NCE4009S vs NCE4012S vs NCE4015S: Side-by-Side Comparison

The one-line summary: same package, same pinout, three design stops - the 9A entry buys the lightest gate charge and the lowest price, the 12A middle is the 4-8A workhorse, and the 15A top buys the lowest R_DS(on), the biggest thermal envelope, and the event ratings.

Key Differences

The R_DS(on) ladder keeps stepping down - every die is a real upgrade

Unlike some families where the top die stops improving, this one improves at every step: 16mΩ (9A) → 12mΩ (12A) → 10mΩ (15A) max at 10V. That's a 25% cut from entry to middle and another 17% from middle to top.

The consequence: at equal current the bigger dies run meaningfully cooler. At 9A the 4009S isn't even guaranteed (its 10V row is tested at 8A); the 4012S holds 12mΩ at 10A and the 4015S holds 10mΩ.

Why does the entry die have the worst resistance? Because it's built for a different job - small die, low gate charge, low price - and R_DS(on) is what it gives up.

The 4.5V rows split the family into two logic-level classes

At 4.5V the numbers are 24mΩ (9A) / 18mΩ (12A) / 15mΩ (15A) - but the test currents tell the real story: the entry die is tested at 4A, the two bigger dies at 8A.

A part tested at 8A and 4.5V stays inside its guarantee at real current on a 5V rail; a part tested at 4A is only guaranteed for light loads. The 4012S and 4015S are genuine 5V-logic power parts; the 4009S is a 5V-logic switch for light loads.

Thresholds run 2.0V max on the entry die and 2.5V on the bigger two - all three are 5V-class parts, none of them specify below 4.5V.

Gate charge and the driver burden - the tax that reverses the buying logic

Gate charge climbs 22.9 → 30 → 60nC and C_iss climbs 964 → 1780 → 3090pF. The top die charges 2× the middle die and 2.6× the entry die per switching cycle.

The pattern: each die step trades driver burden for conduction performance and event headroom. A GPIO-driven design at tens of kHz is fine on all three; a design switching into the hundreds of kHz pays the 60nC tax every cycle and often belongs on the smaller dies.

Why does the tax matter more than the datasheet page suggests? Because it's paid continuously, at whatever frequency the board runs - while R_DS(on) only matters when current flows.

Thermal envelope - the middle and top dies are near-parity, the entry pays 1.5×

P_D runs 2W / 3W / 3.1W and R_θJA runs 62.5 / 41.7 / 40°C/W - the 4012S and 4015S sit in the same thermal class, while the entry die runs about 1.5× hotter per watt.

All three carry the same fine print (R_θJA measured t ≤ 10s on FR4) and all three use the PCB as their only heatsink. Copper is the rated operating condition for the whole family, and none of them carries its headline current on a skimpy pour.

When to Choose the NCE4009S

• Loads under ~4A sustained - where 16mΩ vs 10mΩ is a few tens of milliwatts of difference.
• Fast-switching designs - 22.9nC and 964pF are the lightest gate loads in the family; a GPIO or small driver switches this die cleanly into the hundreds of kHz.
• Cost-first boards - smallest die, fewest pennies, same package and pinout as its siblings.
• Battery-powered compact stages where the 2W envelope is never approached.

When to Choose the NCE4012S

• 5V-logic loads from 4A to 8A - the 4.5V row is guaranteed at 8A, making this the family's logic-level workhorse.
• 24V boards in the 4-8A band - 12mΩ max keeps conduction loss under 0.8W at 8A.
• A balanced default when the board doesn't know its final current - middle die, middle price, 30nC driver burden.
• Inductive loads that want a characterized avalanche rating without the top die's gate charge.

When to Choose the NCE4015S

• Loads from 8A to 12A sustained - 10mΩ max is the family's lowest; at 10A it burns 1.0W against the 4012S's 1.2W.
• Hot ambients or warm cabinets - the 3.1W envelope and 40°C/W give it the biggest thermal budget in the family.
• One-size-BOM designs - one part number covering 4A to 12A SKUs.
• Half-bridge or hard-switched stages with a real driver - 60nC is manageable with a TC4420-class driver, and trr 31ns is published.

