From: John Popelish
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Subject: Re: Choosing a MOSFET Driver
Date: Wed, 02 Oct 2002 15:37:16 GMT
NNTP-Posting-Date: Wed, 02 Oct 2002 11:37:16 EDT
Bill yg wrote:
> Dear All,
> How could I choose a MOSFET driver that may suit my needs? I need to
> switch a IRF830 (IRF840 also), with a MOSFET driver, within 5 us.
> Which MOSFET driver should I choose? In particular, between MC34151
> and TPS2811, which will you recommend? Is SMT driver doing a better
> job then PDIP drivers?
Your switching time of 5 us is not very fast, so you have a huge
number of choices. Is this a one off, or a design for high volume, or
something in between? Is cost very important? Is size or long term
availability and multiple sources a factor? Two pieces of info (fet
type and time) is not nearly enough information to narrow the choices
in any thoughtful way.
As a start, consider the total charge that has to be delivered in 5 us
with a full voltage swing on both gate and drain. The IRF830
specifies a maximum of 24 nC with a 400 volt drain swing and a 10 volt
gate swing. The IRF840 datasheet
specifies 63 nC. Since the second is larger, a driver that will swing
it will certainly be fast enough for the 830.
Iaverage=63 nC/5 us Iaverage=12.6 ma I would select a driver that
can deliver at least twice this at mid voltage swing in order to
expect the average current is this high.