NCE40H12K — 40V/120A N-Channel Power MOSFET (TO-252-2L)

What Are the Technical Specifications of NCE40H12K?

Note what is identical to the 30V part: 120A, 1.25°C/W, 120W, and the same ±20V gate window. The two parts are the same thermal and current class. Only the voltage rating and the resistance rows moved.

And the resistance rows moved in a direction that surprises people. Line up the four numbers:

Read the top two rows and the 30V part wins by a tenth of a milliohm. Read the bottom two and the 40V part wins by half a milliohm. Only the bottom two are promises.

Why does that ordering exist at all? Because voltage class is not what sets resistance here — die generation is, and this die is newer than the 30V one it shares a footprint with.

When Should You Use (and NOT Use) the NCE40H12K?

✅ Use NCE40H12K when:

• Your rail is 24V. A 24V rail sits exactly at 80% of a 30V rating — the conventional derating limit — with nothing left for switching-node overshoot. The 40V part puts the same rail at 60%.
• You design against guaranteed limits. 4.0mΩ max at 10V is the best number in this TO-252 family at the 120A class, and it is the row a worst-case loss calculation is supposed to use.
• Your gate drive is 4.5V or 5V. The 4.5V row publishes 7.0mΩ max at a 10A test current. The 30H12K has no such row at all.
• You're swapping up from the 30H12K. Same footprint, same 1G/2D/3S pinout, same drain tab, same thermal resistance — the change is a reflow.
• Your gate loop is long or your driver is weak. Reverse transfer capacitance is 380pF, the lowest of the three 120A-class parts here — against 456pF on the 30H12K and 563pF on the 30H15K. Less C_rss means less Miller coupling into a slow gate.

❌ Don't use NCE40H12K when:

• You need the lowest resistance at 4.5V. The 30V NCE30H15K publishes 5.0mΩ max at the same 4.5V and 10A condition — 2mΩ better. If your driver is 5V, that part wins.
• Your load is inductive and unclamped. E_AS is 1080mJ here against the 30H15K's 1700mJ. Ruggedness is where the 30V family spends its advantage.
• Your rail is 12V or lower. A 40V rating buys margin you cannot use, on a die whose 25°C typical is a hair worse than the 30V part's.
• You want 120A continuous on a normal board. The 85A row assumes a 100°C case, which means removing 60W through copper. Tens of amps is the realistic band.
• Your rail is above 40V. This is the top of the family; the next step is a different device class, not a different suffix.

What Are the Alternatives to NCE40H12K?

So when is the voltage step the right call? Whenever the rail is 24V and the load is not inductive — and the answer is not close.

But how much room is actually left above a 24V rail?

An engineering write-up of a 24V LLC design measured switch-node ringing reaching 36V at the drain. A 30V part is already outside its rating at that point.

The conventional rule keeps the measured peak under 80% of the rating. That caps a 30V device at 24V — the rail itself, before any transient arrives.

Both bars are the same die class, the same package and the same thermal path. The only difference is how much room is left above the rail — 6V on the 30V part, 16V on the 40V part.

Half the family publishes a 4.5V row and half does not, and the ranking at 4.5V is not the ranking at 10V. The 30V part is 2mΩ better exactly where a 5V driver operates.

What Are the Typical Applications of NCE40H12K?

24V rail switching. This is the application the part exists for. A 24V rail lands on 60% of the rating, leaving room for the overshoot that hard-switched nodes produce on real layouts.

Battery packs at 6 or 7 series cells. A fully charged 7-cell pack sits near 29V, which is already past the 80% line for a 30V device and inside it for a 40V one.

Motor phases in 24V drives. E-bike controllers and small BLDC stages see the rail plus commutation spikes. The 380pF reverse transfer capacitance keeps Miller coupling low for a slow or long gate loop.

Load switching with a 5V gate driver. The 4.5V row is published at 7.0mΩ max, so a 5V rail is a characterized operating point rather than a guess.

Why Buy NCE40H12K from ICMASS?

