This part is a kind of semiconductor called HT7550.

Function of this product has High Driver Regulator.

Manufacturers : Holtek Semiconductor Inc

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Some of the text within the PDF file :

High Driver Regulator Features · · · HT75XX Low power consumption Low voltage drop Low temperature coefficient · · · High input voltage (up to 24V) High output current : 100mA (Pd £ 250mW) TO-92 and SOT-89 package Applications · · Battery-powered equipment Communication equipment · Audio/Video equipment General Description The HT75XX series is a set of three-terminal high current low voltage regulator implemented in CMOS technology. They can deliver 100mA output current and allow an input voltage as high as 24V. They are available with several fixed output voltages ranging from 3.0V to 8V. CMOS technology ensures low voltage drop and low quiescent current. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtai [ ... ]

HT7550 PDF Datasheet Download