This part is a kind of semiconductor called 17N40.

Function of this product has FQP17N40.

Manufacturers : Fairchild Semiconductor

Image and pinout :

Some of the text within the PDF file :

A3977 Microstepping DMOS Driver with Translator Features and Benefits ▪ ±2.5 A, 35 V output rating ▪ Low rDS(on) outputs, 0.45 Ω source, 0.36 Ω sink typical ▪ Automatic current decay mode detection/selection ▪ 3.0 to 5.5 V logic supply voltage range ▪ Mixed, fast, and slow current decay modes ▪ Home output ▪ Synchronous rectification for low power dissipation ▪ Internal UVLO and thermal shutdown circuitry ▪ Crossover-current protection Description The A3977 is a complete microstepping motor driver, with builtin translator. It is designed to operate bipolar stepper motors in full-, half-, quarter-, and eighth-step modes, with output drive capability of 35 V and ±2.5 A. The A3977 includes a fixed off-time current regulator that has the ability to operate in slow-, fast [ ... ]

A3977 PDF Datasheet Download