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MOSFET connection circuit question

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z9u2k

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MOSFET question

Hey,

I'm a bit confused.

I have an IRF5305 P-Channel MOSFET from International Rectifier.

According to the datasheet (graph attached), at -Vds = -Vgs = 5V, I should get a drain-to-source current of at least -5A - but this is not the case.

As a test, I connected the MOSFET as follows:
- Gate -> Ground
- Source -> +5V
- Drain -> Ground, through an 0.1Ω resistor.

(yes - I know this is a bit unsafe - I have overcurrent protection in my PSU)

I'm using a 500W PC PSU, which is capable of supplying significant current at 5V, so this is not the bottleneck.

When I measure the voltage across the resistor, I get an initial reading of about 70mV, and the reading keeps climbing at a rate of about 1mV every 1.5 second - which indicates a current much lower than the current in the datasheet. Measuring the current directly yields the same result.

What am I missing?

Thanks!
 

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