This part is a kind of semiconductor called THB7128-E.

Function of this product has PWM current control stepping motor driver.

Manufacturers : ETC

Image and pinout :

Some of the text within the PDF file :

Ver1.3 Preliminary Specifications Product Name THB7128-E 1．Case Outline：19 pins (See attached case outline dimensions.) 2．Function ：PWM current control stepping motor driver 3．Application ：Industrial equipment etc. 4．Features： ・Output on-resistance (High side 0.3 Ω, Low side 0.25 Ω, Total 0.55 Ω; Ta = 25℃, IO = 2.5A) ・VMmax=40V(DC)，Iopmax=3.3A ・2, 1-2, W1-2, 2W1-2, 4W1-2, 8W1-2, 16W1-2, 32W1-2 phase excitation are selectable ・With built-in automatic half current maintenance energizing function ・Over current protection circuit ・Thermal shutdown circuit ・Input pull down resistance ・With reset pin and enable pin 5．Absolute Maximum Ratings／Tc=25℃ Parameter Symbol Conditions Ratings 40 3.3 6 3 -30 to +105 -40 to +125 Unit V A V V ℃ ℃ supp [ ... ]

THB7128-E PDF Datasheet Download