AO3400A 30 V N-Channel MOSFET: Specs and Design Notes
2026-10-21 · PartVane Electronics
The AO3400A is a 30 V N-channel trench MOSFET from Alpha & Omega Semiconductor in a SOT-23 package. The datasheet (Rev 3.1, July 2023) positions it for load switches and PWM applications. This guide lists the datasheet figures that matter when you pick it for a low-voltage switch.
Key ratings from the datasheet
| Item | AO3400A |
|---|---|
| Drain-source voltage (VDS) | 30 V |
| Gate-source voltage (VGS) | ±12 V max |
| Continuous drain current | 5.7 A at 25°C ambient; 4.7 A at 70°C |
| Pulsed drain current | 30 A |
| RDS(ON) | < 26.5 mΩ at 10 V; < 32 mΩ at 4.5 V; < 48 mΩ at 2.5 V |
| Gate threshold (VGS(th)) | 0.65 V min, 1.05 V typ, 1.45 V max |
| Power dissipation | 1.4 W at 25°C; 0.9 W at 70°C |
| Junction temperature | -55 to 150°C |
| Package | SOT-23 |
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Using it with 3.3 V logic
- RDS(ON) is specified down to 2.5 V gate drive, so a 3.3 V GPIO can drive it directly in many load-switch designs.
- The gate rating is only ±12 V. Do not drive the gate from a 24 V rail without a clamp or divider.
- Thermal limits are tight in SOT-23: junction-to-ambient is 100 °C/W typical (125 max) in steady state, so check dissipation at your real current and copper area.
Check before you design in
Confirm the pinout (gate, source, drain) on the datasheet for your footprint, and verify the exact manufacturer part marking when sourcing. If you need a logic-level small-signal part for I2C level shifting instead, look at the BSS138; it is a different class of device and not a substitute for a 5 A load switch.
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Sources
Parts in This Article
- AO3400A datasheet, pinout & specs – Alpha & Omega Semiconductor
- BSS138 datasheet, pinout & specs – onsemi