"Chris Hibler" wrote in message
news:8e1eaa33-a91a-4a60...@n2g2000yqg.googlegroups.com...
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Nope -- an IRF540 is not a good sub for the IRL540 or 22NE10L.
The "L" parts have TTL compatible gate voltages.
A TTL gate has a minimum high level output voltage of about 2.4 volts.
To turn on any N-channel MOSFET transistor - the Gate voltage must be
sufficiently high enough as listed by the spec sheets VGS(th) voltage.
The IRL540 requires a Gate threshold voltage of 1 to 2 volts. A TTL part
exceeds this voltage so a TTL gate's high level output would guarantee the
gate would turn completely on. The IRL540 is guaranteed to have turn on and
turn off voltages that are compatible with a standard TTL device.
The IRF540 requires a Gate threshold voltage of 2 to 4 volts. A TTL gate
*might* turn this part on if the specific part being used has a threshold in
the 2 to 2.4 range. If the specific part being used has a threshold closer
to the 4 volt range then the MOSFET probably won't turn on properly or
fully. The IRF540 *might* work or it might not work. And no guarantees that
a working part would remain working if the ambient temperature in the room
changes.
Another aspect to an IRF540: An IRL540 operates more as an on-off switch but
an IRF540 does not. Depending on voltages, an IRF540 can also operate as an
on-off switch and can also operate anywhere in between on and off (half on)
depending on input voltage. If the TTL device cannot quite drive the gate
voltage high enough then the MOSFET may end up partially conducting. This
can have different results depending on how far it is turned on.
22NE10L has similar characteristics to that of the IRL540 as far as gate
threshold voltages.