fjpompeo
Joined: 29 Nov 2003
Posts: 283
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 30 Jan 2007 21:47 Power MOSFET as a switch |
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Hi,
How do I use a N channel power mosfet as a switch like we do with NPN BJTs?
I mean the configuration I know but how do I calculate gate resistor, and so on?
I'll use a CEB6030L (N-CHANNEL POWER MOSFET)very common in mother boards DC/DC converters to switch on and off a 55Wx6V halogen lamp in a special camping flash light.
Regards,
Fernando
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nguyennam
Joined: 06 Sep 2006
Posts: 459
Helped: 28
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| 31 Jan 2007 14:59 Re: Power MOSFET as a switch |
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It is absolutely easy and comfortable to use the power MOSFET as a DC switch as in your case, it must be much easier than using a BJT with the better characteristics.
You need to calculate nothing, just care of the MOSFET specs itself. In most case, you need only a resistor of about 1M to 10M ohm between G and S (you may omit this resistor), a resistor of about 100 ohm to 1M ohm (meanings that you have a very wide range of free choice of resistors but always remember that these 2 resistors also make a voltage divider and your resulted Vgs may be lower than needed level).
About the MOSFET specs, you should know about the maximum Vds, Vgs, Id, and maybe Rds ON. Of course, for n-channel type, you have to ensure that voltage at G must be more positive in respect to S to make MOSFET works.
For most of MOSFET, Vgs = 5... 10V is good enough to make MOSFET open saturately. For logic-level MOSFET, it will work at logic-level of 5V, this type of MOSFET will have the letter L as the suffix of symbol, maybe your CEB6030L is that type, please check with its datasheet.
With your simple use, you can pick out the appropriate circuit from MOSFET datasheet to use.
Goodluck
nguyennam
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