How can one tell if it is a lateral MOSFET

[Arroyo]

Hi I am looking for a 2sk405 and have a cross for an NTE 2393 just wanted
to make sure that the cross is a lateral mosfet as the original. Is there any
way of telling from the NTE spec sheet?

[Jay]

Laterals have low Vgs threshold and usually lower capacitance (Ci). NTE2393 has Vgs threshold of 2-4v and Ci=1600pF. No it is not lateral. The low capacitance is the preferred characteristics.

[VladimirK]

Originally Posted by Arroyo

Hi I am looking for a 2sk405 and have a cross for an NTE 2393 just wanted
to make sure that the cross is a lateral mosfet as the original. Is there any
way of telling from the NTE spec sheet?

I am almost sure, the original 2SK405 is a good quality (has low Ciss) vertical MOSFET, not lateral, since one of the very specific features of laterals - negative Id temperature coefficient, starting from 100mA, is not the case here. It shows positive tempcoeff up to 4A, that is typical for verticals.

[CBS240]

Look at the transfer characteristics in the datasheet and note at what Id the zero temperature coefficient is, that being the point where the slope of the temperature graphs of Vgs vs Id are the same. Laterals are usually around 100mA while vertical types are a few to several amps. In the case of 2SK405 that point is about 3-4 amps.

[jacco vermeulen]

Originally Posted by CBS240

Laterals are usually around 100mA while vertical types are a FEW to several amps.

For J115 it's way below 1A. (makes them an odd couple)