2N7002

What's the P-channel equivalent? Is there one? Need jellybean high-side switch

It's my default low-power MOSFET. My Philips datasheet is from

For use at medium currents I stock AO3400 (N) and AO3401 (P). I normally choose my general-purpose stock parts after carefully considering numerous alternatives but not in the case of these two types. I bought them because they're cheap and have ratings in the appropriate range and low Rds(on). The gate charge and capacitances aren't bad but nothing special. They are available at AliExpress for less than 1.5 US cents each in small quantities with free shipping. They have served me well.

I use the BSS84.

Our standard for peak current is whatever it can do. The graphs on my Fairchild data sheet cut off at 2 amps.

Den torsdag den 1. februar 2018 kl. 17.38.37 UTC+1 skrev John Larkin:

Idea for using P fets for load switching a USB charger; if USB power is connected to the charging circuit while the load is switched on it shuts down the load by flipping the flop and locks out the ON switch:

Nice to hear it. I stocked up with several hundred of these many years ago and still have most of them. They *are* very useful as you say.

The left input comes from e.g. the MCP73833's "PWR_GOOD" line

The 1A or so capability of the BSS84 and 2N7002 are peak ratings. For continuous loads as for charging, FETs with higher ratings and lower Rds would be more suitable. Like the AO3401 I mentioned earlier or something similar.

The AO3401 is 30V, 4A and

The input needs to be pulled down in any case, so if the trigger voltage is higher than the supply there will have to be a divider there of some value. The diode is probably just paranoia if it's being fed from a logic output rather than directly from the USB supply

Well, that's why there's nothing newer then, isn't it?

Shut up! You know that they read this group and discontinue the parts when you say things like that.

Indeed, It sure seems that way doesn't it :-( ...Jim Thompson

Easy to find nothing when you don't look.

Jellybeans for discrete logic? Try some RUM:

Fraction of the capacitance. Lower voltage, obviously, that's how you get the higher performance.

It seems RF MOSFETs are completely kaput and no one cares. There are a few dual gates still remaining, with better specs. If you don't mind that. I suppose if you randomly needed a discrete NAND gate that could be handy.

BJTs are altogether better (and the other RF transistor types), so many of them survive. Except the PNPs, it seems...

Tim

Yeah! At least in the US, as soon as I design something into a board, it either goes end of life, or you just can't get the parts from any distributor. A major pain.

Jon

Hmm not just the US, reordering susumu 0.1% R's. obsolete, I find a new 0805 part number. 1/2 the power rating, now I've got to think/review... grumble.

George H.