"Gareth Magennis"
** Got nothing WHATSOEVER to do with LATERAL mosfets !!!These are completely different animals to switching mosfets.
Originally invented by Hitachi and sold in TO3 packs as 2SK ( N ch) and 2SJ ( P ch) numbers as the perfect output devices for audio amplifiers. Power amp makers in the UK, Australia and NZ pounced on them and for a while in the mid 1980s, MOSFET amps were the industry standard.
Later, Hitachi supplied plastic pack ( TO3P) versions too - then stopped making the TO3 devices completely in the late 1980s. There was shock, horror and nashing of teeth until it was discovered that an obscure semiconductor maker in Scotland ( of all places) was making very similar lateral devices to Hitachi ( under licence?) - this was Semelab.
Initially, all Semelab devices had SML part numbers on them, but later this changed to BUZ part numbers. The exact same devices are also sold under the Exicon brand and Magnatec. Magnatec also supply dual chip versions of the same devices - this simply doubles the max current and max power dissipation ratings.
Hitachi lateral mosfets in plastic packs are now sold under the brand " Renesas " .
A lateral mosfet will always have the source connected to the case or heatsink tab, have a threshold voltage of about 0.7 volts, come in P and N channel versions and be found in audio amplifiers and very little else.
OTOH - switching mosfets have the drain connected to the heatsink tab, are almost all N channel types ( no genuine P ch compliments exist) have threshold voltages of 2 to 5 volts and are found mostly in switching PSUs, motor drives and class D amplifiers.
.... Phil