Texas Instruments UC3844D8G4

The product is called "UC3844D8G4" and it is an AC to DC Switching Converter Off-Line Switcher with a voltage of 17.5V and a frequency of 500kHz. It comes in a Tube package with 8-Pin SOIC.

The product has a duty cycle of 48%, a fall time of 50 ns, a frequency of 450 kHz, a maximum duty cycle of 50%, a maximum operating temperature of 70 °C, a maximum supply voltage of 30 V, a minimum operating temperature of 0 °C, a nominal input voltage of 25 V, one output, an output current of 1 A, an output voltage of 13.5 V, a rise time of 50 ns, and a switching frequency of 500 kHz. It has a flyback, boost topology and its dimensions are 1.58 mm in height, 4.9 mm in length, and 3.91 mm in width.

Yes, there are alternate parts available. One alternate part is the "UC2844D8TR" from Texas Instruments.

You can find the datasheet for the UC3844D8G4 on the Texas Instruments manufacturer page.