Component Comparison: NX3008NBKS,115 vs FDC638P
Quick verdict
For low-current dual-switch applications requiring logic-level N-channel MOSFETs, especially in automotive environments, the NX3008NBKS,115 is the clear choice due to its dual device configuration, AEC-Q101 qualification, and low voltage rating. For high-current single-switch P-channel applications where low R_DS(on) and compact footprint are critical, the FDC638P outperforms with its 4.5 A rating and extremely low on-resistance, making it suitable for load switching and power path control.
Spec comparison table
| Spec | NX3008NBKS,115 | FDC638P | Notes |
|---|---|---|---|
| FET Type | 2 N-Channel (Dual) | P-Channel | Different polarity; choice depends on circuit topology. |
| Drain-Source Voltage (V_DS max) | ±30 V | 20 V | NX3008NBKS,115 supports higher voltage margin (30 V vs 20 V). |
| Continuous Drain Current (I_D @25°C) | 350 mA | 4.5 A | FDC638P supports >10× higher current, suitable for high load currents. |
| Drain Current Spiking Max | 1.4 A | Not specified | NX3008NBKS,115 allows brief 1.4 A spikes; FDC638P data not given. |
| On-Resistance (R_DS(on)) | 1.4 Ω @ 350 mA, 4.5 V | 48 mΩ @ 4.5 A, 4.5 V | FDC638P has dramatically lower R_DS(on), critical for efficiency at high current. |
| Gate Threshold Voltage (V_GS(th)) | 0.6–1.1 V (typ 0.9 V) @ 250 µA | 1.5 V @ 250 µA | NX3008NBKS,115 has lower V_TH, better for logic-level drive. |
| Gate Charge (Q_g @ 4.5 V) | 0.68 nC | 14 nC | NX3008NBKS,115 requires far less gate charge, easier to drive and faster switching. |
| Input Capacitance (C_iss) | 34–50 pF | 1160 pF @ 10 V | NX3008NBKS,115 has much lower input capacitance, reducing gate drive losses. |
| Output Capacitance (C_oss) | 6.5 pF (typical) | Not specified | NX3008NBKS,115 data only; likely much lower capacitance. |
| Reverse Transfer Capacitance (C_rss) | 2.2 pF (typical) | Not specified | NX3008NBKS,115 data only; lower C_rss helps reduce Miller effect and switching loss. |
| Power Dissipation (P_D max) | 445 mW | 1.6 W (Ta) | FDC638P can dissipate ~3.5× more power at ambient temperature. |
| Package | 6-TSSOP (SOT-363, SC-88) | SuperSOT-6 (TSOT-23-6) | Different package styles; affects PCB layout and thermal performance. |
| Thermal Resistance Junction-to-Ambient | 300 K/W typical (per device) | Not specified | NX3008NBKS,115 data available; FDC638P data not provided. |
| Operating Temperature Range | -55°C to +150°C (TJ) | -55°C to +150°C (TJ) | Equivalent operating temperature ranges. |
| Electrostatic Discharge Rating (ESD) | 2000 V | Not specified | NX3008NBKS,115 rated for 2 kV ESD; FDC638P ESD rating not provided. |
| Gate-Source Voltage Max | ±8 V | ±8 V | Equivalent gate voltage limits. |
| Qualification | AEC-Q101 Automotive | None listed | NX3008NBKS,115 is automotive qualified, critical for automotive/system reliability. |
| Transient Thermal Impedance (Z_th) | 0.01–1 K/W (typical values) | Not specified | NX3008NBKS,115 data allows transient thermal modeling. |
| Input Current (Continuous Drain) | 350 mA (typical) | 4.5 A (typical) | Matches continuous drain current rating; FDC638P supports much higher current. |
| Gate Leakage Current (typ @ 25°C) | 0.2–1 µA | Not specified | NX3008NBKS,115 gate leakage is low; FDC638P data missing. |
| Gate Drive Voltage for R_DS(on) Rating | 4.5 V | 4.5 V | Both rated at 4.5 V gate drive for R_DS(on) data. |
| Device Configuration | Dual MOSFET array (2 devices) | Single device | NX3008NBKS,115 integrates two N-MOSFETs, useful for half-bridge or complementary switches. |
Design trade-offs
The NX3008NBKS,115 and FDC638P target fundamentally different applications due to their polarity, current capability, and device architecture. The NX3008NBKS,115 is a dual N-channel MOSFET array designed for low-current switching or level shifting, with very low input capacitance (34–50 pF) and minimal gate charge (~0.68 nC). This makes it highly suitable for low-power, logic-level driven applications where switching losses and gate drive current must be minimized. Its AEC-Q101 qualification and extended temperature range up to 150°C junction temperature make it a solid choice for automotive-grade designs requiring reliability and robustness.
In contrast, the FDC638P is a single P-channel MOSFET rated for continuous drain currents up to 4.5 A, with an extremely low R_DS(on) of 48 mΩ at 4.5 V gate drive. This low on-resistance translates directly to reduced conduction losses in high-current paths, critical in power distribution, load switching, or battery management circuits. However, it has a substantially higher gate charge (14 nC) and input capacitance (1160 pF), meaning gate drivers must source more current to achieve fast switching, which can increase EMI and losses. The FDC638P’s power dissipation rating of 1.6 W (at ambient) reflects its capability to handle higher power dissipation, but thermal design must ensure adequate heat sinking or PCB copper area.
From a layout perspective, the NX3008NBKS,115’s 6-TSSOP package is compact but has relatively high thermal resistance (~300 K/W), limiting its power handling and requiring careful thermal management. The FDC638P’s SuperSOT-6 package offers a smaller footprint and better thermal conduction paths, better suited for compact high-current power stages. The dual MOSFET configuration of the NX3008NBKS,115 can reduce component count and simplify designs requiring complementary or dual switches, whereas the FDC638P’s single P-channel device is ideal for high-side switching where P-MOSFETs simplify gate drive.
Cost-wise, Nexperia’s NX3008NBKS,115 is likely less expensive per MOSFET due to lower current rating and simpler construction, but the dual device integration adds value. The FDC638P’s higher current rating and specialized package may command a premium, but can reduce total system cost by eliminating external heat sinking or parallel devices.
Use-case fit
Choose NX3008NBKS,115 when…
- Designing low-current dual N-channel switches for signal-level or level-shifting circuits in automotive or industrial environments requiring AEC-Q101 qualification.
- Implementing half-bridge or dual-switch configurations on a tight PCB footprint where integrated dual MOSFETs reduce BOM count.
- Operating circuits with supply voltages up to 30 V and continuous currents under 350 mA, where low gate charge minimizes driver complexity.
- Thermal dissipation is limited and switching frequencies are moderate, leveraging the device’s low input capacitance to reduce switching losses.
- ESD robustness up to 2000 V is required to survive harsh handling or application environments.
Choose FDC638P when…
- Switching or controlling loads with continuous currents up to 4.5 A at 20 V supply voltages, such as battery power paths or motor driver stages.
- A low R_DS(on) P-channel MOSFET is required for high-side switching to simplify gate drive and minimize conduction losses.
- Power dissipation capability up to 1.6 W at ambient temperature is needed, with appropriate PCB thermal design to handle heat.
- Fast switching is needed and gate drive current can be accommodated despite the higher gate charge (14 nC).
- A compact SuperSOT-6 package is preferred to optimize PCB size in power-sensitive applications.
Drop-in compatibility
These two devices are not pin-compatible or footprint-compatible. The NX3008NBKS,115 is a dual N-channel MOSFET array in a 6-TSS