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| From | Winfield Hill <hill@rowland.harvard.edu> |
|---|---|
| Newsgroups | sci.electronics.design |
| Subject | Re: ping Win, SiC fets |
| Date | 2016-11-02 17:50 -0700 |
| Organization | Rowland Institute |
| Message-ID | <nve1k80d1g@drn.newsguy.com> (permalink) |
| References | <bfok1c9ijr8oat3h7ggpr7utlmkhsnqa7b@4ax.com> <nvdpoi0319h@drn.newsguy.com> <skrk1c13nuusgtgnkdu3nru4i8g7a1pldd@4ax.com> |
John Larkin wrote...
> Winfield Hill wrote:
>> John Larkin wrote...
>>>
>>> I think you were working with high-voltage SiC fets.
>>> What sort of fall times can you get at 1kV or so?
>>
>>> I want to switch 6 or 7 kV to ground, fast, into a
>>> 50 ohm load, and need to stack fets. The higher
>>> the fet voltage, the fewer I need to stack and drive.
>>
>> Also, 7kV and 50 ohms, with 50-ohm cable, means a
>> current of 70A.
>
> Well, actually, 140 amps.
You need to source the (presumable short) 50-ohm coax
cable with a 50-ohm back-terminating resistor. That
means the switched load is 100 ohms, not 50 ohms. At
the far end of coax you see full voltage, as the pulse
arrives. The 2x reflected signal goes back to the
source resistor and stops the high current draw. But
to insure the fast risetime, you need to source the
70A current into 100 ohms, with your desired risetime.
That's bad enough!!
--
Thanks,
- Win
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ping Win, SiC fets John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-02 15:17 -0700
Re: ping Win, SiC fets Winfield Hill <hill@rowland.harvard.edu> - 2016-11-02 15:36 -0700
Re: ping Win, SiC fets John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-02 15:58 -0700
Re: ping Win, SiC fets Winfield Hill <hill@rowland.harvard.edu> - 2016-11-02 17:50 -0700
Re: ping Win, SiC fets John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-02 18:02 -0700
Re: ping Win, SiC fets Winfield Hill <hill@rowland.harvard.edu> - 2016-11-02 18:34 -0700
Re: ping Win, SiC fets TTman <pcw1.cad@ntlworld.com> - 2016-11-03 08:52 +0000
Re: ping Win, SiC fets Martin Brown <|||newspam|||@nezumi.demon.co.uk> - 2016-11-03 09:24 +0000
Re: ping Win, SiC fets Jeroen Belleman <jeroen@nospam.please> - 2016-11-03 10:25 +0100
Re: ping Win, SiC fets John S <Sophi.2@invalid.org> - 2016-11-03 07:11 -0500
Re: ping Win, SiC fets Jeroen Belleman <jeroen@nospam.please> - 2016-11-03 14:32 +0100
Re: ping Win, SiC fets Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2016-11-03 09:00 -0700
Re: ping Win, SiC fets John S <Sophi.2@invalid.org> - 2016-11-06 17:47 -0600
Re: ping Win, SiC fets Tom Gardner <spamjunk@blueyonder.co.uk> - 2016-11-03 09:29 +0000
Re: ping Win, SiC fets TTman <pcw1.cad@ntlworld.com> - 2016-11-03 11:43 +0000
Re: ping Win, SiC fets Tom Gardner <spamjunk@blueyonder.co.uk> - 2016-11-03 12:16 +0000
Re: ping Win, SiC fets upsidedown@downunder.com - 2016-11-03 18:56 +0200
Re: ping Win, SiC fets John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-03 08:59 -0700
Re: ping Win, SiC fets Winfield Hill <hill@rowland.harvard.edu> - 2016-11-03 10:40 -0700
Re: ping Win, SiC fets John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-03 11:02 -0700
Re: ping Win, SiC fets Winfield Hill <hill@rowland.harvard.edu> - 2016-11-03 11:29 -0700
Re: ping Win, SiC fets dagmargoodboat@yahoo.com - 2016-11-02 15:42 -0700
Re: ping Win, SiC fets John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-02 15:54 -0700
Re: ping Win, SiC fets dagmargoodboat@yahoo.com - 2016-11-02 17:10 -0700
Re: ping Win, SiC fets Winfield Hill <hill@rowland.harvard.edu> - 2016-11-02 17:53 -0700
Re: ping Win, SiC fets Winfield Hill <hill@rowland.harvard.edu> - 2016-11-02 17:54 -0700
Re: ping Win, SiC fets Cursitor Doom <curd@notformail.com> - 2016-11-03 15:38 +0000
triacs and electronics engineering Winfield Hill <hill@rowland.harvard.edu> - 2016-11-03 10:46 -0700
Re: triacs and electronics engineering Gunther Heiko Hagen <guntherxxx@quantserve.de> - 2016-11-03 18:01 +0000
Re: triacs and electronics engineering John Larkin <jjlarkin@highlandtechnology.com> - 2016-11-03 11:40 -0700
Re: triacs and electronics engineering Jon Elson <jmelson@wustl.edu> - 2016-11-03 13:56 -0500
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