I am assembling a board which uses some IRFD110 MOSFETs but I don't know which way round to insert them. The PCB shows the components with a semi-circular cutout on one end, like many components, but the component itself has no such indicator. The MOSFETs are 4-pin devices with 2 pins linked, but that is not indicated on the PCB. How do I determine which way to orientate the MOSFETs?
You can see it's datasheet and found pins detail. It's a N-Chanel mosfet if it's single in circuit. Definitely pin(S) connected to ground. You wold found GND in board.
There's no pin number assignment in the datasheet, so marked pin 1 has been arbitrarily assigned by the circuit designer. The schematic should clarify if pin 1 is at the gate or drain. It should be also quite easy to identify the shorted drain pins on the PCB.
If this is a kit, you are probably not the first person to have this problem.
Do a Google, or Google Image search for the name of the kit.
It may even turn up a picture of the board, or link to some Forum where this problem has been discussed.
Its a long shot, but luck may be on your side.
1) in a pcb layout system the packages are often designed for general use - not related to a specific device
2) there are pin numbering recommendations like IPC-7351
3) maybe the datasheet of the same device from another manufacturer shows pin numbers.
But..
Pin numbering is more a recommendation. You can not rely on it, at least not as "common knowledge". Only with a specific manufacturer and a specific device with its specific datasheet.
I looked at the datasheets from about 6 semiconductor manufacturers. Most simply copied the photo in the oldest datasheet that has no pin numbering.
I think the end with the semi-circular cutout shown on the pcb is the two drain pins connected together. The pcb probably also connects the drain pins together.
In Google I found a project posted by a student that had a pcb with two lines at the drain pins end of the IRFD110.