We sample-test NCE40H12K lots at both published rows: 4.0mΩ maximum at 10V / 20A and 7.0mΩ maximum at 4.5V / 10A. Two rows means two things to measure against, and both appear in the same sheet.

This part number also carries a clone line. VBsemi lists a NCE40H12K-VB in TO-252, and third-party cross-reference tables recycle rounded figures that do not match either row. When a listing disagrees with the PDF, the PDF with the revision number wins.

We hold the whole TO-252 ladder — 30H10K, 30H12K, 30H15K and 40H12K — with the official sheet for each. Recommending the 40V part for a 24V rail, and the 30V 15K for a 5V-driven inductive load, is the same conversation when all four are on the shelf.

Orders ship same day from Shenzhen, with volume pricing that keeps a genuine 40V TO-252 competitive against clone stock wearing the same code.

Frequently Asked Questions About NCE40H12K

Q1: Is a 30V MOSFET enough for a 24V rail?

A: On paper, and only on paper. The common derating rule keeps the measured peak below 80% of the rating, and 24V is exactly 80% of 30V — so the rail alone consumes the entire margin. Any switching-node overshoot goes past it. One published 24V LLC design measured 36V of ringing at the switch node.

Q2: Why does the 40V part have a lower maximum resistance than the 30V one?

A: Because the two dice are from different generations, not from the same design at two voltages. Both are 120A parts with a 1.25°C/W thermal path and a ±20V gate window, but the 40V device guarantees 4.0mΩ max at 10V against the 30V part's 4.5mΩ. Voltage class is not the axis this family sorts on.

Q3: Should I design to the typical value or the maximum?

A: The maximum, and then adjust it for temperature. Typical values describe a median unit, not the one on your board, and conduction loss scales with the resistance you actually get. On this pair the typical figures are 3.5mΩ and 3.6mΩ — a ranking that reverses the moment you use the guaranteed rows instead.

Q4: Can I drive the gate with 5V?

A: Yes — a 4.5V row is published. 7.0mΩ max and 5.8mΩ typical, both at a 10A test current. Note that the 30V NCE30H15K publishes 5.0mΩ at the same condition, so if your driver is 5V the 30V part is the better choice, not the compromise.

Q5: What is the avalanche rating and at what test condition?

A: 1080mJ at I_AS = 46.5A, L = 1mH, from a 25°C junction. That sits between the 30H12K's 350mJ and the 30H15K's 1700mJ. Avalanche capability falls as avalanche current rises, so the current and inductance matter as much as the energy figure.

Q6: How much current can it carry continuously in a real design?

A: Tens of amps. The 85A row assumes a 100°C case, so the board is already shedding about 60W. Run the self-heating equation on a 40°C/W board and the realistic figure is near 19A at a 125°C junction. Treat the printed current as a die limit and the copper as the real constraint.

Q7: Is the 40H12K a drop-in replacement for the 30H12K?

A: Electrically yes, mechanically yes, and you gain margin on both. Same TO-252-2L outline, same 1G/2D/3S pinout, same drain tab, same 1.25°C/W. The higher rating changes nothing about the footprint, the gate drive requirement or the thermal path.

Q8: Why does the switching table quote R_L = 1Ω?

A: Because switching times are a function of the test load, not just the die. This sheet uses R_L = 1Ω and I_D = 2A; the 30H12K's row uses R_L = 0.75Ω and the 30H15K's uses R_L = 15Ω. Compare the gate charge instead, at matched gate-drive voltage, or measure on your own board.

Q9: Is there a clone of this part number?

A: Yes — VBsemi lists a NCE40H12K-VB. Cross-reference databases also recycle rounded or third-party figures for all four parts in this family, and those numbers do not always agree with the official sheets. Verify against the PDF revision, not the listing.

Q10: What is the 380pF reverse transfer capacitance worth?

A: Less Miller coupling into a slow or long gate loop. C_rss is the capacitance that feeds drain dv/dt back into the gate. At 380pF this part is the lowest of the three 120A-class parts here — the 30H12K is 456pF and the 30H15K is 563pF. Combined with 17nC of gate-drain charge, it sets how much of the drain edge lands on your gate resistor.