UM6K33NTN vs SSM6N67NU,LF: Component Comparison for Hardware Engineers
Quick verdict
For low-current, low-voltage logic-level switching applications where compact footprint and ultra-low gate drive voltage matter, the UM6K33NTN is the better choice due to its 1.2V logic-level gate and ultra-low current rating. For higher current loads up to 4A at 30V, such as power switching or load drivers, the SSM6N67NU,LF outperforms with its significantly lower Rds(on), higher continuous current, and greater power dissipation capability.
Spec comparison table
| Spec | UM6K33NTN | SSM6N67NU,LF | Notes |
|---|---|---|---|
| Configuration | 2 N-Channel (Dual) | 2 N-Channel (Dual) | Equivalent |
| Continuous Drain Current (Id) @ 25°C | 0.2 A | 4 A | SSM6N67NU,LF supports 20x higher current, enabling higher power loads |
| Drain-Source Voltage Max (Vds) | 50 V | 30 V | UM6K33NTN allows higher voltage applications |
| Logic Level Gate Drive Voltage | 1.2 V | 1.8 V | UM6K33NTN requires lower gate drive voltage, beneficial for low-voltage logic |
| Gate Charge Qg Max (Vgs) | Not specified | 3.2 nC @ 4.5V | Lower gate charge reduces switching losses; UM6K33NTN data unavailable, likely lower |
| Input Capacitance Ciss Max (Vds) | 25 pF @ 10 V | 310 pF @ 15 V | UM6K33NTN has significantly lower input capacitance, reducing gate drive power |
| Mounting Type | Surface Mount | Surface Mount | Equivalent |
| Operating Temperature Range (TJ) | 150 °C | 150 °C | Equivalent |
| Package Case | 6-TSSOP, SC-88, SOT-363 | 6-WDFN Exposed Pad (2x2 mm) | SSM6N67NU,LF has exposed pad for better thermal dissipation |
| Maximum Power Dissipation (Ta) | 120 mW | 2 W | SSM6N67NU,LF handles >16x higher power dissipation, critical for thermal management |
| Rds(on) Max (Id, Vgs) | 2.2 Ω @ 0.2A, 4.5V | 39.1 mΩ @ 2A, 4.5V | SSM6N67NU,LF has drastically lower Rds(on), reducing conduction losses significantly |
| Supplier Device Package | UMT6 | 6-µDFN (2x2) | Different package footprints |
| Technology | MOSFET (Metal Oxide) | MOSFET (Metal Oxide) | Equivalent |
| Threshold Voltage Vgs_th Max (Id) | 1 V @ 1 mA | 1 V @ 1 mA | Equivalent |
Design trade-offs
The most prominent difference lies in current capability and conduction losses. The UM6K33NTN is tailored for low-current (200mA max) applications with a relatively high on-resistance (2.2Ω at 200mA). This translates to about 88mW conduction loss at its max current, which is near its 120mW max power dissipation. In contrast, the SSM6N67NU,LF supports continuous currents up to 4A with a very low Rds(on) of 39.1mΩ at 2A, which means conduction loss at 2A is roughly 156mW — well within its 2W power dissipation capability.
Thermally, the SSM6N67NU,LF’s exposed pad 6-WDFN package enables better heat sinking, allowing it to handle significantly more power without thermal derating. For designs with constrained thermal budgets, the UM6K33NTN’s small packages like UMT6 or SOT-363 have limited dissipation, restricting high-current use.
The gate drive requirements differ meaningfully. UM6K33NTN’s logic-level gate drive at 1.2V is useful for low-voltage digital control directly from low-voltage MCUs or FPGAs without level shifting. The SSM6N67NU,LF requires 1.8V gate drive minimum, which may require a separate driver or level shifter if the logic voltage is lower. The large difference in input capacitance (25pF vs 310pF) means the UM6K33NTN will be easier on gate drivers at high switching frequencies, reducing switching losses and EMI.
Layout sensitivity is another consideration. The SSM6N67NU,LF’s low Rds(on) and high current capability mandate careful PCB layout with thick copper and thermal vias to maximize heat dissipation. The exposed pad must be soldered to an adequate thermal plane. The UM6K33NTN’s low current and power dissipation reduce layout constraints, allowing simpler PCB designs with smaller copper areas.
Cost-wise, the UM6K33NTN’s simpler, lower-power design and more common small-outline packages will generally be less expensive in volume than the more complex WDFN package and higher performance SSM6N67NU,LF. However, the cost difference may be negligible depending on volume and sourcing.
Use-case fit
Choose UM6K33NTN when…
- Switching low-current loads such as signal-level control, analog multiplexing, or low-power load switching under 200mA.
- Operating from low-voltage logic rails (1.8V or lower) where gate drive voltage is limited.
- Space-constrained designs requiring very small packages like SOT-363 or UMT6.
- Applications with minimal heat sinking or limited thermal budget.
- Designs requiring minimal gate drive power and reduced switching losses due to very low input capacitance.
Choose SSM6N67NU,LF when…
- Driving medium power loads up to 4A, such as power rail switches, motor drivers, or high-current load switches.
- Operating at voltages up to 30V with significant transient currents.
- Designs where conduction loss and efficiency are critical, as the low Rds(on) reduces power dissipation.
- Applications requiring robust thermal management, leveraging the exposed pad package for heat dissipation.
- Circuits that can provide 1.8V or higher gate drive voltage for full enhancement.
Drop-in compatibility
These parts are not pin-compatible or footprint-compatible. The UM6K33NTN is offered in 6-TSSOP/SC-88/SOT-363 packages (UMT6 footprint), while the SSM6N67NU,LF uses a 6-pin WDFN 2x2mm exposed pad package. Pin assignments and package outlines differ significantly. Substituting one for the other will require PCB redesign and verification of gate drive voltage compatibility and thermal management.
Alternatives to consider
- BSS138 (NXP, ON Semiconductor): Single N-channel MOSFET with low Rds(on) for low current switching, widely used and inexpensive.
- Si2302 (Vishay): Small logic-level MOSFET with low gate charge and Rds(on), suitable for low-voltage digital switching.
- FDN360P (Fairchild): Dual N-channel MOSFET array with low Rds(on) and moderate current rating for medium load switching applications.