This part is a kind of semiconductor called AN6651.

Function of this product has MOTOR SPEED CONTROL CIRCUIT.

Manufacturers : Unisonic Technologies

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Some of the text within the PDF file :

UNISONIC TECHNOLOGIES CO., LTD AN6651 MOTOR SPEED CONTROL CIRCUIT „ DESCRIPTION LINEAR INTEGRATED CIRCUIT The UTC AN6651 is a monolithic integrated circuit designed for the rotating control of a compact DC motor which is used for a tape recorder, recorder player etc. „ FEATURES *Wide operating supply voltage: VCC=3.5V ~ 14.4V *Small four-lead plastic packer for compact motor. *Few external components *Stable low reference voltage (1.0V, typical) *Wide motor speed setting *Reverse voltage protection circuit built-in *Pb-free plating product number: AN6651L „ ORDERING INFORMATION Ordering Number Normal Lead Free Plating AN6651-T6B-K AN6651L-T6B-K Package TO-126B Packing Bulk „ PIN DESCRIPTIONS PIN NAME VCC CONTROL GND MOTOR PIN FUNCTION Supply Voltage Control signal input GND C [ ... ]

AN6651 PDF Datasheet Download