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Q: What is the pinout of NCE2305A?

Pin 1 = Gate, pin 2 = Source, pin 3 = Drain in SOT-23. This is confirmed against the NCE Power datasheet family. Body marking is '2305A.' Because SOT-23 pin order varies by manufacturer, re-verify before mixing vendors in production.

Q: Is NCE2305A N-channel or P-channel?

P-channel enhancement mode. It switches the positive rail (high-side) with the gate pulled low. For low-side switching, an N-channel like the NCE2302 is the better choice.

Q: What voltage can NCE2305A handle?

-12V drain-source, ±8V gate-source. The -12V rating suits 3.3V/5V rails with 2x margin. Keep gate drive inside ±8V - exceeding it damages the gate oxide permanently.

Q: Why does my load stay on when the gate is low?

Check for swapped source and drain first. With the body diode forward-conducting, current flows regardless of gate state - the load never turns off. On a P-channel, source connects to the positive rail ('S = supply rail').

Q: Can I drive it from 1.8V logic?

Not reliably at full performance. Threshold is around -0.7V, so 1.8V logic will switch it, but you land near the 60mΩ max zone instead of 29mΩ typ - and noise margin is thin. 3.3V logic drives it fully; 1.8V systems should use a level shifter.

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NCE2305A Pinout, Specifications & Common Mistakes

2026/8/18 15:01:34

NCE2305A Pinout, Specifications & Common Mistakes

The NCE2305A is a P-channel enhancement mode MOSFET from NCE Power in SOT-23, rated -12V / -4.1A with 29mΩ typ RDS(on) at VGS = -4.5V. Pinout: 1 = Gate, 2 = Source, 3 = Drain, body marking "2305A".

This page is worth reading before your first layout: SOT-23 MOSFET pinouts are not standardized across manufacturers.

The same package can put drain on pin 2 or source on pin 2 depending on the vendor — a forum case showed a BSS123 footprint shorting Vbus to ground from exactly that mistake.

NCE2305A Pin Diagram

Pin	Name	Type	Description
1	Gate (G)	Input	Controls the channel. Pull below source to turn on; VGS beyond ±8V destroys the gate oxide.
2	Source (S)	Power	Highest potential in normal operation — connects to the positive supply in a high-side switch.
3	Drain (D)	Power	Load side. Body diode anode sits here; it conducts if drain rises above source + 0.6V.

Key Specifications

Parameter	Value
Type / Package	P-Channel Enhancement Mode MOSFET, SOT-23
Drain-Source Voltage (V_DS)	-12V
Gate-Source Voltage (V_GS)	±8V
Continuous Drain Current (I_D)	-4.1A @ 25°C
Pulsed Drain Current (I_DM)	-16A
RDS(on) @ VGS = -4.5V	29mΩ typ / 45mΩ max
RDS(on) @ VGS = -2.5V	40mΩ typ / 60mΩ max
Gate Threshold (V_GS(th))	-0.7V typ
Gate Charge (Q_g)	7.8nC
Input Capacitance (C_iss)	740pF
Power Dissipation (P_D)	1.7W
Operating Temperature	-55°C to +150°C

Per the NCE Power NCE2305A datasheet: the trench structure keeps RDS(on) flat down to 2.5V gate drive — 40mΩ typ at -2.5V is why this part works directly off 3.3V logic. The 7.8nC gate charge keeps PWM switching efficient up to a few hundred kHz.

Typical Application Circuits

High-Side Load Switch (3.3V/5V Rail)

Two resistors you always need: the 100k pull-down on the gate holds the load off while the MCU boots, and a series gate resistor (1-10Ω) damps ringing in fast switching. Without the pull-down, a floating gate turns the switch on randomly — the classic "load powers up at reset" complaint.

Common Mistakes When Using NCE2305A

1. Swapping source and drain. The body diode then conducts constantly and the load never turns off. Memory aid from the forums: "S = supply rail." In a P-channel, source connects to the positive rail — always.

2. Assuming the SOT-23 pinout. Not all SOT-23 transistors share pin order — a BSS123 layout with the wrong footprint shorted Vbus to ground.

Verify pin 1-2-3 against the exact part's datasheet: NCE2305A is G/S/D, but a drop-in from another vendor may not be.

3. Exceeding the ±8V gate rating. A MOSFET on a 24V supply with the gate pulled to ground through a resistor saw nearly the full rail across VGS and burned out. On rails above ~8V, add a gate voltage divider or a zener clamp.

4. Using the -12V part on a 12V rail. The "A" version trades voltage for resistance — -12V gives 29mΩ but leaves almost no margin on a 12V bus with ringing. That's the -20V NCE2305 or AO3401A's job.

5. Driving the gate with less than 2.5V. Below threshold the channel never fully enhances: at 1.8V drive you're in the linear region, dissipating far more than the 29mΩ datasheet number suggests. 3.3V logic is fine; 1.8V logic needs a level shifter.

6. Ignoring the SOT-23 thermal budget. 1.7W max in SOT-23 needs copper: a 1cm² pad roughly doubles the current capacity versus a minimal footprint. At 2A continuous in a dense layout, the part runs hot long before it fails electrically.

Where to Buy NCE2305A

ICMASS stocks NCE2305A in SOT-23, lot-tested for RDS(on) and V_GS(th). Volume pricing typically ranges from $0.02–$0.05/unit depending on quantity and date code — contact us for a same-day quote and we'll confirm the exact NCE Power die, not a cross-referenced substitute.

Frequently Asked Questions About NCE2305A Pinout

Q1: What is the pinout of NCE2305A?

A: Pin 1 = Gate, pin 2 = Source, pin 3 = Drain in SOT-23. This is confirmed against the NCE Power datasheet family. Body marking is "2305A." Because SOT-23 pin order varies by manufacturer, re-verify before mixing vendors in production.

Q2: Is NCE2305A N-channel or P-channel?

A: P-channel enhancement mode. It switches the positive rail (high-side) with the gate pulled low. For low-side switching, an N-channel like the NCE2302 is the better choice.

Q3: What voltage can NCE2305A handle?

A: -12V drain-source, ±8V gate-source. The -12V rating suits 3.3V/5V rails with 2x margin. Keep gate drive inside ±8V — exceeding it damages the gate oxide permanently.

Q4: Why does my load stay on when the gate is low?

A: Check for swapped source and drain first. With the body diode forward-conducting, current flows regardless of gate state — the load never turns off. On a P-channel, source connects to the positive rail ("S = supply rail").

Q5: Can I drive it from 1.8V logic?

A: Not reliably at full performance. Threshold is around -0.7V, so 1.8V logic will switch it, but you land near the 60mΩ max zone instead of 29mΩ typ — and noise margin is thin. 3.3V logic drives it fully; 1.8V systems should use a level shifter.

Q6: What's the difference between NCE2305 and NCE2305A?

A: The A version trades voltage for lower RDS(on): NCE2305A is -12V with 45mΩ max; the standard NCE2305 is -20V with higher resistance. Same SOT-23 pinout (G/S/D). For 3.3V/5V rails the A version wins on efficiency; for 12V rails the 20V part is the safe choice.

Q7: How much does NCE2305A cost and is it in stock?

A: Volume pricing typically ranges from $0.02–$0.05/unit depending on quantity and date code. ICMASS stocks NCE2305A and ships same-day from Shenzhen. Contact us for a quote on your specific quantity.