Understanding Pinout Diagram of Mosfet

[The13thParish]

Dear all,

I have a schematic from which I am building a circuit. There are two MOSFETS required for which I have found an equivalent part number (and datasheet) on Mouser to the one indicated on the schematic. I've posted the schematic and pinout side-by-side in the attached image.

Comparing the schematic with the pinout from the datasheet, I'm a little confused by the difference in symbol between the two. Can anyone guide me through which pins from the datasheet (D1, D1, S1, G1 for the p-channel and D2, D2, S2, G2 for the n-channel) correspond to the ones in the schematic? In particular, I am confused by the "hook" looking pin on the schematic which doesn't look like anything from the datasheet.

Any tips or pointers, even general ones, are gratefully received.

All the best,
Ryan

[Zero999]

A MOSFET only has three connections to the semiconductor junction: gate, source and drain. Quite often there will be multiple pins to the same part of the semiconductor junction, to reduce the resistance.

The IRF7105, has an N-channel and P-channel MOSFET, in the same package.

Ignore the hooks, it's just the style of symbol used in the schematic.

For the P-MOSFET, pin 1 on the IRF7105, goes to #2 on the schematic and pin 7 & 8 on the IRF7105, to #5 schematic. Now figure the rest out yourself.

[David Hess]

I do not think the hooks correspond to anything in the MOSFET structure, unlike the other side where the arrow is.  It does not seem to represent the construction of a dual gate MOSFET.

There is a fourth connection at the arrow which represents the substrate but in almost all MOSFETs it is shorted to the source as shown by the symbol.  There are 4-pin MOSFETs which make the substrate connection available separate from the source but this has nothing to do with the gate.

[The13thParish]

Pin 1 doesn't belong to the p-channel mosfet, but the n-channel one.

At any rate, am I correct to assume that the source and drain for the p and n-channel are reversed (the gates remaining the same)? I notice that many diagrams switch the positions such that the drain position for the n-channel is the source position for the p-channel and conversely. The pinout diagram for the IRF7105 however has the source and drain in the same position as labelled by the S and D pins.

All the best,
Ryan

[The13thParish]

OK, now I see that the symbol for the p-channel is often (in other places) shown vertically flipped. I think I've solved this problem. What all these shenanigans have highlighted is that I need to do more reading . . .

All the best,
Ryan

[Zero999]

Pin 1 doesn't belong to the p-channel mosfet, but the n-channel one.

You're right. I should have said N-channel MOSFET. The fact you've spotted my mistake shows you understand it.