UM6K33NTN vs AOSS32338C: Component Comparison for Power Electronics Designers
Quick verdict
For low-current switching and signal-level applications where ultra-low gate drive voltage and dual MOSFETs in a compact package are needed, the Rohm UM6K33NTN is the better choice. In contrast, for power switching requiring higher continuous current (up to 4A), lower R_DS(on), and higher power dissipation, the Alpha & Omega AOSS32338C clearly outperforms despite a higher gate drive voltage requirement and a single MOSFET per package.
Spec comparison table
| Spec | UM6K33NTN | AOSS32338C | Notes |
|---|---|---|---|
| Configuration | Dual N-Channel | Single N-Channel | UM6K33NTN provides two MOSFETs in one package, useful for half-bridge or dual switch designs. |
| Continuous Drain Current @ 25°C | 0.2 A | 4 A | AOSS32338C supports 20× higher current, enabling power-level switching versus signal-level. |
| Drain-Source Voltage Max | 50 V | 30 V | UM6K33NTN supports higher voltage, suitable for higher voltage rails or transient margins. |
| Gate Drive Voltage (Logic Level) | 1.2 V | - (2.5 V min for R_DS(on) spec) | UM6K33NTN supports very low gate voltages, good for low-voltage logic; AOSS32338C needs higher gate drive voltage. |
| Gate Charge (Q_g) | Not specified | 16 nC @ 10 V | AOSS32338C’s gate charge is moderate; UM6K33NTN data unavailable, but logic-level gate implies low charge. |
| Input Capacitance (C_iss) | 25 pF @ 10 V | 340 pF @ 15 V | UM6K33NTN has much lower input capacitance, reducing gate drive losses and speeding switching. |
| Mounting Type | Surface Mount (UMT6 package) | Surface Mount (SOT-23-3) | Both are surface mount but different packages; affects footprint and thermal conduction. |
| Operating Temperature Range | Up to 150°C (TJ) | -55°C to 150°C (TJ) | AOSS32338C supports wider temperature range including cold environments. |
| Package | 6-TSSOP / SC-88 / SOT-363 | SOT-23-3 | UM6K33NTN is a dual MOSFET array in a 6-pin package; AOSS32338C is a single MOSFET in 3-pin package. |
| Power Dissipation Max | 120 mW | 1.3 W (Ta) | AOSS32338C can dissipate over 10× more power, critical for power switching applications. |
| R_DS(on) Max @ I_D, V_GS | 2.2 Ω @ 0.2 A, 4.5 V | 50 mΩ @ 4 A, 10 V | AOSS32338C has dramatically lower R_DS(on), enabling much higher efficiency at power levels. |
| V_GS(th) Max @ I_D | 1 V @ 1 mA | 1.5 V @ 250 µA | UM6K33NTN turns on at lower gate threshold voltage, beneficial for low-voltage logic drive. |
| Technology | MOSFET (Metal Oxide) | MOSFET (Metal Oxide) | Both are MOSFETs; no technology difference noted. |
Design trade-offs
The UM6K33NTN and AOSS32338C target fundamentally different segments despite both being N-channel MOSFETs. The UM6K33NTN is a dual MOSFET array optimized for low-voltage, low-current switching with logic-level gate drive as low as 1.2 V. Its extremely low input capacitance (25 pF) and low gate threshold voltage enable efficient switching with minimal gate drive power, which is ideal for battery-powered or low-voltage digital control circuits. However, its maximum continuous current rating is only 200 mA with a high R_DS(on) of 2.2 Ω, restricting it to signal-level or very low power loads. Its power dissipation limit of 120 mW also mandates careful thermal design to avoid overheating.
On the other hand, the AOSS32338C is designed for power switching applications requiring up to 4 A continuous current and capable of dissipating 1.3 W at ambient temperature. Its R_DS(on) of 50 mΩ at 10 V gate drive is orders of magnitude lower than UM6K33NTN, supporting significantly higher efficiency and reduced conduction losses in load-switching or DC-DC converter applications. The trade-off is a higher gate drive voltage requirement (2.5 V minimum for specified R_DS(on)) and a much higher input capacitance (340 pF), which increases gate charge and switching losses. This means the gate driver or MCU GPIO needs sufficient drive strength and possibly a dedicated MOSFET driver IC.
Thermal management is another critical difference. The AOSS32338C’s SOT-23-3 package supports higher power dissipation but requires careful PCB layout with adequate copper area for heat sinking. The UM6K33NTN’s smaller package and lower power dissipation simplify thermal design, but the dual MOSFET configuration may require more complex routing if used as discrete switches. From a firmware perspective, the lower gate threshold and logic-level drive of UM6K33NTN simplify interfacing with low-voltage MCUs without additional gate drivers, whereas AOSS32338C may necessitate a driver stage to reach 10 V gate drive for optimal R_DS(on).
In volume production, the cost per unit will likely be lower for the UM6K33NTN given its smaller size and simpler requirements, but total system cost must consider accompanying driver components and thermal solutions. The AOSS32338C’s higher power capability justifies its cost in power stages but may be overkill and inefficient in signal-level switching.
Use-case fit
Choose UM6K33NTN when…
- You need dual N-channel MOSFETs in a compact 6-pin package for level shifting or half-bridge low current switching below 200 mA.
- Your application runs on low-voltage logic signals (1.2 V gate drive) and cannot afford additional gate driver circuitry.
- Minimizing gate charge and input capacitance is crucial to reduce switching losses and EMI in high-frequency digital circuits.
- Your voltage rail is up to 50 V, higher than typical low-voltage MOSFETs can handle.
- Power dissipation is limited (under 120 mW), and you prioritize small size and integration over conduction efficiency.
Choose AOSS32338C when…
- You require switching currents up to 4 A continuous, such as in load switching, power rails, or DC-DC converters.
- Low R_DS(on) (50 mΩ max @ 4 A, 10 V gate) is critical to minimize conduction losses and improve efficiency.
- The gate drive voltage can be provided at 10 V or at least 2.5 V to fully enhance the MOSFET.
- Your design must dissipate up to 1.3 W in the MOSFET package and you can implement sufficient PCB thermal management.
- You need a MOSFET rated for operation down to -55°C for automotive or industrial temperature ranges.
Drop-in compatibility
The UM6K33NTN is a dual MOSFET array in a 6-pin UMT6 package (6-TSSOP/SC-88/SOT-363 style), whereas the AOSS32338C is a single MOSFET in a 3-pin SOT-23-3 package. These packages are not footprint-compatible, nor are the pinouts similar due to differing device counts and functions. Substituting one for the other is not a simple drop-in replacement and would require redesign of the PCB footprint and potentially the circuit topology. Additionally, the gate drive voltage requirements and electrical ratings differ significantly, so direct substitution without re-evaluation of gate drive and load conditions is not recommended.
Alternatives to consider
- BSS138 (ON Semiconductor / Nexperia): A common low-voltage N-channel MOSFET with logic-level gate drive and low input capacitance, suitable for low-current switching similar to UM6K33NTN.
- Si2302DS (Vishay): A 30 V, 2.3 A logic-level MOSFET with low R_DS(on) and SOT-23 package, bridging the gap between signal-level and power MOSFETs.
- IRLML6344 (Infineon): Logic-level N-channel MOSFET with very low gate charge and R_DS(on), good for low-voltage, moderate current switching applications.