This part is a kind of semiconductor called TS19371.
Function of this product has Boost (Step-up) WLED Driver.
Manufacturers : Taiwan Semiconductor Company
Image and pinout :
Some of the text within the PDF file :
Boost (Step-up) WLED Driver with OVP SOT-26 Pin Definition: 1. SW 6. Input 2. Ground 5. OVP 3. Feedback 4. CTRL TS19371 General Description The TS19371 is a step-up DC/DC converter specifically designed to drive white LEDs with a constant current. The device can drive up to 126 LEDs (9S14P) from a 12V supply. The output capacitor can be as small as 4.7µF, saving space versus alternative solutions. A low 95mV feedback voltage minimizes power loss for better efficiency. Additional feature include over output voltage limiting when LEDs are disconnected. The TS19371 switches at a fixed frequency of 1.2MHz, allowing the use of tiny, low profile inductors and capacitors to minimize footprint and cost in space consideration applications for cellular phone backlighting or o [ ... ]