set with LBA48 bit addressing capability. Features • Compliance with Gen1i, and Gen1m of Serial ATA II Electrical Specification 1.0 • Support SATA spread-spectrum transmitter • Support SATA II Asynchronous Signal Recovery (Hot Plug) feature • Compliance with USB 2.0 (Hi-Speed USB) electrical specification • Compliance with USB Mass Storage Class B [ ... ]

JM20339 PDF Datasheet Download