This part is a kind of semiconductor called 57BYGH201.

Function of this product has HB Stepper Motors.

Manufacturers : KySan

Image and pinout :

Some of the text within the PDF file :

Fax Orders to 650-960-3875 HB Stepper Motors Step Angle 1.8°±5% Insulation Resistant 500V DC 100MO Min Insulation Strength 50Hz 1Minute 500V Min Ambient Temperature -20ºC~+50ºC Temperature Rise 80ºC Max Shaft Radial Play 0.02mm Max Shaft End Play 0.1-0.3mm Stepper Motor 35BYG, 39BYG Series HB Stepper Motors Kysan# 1121001 1121002 1121003 1121004 1121005 1121006 1121007 1121008 1121009 1121010 1121011 1121012 1121013 1121014 1121002 1121004 1121006 1121007 1121008 1122001 1122002 1122003 1122004 1122005 1122006 1122007 1122008 1122009 1122010 1122011 1122012 1122013 1122014 MFG# 35BYG002 35BYG005 35BYG007 35BYG008 35BYG307 35BYG305 35BYG408 35BYG202 35BYG101 35BYG201 35BYG202 35BYG205 35BYG305 35BYG310 35BYG005 35BYG008 35BYG305 35BYG408 35BYG202 39BYG101-01 39B [ ... ]

57BYGH201 PDF Datasheet Download