static drain-source on resistance
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Posted by kell on July 30, 2007, 2:50 pm
Please log in for more thread options On the datasheet for the STP80PF55 http://www.st.com/stonline/books/pdf/docs/8177.pdf I can't make head or tail of figure 6. What is Vgs? It can't be 10 volts, the numbers all wrong for that. | |||||||||||||||||||||||||||||||||||||||||||
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Posted by Robert Wilson on July 30, 2007, 3:00 pm
Please log in for more thread options Well it's reasonably obvious what it is, it's the voltage required between the gate and the source to produce the specified current in the draon source connection. Have you not used one before? It's an honest question, asked with all due respect. Sincerely, Robert. kell wrote: | |||||||||||||||||||||||||||||||||||||||||||
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Posted by Spehro Pefhany on July 30, 2007, 3:06 pm
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wrote: >On the datasheet for the STP80PF55
>http://www.st.com/stonline/books/pdf/docs/8177.pdf >I can't make head or tail of figure 6. What is Vgs? It can't be 10 >volts, the numbers all wrong for that. I suggest that Vgs is probably 10V, but that graph is so screwed up you're probably better off to ask ST for a correct one. At least the Y axis is wrong in title, and probably in values by 10:1. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com | |||||||||||||||||||||||||||||||||||||||||||
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Posted by Anthony Fremont on July 30, 2007, 3:56 pm
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kell wrote: > On the datasheet for the STP80PF55
> http://www.st.com/stonline/books/pdf/docs/8177.pdf > I can't make head or tail of figure 6. What is Vgs? It can't be 10 > volts, the numbers all wrong for that. It's a pretty strange looking graph but, if I understand, the horizontal axis represents Vgs's from 2.5V thru ~7V. The vertical axis represents the amount of drain current (Id) required to create an arbitrarily chosen 5V drop (Vds). Since there is a well defined curved line, I suppose that proves that Rdson is fairly static for a given Vgs. I don't know why they felt the need to make a puzzle out of it. This looks allot like the work of "The Center of Confusion". ;-) | |||||||||||||||||||||||||||||||||||||||||||
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Posted by Spehro Pefhany on July 30, 2007, 4:03 pm
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On Mon, 30 Jul 2007 14:56:26 -0500, "Anthony Fremont" >kell wrote:
>> On the datasheet for the STP80PF55
>> http://www.st.com/stonline/books/pdf/docs/8177.pdf >> I can't make head or tail of figure 6. What is Vgs? It can't be 10 >> volts, the numbers all wrong for that. >
>It's a pretty strange looking graph but, if I understand, the horizontal >axis represents Vgs's from 2.5V thru ~7V. The vertical axis represents the >amount of drain current (Id) required to create an arbitrarily chosen 5V >drop (Vds). Since there is a well defined curved line, I suppose that >proves that Rdson is fairly static for a given Vgs. I don't know why they >felt the need to make a puzzle out of it. This looks allot like the work of >"The Center of Confusion". ;-) One hint that something is seriously wrong is that a graph called "Static drain-source on resistance" does not have ohms as the units for the dependent variable. A second hint is that if you interpret the Y axis as ohms, it's about 10:1 too high to match the typical Rds(on) figure of 16m ohms. A third hint is that Vgs is not stated. Garbage. Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com | |||||||||||||||||||||||||||||||||||||||||||
> http://www.st.com/stonline/books/pdf/docs/8177.pdf
> I can't make head or tail of figure 6. What is Vgs? It can't be 10
> volts, the numbers all wrong for that.
>