When to Skip All Three

• Sustained current past ~12A on one part. A 150-mil SO-8 lead frame binds the whole family; step to a 5×6 leadless part or a TO-252 stage, or parallel two like-for-like dies on shared copper.
• 3.3V GPIO direct drive. None of the three specify R_DS(on) below 4.5V. Pick a 2.5V-specified part or add a gate driver.
• Unclamped automotive load dump. 40V covers 12V overshoot, but an ISO 7637-2 test-5 pulse can exceed 40V - add a TVS near the alternator.
• Rails that never exceed 30V and want maximum price pressure - the NCE 30V SOP-8 line (NCE3010S-class) is cheaper where 30V suffices.

Frequently Asked Questions

Q1: Can I swap between the three without changing the PCB?

A: Yes - same package, same pinout, different electrical promises. All three are SOP-8 with pins 1-3 Source, 4 Gate, 5-8 Drain. Check two things before the swap: your actual load current and your driver. Stepping 4009S → 4012S at 5A buys a real conduction gain; stepping to the 4015S at 3A buys a 60nC gate-load tax and nothing else.

Q2: All three are 40V - what does the current rating actually buy?

A: Die size, R_DS(on), thermal envelope, and event ratings. 16 → 12 → 10mΩ at 10V, 2 → 3 → 3.1W, 40 → 60 → 70A pulse, and the avalanche and diode characterizations only appear on the 12A and 15A dies. The sticker current is a 25°C package promise; what you're really buying is the die underneath it.

Q3: Which one works with 5V logic at real current?

A: The 4012S and 4015S - their 4.5V rows are guaranteed at 8A. The 4009S's 4.5V row is only tested at 4A, so it's a 5V-logic part for light loads. On a 5V rail driving 6A, the 4012S holds 18mΩ max and the 4015S holds 15mΩ max; the 4009S has no guarantee at that current on 4.5V.

Q4: Can a 3.3V GPIO drive any of them?

A: No - by specification, none of the three. R_DS(on) is guaranteed at 4.5V and 10V only on all three dies; threshold max runs 2.0-2.5V, so a 3.3V rail starts conduction but guarantees nothing. Forum guidance is consistent: a 3.3V rail needs a 2.5V-specified part or a gate driver.

Q5: What continuous current is realistic on a real board?

A: Roughly 3-5A, 6-9A, and 9-12A for the three parts, with good drain copper. The headline ratings (9/12/15A at 25°C) derate to 6.4/8.5/10.6A at 100°C, and the package envelopes (2/3/3.1W) bind first. Fairchild's AN-1032 documents how SO-8 continuous capability collapses without copper.

Q6: Which one replaces an AO4480 socket?

A: The 4015S is the closest match, with the 4012S a valid step-down. AO4480 is a 40V/14A legacy SO-8 part with ~11.5mΩ max at 10V. The 4015S guarantees 10mΩ max - better than the original - and the 4012S covers it where the load stays under 8A. All three share the AO4480 pinout.

Q7: Can I parallel the entry die to reach the middle die's current?

A: Not as a substitute - one 4012S wins on driver burden and footprint. Two 4009S dies in parallel reach ~8mΩ effective (better than the 4012S's 12mΩ) but cost 45.8nC of gate charge against 30nC, twice the board area, and two dies to match thermally. Parallel like-for-like dies makes sense past one part's envelope; don't parallel to replace a single larger die.

Q8: Which one survives an unclamped inductive event on a 24V rail?

A: Only the 4012S and 4015S - the 4009S publishes no avalanche rating. Both bigger dies are avalanche-characterized with an E_AS test circuit in the datasheet. For a relay or solenoid kick that slips past the flyback diode, those two have the documented margin. The 9A entry die should never run unclamped into inductive loads.