Timeline for Why does the datasheet for this FET show two / three VGS(off) values?
Current License: CC BY-SA 3.0
11 events
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| Jan 23, 2016 at 19:58 | comment | added | Andy aka | @greggo why don't you raise this as a new question. I don't see the immediate connection with my answer but it was nearly a year ago! | |
| Jan 23, 2016 at 19:06 | comment | added | greggo | I'm looking at a datasheet for the N-channel 2N5457 from fairchild, the range of Vgs(off) is from -0.5V to -6.0V (and ranges to -8 for the 2N5459). The range of VGS(off) mentioned any of the charts is smaller, only up to -3.7V. If you have a common-drain circuit, with a resistor load on the source and the gate sitting at 0V, does variation in this parameter mostly affect what DC voltage you end up with on the source? | |
| Apr 10, 2015 at 7:51 | vote | accept | MrPhooky | ||
| Mar 31, 2015 at 8:20 | comment | added | Andy aka | It probably is 2 volt max so ignore the 4.5 volt curves OR contact a supplier ecause somewhere down the line there are data sheet errors. In all my many years I've never seen a data sheet from Fairchild that was this contrary lol. | |
| Mar 31, 2015 at 7:56 | comment | added | MrPhooky | OK. I don't really understand why they've done that with the datasheet... But looking at some supplier pages for them (Mouser + Farnell [Newark]) and one quotes a VGS(off) as Max of 2V and the other just says 500mV at 1.0nA drain current... | |
| Mar 30, 2015 at 21:46 | comment | added | user16324 | It's possible both devices are made using the same process therefore the same graph could be relevant to both, with the J175 to 177 parts being binned according to the actual Vgs(off) at test, and the MMBFJ271 being binned differently for whatever reason. | |
| Mar 30, 2015 at 21:13 | comment | added | Andy aka | @MrPhooky yes, VGS(off) is fixed for any device and in the two graphs in my answer they demonstrate what a 4.5 volt device does and a 2.0 volt device does when the gate-source voltage is altered. The graph on the left is for a negative drain current and the graph on the right for a positive drain current. | |
| Mar 30, 2015 at 21:09 | comment | added | MrPhooky | So (excuse the noob like question) is VGS(off) a fixed value? Like it won't change depending on other variables like currents or VDS? | |
| Mar 30, 2015 at 19:59 | history | edited | Andy aka | CC BY-SA 3.0 |
added 78 characters in body
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| Mar 30, 2015 at 18:15 | comment | added | bitsmack | Good answer! Especially "Fairchild may have dropped a major clanger" :) | |
| Mar 30, 2015 at 17:14 | history | answered | Andy aka | CC BY-SA 3.0 |