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Drain source voltage slope of MOSFET??

forever074

Mar 14, 2014
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1. I often see parameter "Drain source voltage slope" in datasheet of MOSFET.
EG: in datasheet of mosfet SPW35N60CFD, Drain source voltage slope dv/dt=80V/ns
0

So what does Drain source voltage slope mean? Is that the maximum dv/dt rating?
2. When we select R_gate to driver MOSFET, what is minimum of R_gate?
How R_gate related to Drain source voltage slope?
 

Harald Kapp

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Nov 17, 2011
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Is that the maximum dv/dt rating?
Yes ist is. If the voltage rises faster, the transistor may turn on due to curent flowing into the drain-gate capacitace. Turning on the transistor when it is supposed to be off can damage the transistor and the circuit.

The minimum Rgate = 0 Ohm. What value is suitable for the circuit depends on the circuit and its parameters.
Obviously, if Rgate is large, the charge current through Cdg due to dVds/dt will chareg the gate more easily and therefore turn on the transistor at lower dV/dt. If Rgate is small, it will drain part of the charge current through Cdg and the transistor is kept of at higher dV/dt (but not higher than the max. value stated in the datasheet).

Here are some MOSFET parameters explained.
 

forever074

Mar 14, 2014
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@Harald Kapp . When we driver MOSFET with a Rgate at high frequency( Eg 100kHz), In my opinion I think The less Rgate is the less switching loss is. So why we dont select Rgate=0OHM. What does we select Rgate depending on?
 
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