Quote:
Originally posted by bigben2k
The Do's and Don'ts of Using MOS-Gated Transistors (PDF, 7 pages)
From that, I can see that my suggestion to reverse the Source and Drain, would actually allow the PSU voltage to get to the power bus, with a certain voltage drop, regardless of the state at the gate.
|
How so?
I suspect you are misinterpreting something.
If the source is tied to a PSU, the drain to the power bus, and the gate to ground, current into the PSU output will be less than 20uA. (Idss spec)
Ben, your design has lots of substantial flaws compared to Yo_Duh's, but turning the MOSFET around, while unorthodox, is not one of them.
Here's a hint, read ALL of this line from the MOSFET datasheet:
VGS(th) Gate Threshold Voltage 2.0 ––– 4.0 V VDS = 10V, ID = 250µA
Look at Figure 1 of the 1404 datasheet. This data is for using the MOSFET in an orthodox manner. Using it 'backwards' is likely to be 'worse'.