Question Regarding a FET

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#1
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Hi All,

I am looking at a FDV304P FET. (http://download.siliconexpert.com/pdfs/2004/0615/lib/manual/fsc/ds/fdv304p.pdf)

In the schematic drawing on the datasheet, a diode exists between the Drain and the Source. So,

1) Is the diode to be treated as a normal diode, ie, current can freely flow between the Drain and the Source when Vdrain > Vsource?

2) What is the purpose of this diode?

Thank you!

-Winston

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Absorbs reverse polarity spikes from a relay coil (for example) when fet shuts off. V=L*di/dt

Imagecraft compiler user

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Thanks bobgardner,

So, the diode should be treated as a normal diode, ie, current can freely flow between the Drain and the Source when Vdrain > Vsource?

Thanks!

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The datasheet gives the details..

Quote:
DRAIN-SOURCE DIODE CHARACTERISTICS AND MAXIMUM RATINGS
Maximum Continuous Drain-Source Diode Forward Current -0.5 A
IS
Drain-Source Diode Forward Voltage -0.89 -1.2 V
VSD VGS = 0 V, IS = -0.5 A (Note)
Note:
Pulse Test: Pulse Width < 300μs, Duty Cycle < 2.0%.

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Quote:
So, the diode should be treated as a normal diode, ie, current can freely flow between the Drain and the Source when Vdrain > Vsource?
Yes. This diode is a result of the physical implementation of the MOSFET and is often referred to as the body diode.