Inquiring about STD4NK100Z Thermal Unstabe state in Linear mode(Saturation)

[Smug1]

Hello

We use STD4NK100Z to operate in saturation mode using Source

Follower structure.

VG.MAX =15V (Zener Clamping)

VGS = 0 to 5 V

VDS = 1000 V

Source Resistor = 4.7k

IDS = Max 3mA (4.7k ohm resistance limits)

I have a few inquiries regarding this, so I specified it below. Thank you for your answer.

(1) Regarding the Super-Junction Type, I heard that there is a Local Heat Hotspot issue for the Linear Mode(Saturation) continuous operation. but The STD4NK100Z we use is a Planar Type, I know that there are very few Local Heat Hotspot issues compared to the Super-Junction. Is it correct?

(2) Even in the Hot-SOA area considering Thermal Unstable, if it is within the SOA area, there will be no problem with operation, right?

(3) Is there any document or link to refer to the difference in characteristics between Planar Type and Super-Junction Type? Please share it with us.

[Peter BENSCH]

Welcome, @Smug1​, to the community!

your question is very similar to this one.

To answer your questions

1. The STD4NK100Z is not made with planar technology, but is a super-junction MDmesh one. So the answer here is: no.
2. This is not right, as there will be a problem.
3. Not applicable, see answer 1.

Does it answer your question?

Regards

/Peter

[Smug1]

Thank you for your quick reply.

I don't understand the question, so I'd like to ask you an additional question and thank you for your response.

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1.I was introduced STD4NK100Z is a Super-Mesh (Standard) type and is not a Super-Junction type. Did I get it wrong?

And I know that Super-Mesh Type is not a Super-Junction Type.

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2. I have a question regarding the following answer.

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It is operating as shown in Answer 3, I understand that the source voltage follows the gate voltage and the source current is determined by the source voltage and resistance and that this current flows to the MOSFET drain-source Is it correct?

so Maximum source voltage is applied up to 11V. In this regard, we have confirmed that 3mA current flows to a maximum, not 125mA, so if 3mA flows to a maximum, is there any problem with operation? (By Thermal Hotspot, not Breakdown)

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Circuit condition

Gate Voltgae Range : 5V ~ 15V

Source Voltage Ragne : 1V ~ 11V

Even if the gate voltage fluctuates, the VGS is uniform at about 4V (Source Follow)

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Gate Voltage 15V 

Source Voltage = 15V- Vth : 11V

Source Current = 11V/4700:2.34mA = MOSFET Drain-Source Current

MOSFET VDS : 989V​

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Gate Voltage 5V

Source Voltage = 5V - Vth : 1V

Source Current = 1V/4700:0.02mA = MOSFET Drain-Source Current

MOSFET VDS : 999V

[Peter BENSCH]

1. Wrong, SuperMESH is the 5th generation of superjunction technology, MDMesh the latest one. Both are different from planar technology.
2. Theoretically, it could work that way, but only theoretically. It depends on the fact that VGS(th) with 3V to 4.5V has a quite large tolerance range. Additionally it is also temperature-dependent, which is not specified in the data sheet because it is irrelevant for switching applications.

[edit] even if the following statement is correct, it does not apply here because it is not a Super Junction MOSFET:[/edit]

There is no point in looking further at the linear operation of superjunction MOSFETs as they are not suitable for such kind of applications.

If the problem is resolved or answered, please mark this thread as answered by selecting Select as best. This will help other users find that answer faster.

Regards

/Peter

[Peter BENSCH]

It is possible that I was mistaken in my statement. I am in the process of double-checking and will get back to you after a close examination.

Regards

/Peter

[Peter BENSCH]

I am very sorry for the confusion, but my statement was not correct. After consultation, I can inform: SuperMESH is planar, and since STD4NK100Z is made with SuperMESH, it follows that STD4NK100Z is suitable for linear operation.

I have already crossed out my incorrect statements above.

Regards

/Peter