Connect with us

Drain source voltage slope of MOSFET??

Discussion in 'General Electronics Discussion' started by forever074, Jun 29, 2014.

Scroll to continue with content
  1. forever074

    forever074

    22
    0
    Mar 14, 2014
    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
    [​IMG]
    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?
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    10,586
    2,360
    Nov 17, 2011
    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, (*steve*) and KrisBlueNZ like this.
  3. forever074

    forever074

    22
    0
    Mar 14, 2014
    @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?
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    10,586
    2,360
    Nov 17, 2011
    forever074 likes this.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-