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Home > Products > Discrete Semiconductor Products > Transistors > FETs, MOSFETs > FETs, MOSFETs

Nexperia USA Inc. BUK9840-55/CUX

Name: BUK9840-55/CUX
Brand: Nexperia USA Inc.
SKU: BUK9840-55/CUX
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BUK9840-55/CUX

Manufacturer:: Nexperia USA Inc.

Category:: FETs, MOSFETs

Package:: TO-261-4, TO-261AA

Datasheet:: BUK9840-55/CUX.pdf

Description:: MOSFET N-CH 55V 5A/10.7A SOT223

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Product details

Overview

BUK9840-55/CUX from NXP Semiconductors is an AEC-Q101-qualified N-channel TrenchMOS logic-level power MOSFET in SOT223 (SC-73) package, rated for 55 V V_DS, 10.7 A continuous drain current at T_sp = 25 °C, and 30–40 mΩ R_DS(on) at V_GS = 5 V and T_j = 25 °C. It delivers low conduction loss and integrated ESD protection for automotive power switching circuits such as body control modules and lighting drivers.

For engineers reviewing the BUK9840-55/CUX datasheet, BUK9840-55/CUX pinout, BUK9840-55/CUX application, or BUK9840-55/CUX equivalent, key selection criteria include its logic-level gate drive compatibility (V_GS(th) = 1–2 V), avalanche ruggedness (60 mJ), thermal resistance (R_th(j-sp) = 12–15 K/W), and AEC-Q101 qualification for under-hood automotive use.

Technical Context

This MOSFET employs TrenchMOS technology to achieve low on-resistance with logic-level gate drive capability-enabling direct interface with 3.3 V or 5 V microcontrollers without level-shifting. Its dual-drain pin configuration (Pins 2 and 4) enhances thermal performance by increasing heatsink contact area in the SOT223 package.

The device features a robust source-drain diode (V_SD = 0.85–1.1 V at I_S = 5 A), reverse recovery time (t_rr = 45 ns), and non-repetitive avalanche energy rating (E_DS(AL)S = 60 mJ), supporting inductive load switching in automotive solenoid and motor control applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_DS	55 V - Maximum drain-source blocking voltage; supports 24 V automotive systems with margin for load dump transients.
I_D (continuous)	10.7 A at T_sp = 25 °C - Continuous current capability suitable for high-side switches in HVAC actuators or seat control modules.
R_DS(on)	30–40 mΩ at V_GS = 5 V, I_D = 5 A, T_j = 25 °C - Low conduction loss enabling <1 W dissipation at 5 A, reducing heatsink requirements.
E_DS(AL)S	60 mJ unclamped - Avalanche energy rating allows safe operation during inductive turn-off without external snubbers in relay or fuel injector drivers.
V_GS(th)	1–2 V - Logic-level threshold ensures reliable turn-on with standard 3.3 V/5 V MCU GPIOs, eliminating need for gate driver ICs.
R_th(j-sp)	12–15 K/W - Junction-to-solder-point thermal resistance enables effective heat transfer to PCB copper pour, critical for sustained operation in compact automotive ECUs.

Pinout & Package

SOT223 (SC-73) plastic surface-mounted package with increased heatsink area and 4 leads; Pin 1 = Gate, Pins 2 & 4 = Drain (internally connected), Pin 3 = Source.

Pin/Terminal	Circuit Role	Design Meaning
1	Gate	Control terminal accepting logic-level input; low input capacitance (C_iss = 1050–1400 pF) minimizes drive power and switching loss.
2	Drain	Main high-side power path; electrically tied to Pin 4 for doubled solder-pad thermal conduction to PCB.
3	Source	Power return node and reference for gate drive; also serves as cathode of integrated body diode.
4	Drain	Second drain connection-mirrors Pin 2 to improve thermal spreading and current sharing in high-current PCB layouts.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive-grade reliability including temperature cycling, humidity testing, and mechanical shock per AEC standard.
Integrated ESD protection	HBM ESD rating ≥2 kV enables robust handling in automated assembly and reduces need for external TVS components.
Low R_DS(on) at 5 V drive	30–40 mΩ at V_GS = 5 V eliminates requirement for dedicated gate drivers in 5 V MCU-based systems.
Enhanced thermal pad design	SOT223 package with extended drain pads (Pins 2 & 4) lowers R_th(j-sp) to 12–15 K/W for improved power density.

Applications

Body Control Module (BCM)

Automotive Lighting Driver

Use Scenario: Switching 12 V loads such as door locks, window lifters, and mirror adjusters in centralized vehicle body controllers.

IC Role / Device Role / Timing Role: High-side load switch providing controlled power delivery with diagnostic feedback via current sensing.

Use Value: Logic-level gate drive enables direct MCU control; avalanche rating handles inductive kickback from DC motors without snubber networks.

Use Scenario: Driving LED headlamps and daytime running lights (DRL) requiring PWM dimming and overcurrent protection.

IC Role / Device Role / Timing Role: Constant-current switch operating at 100–1 kHz PWM frequencies with fast turn-on/off (t_r/t_f ≤ 100 ns).

Use Value: Low R_DS(on) minimizes thermal rise during high-duty-cycle operation; integrated diode supports freewheeling in buck-derived LED drivers.

Fuel Injector Driver

HVAC Blower Motor Control

Use Scenario: Controlling peak currents up to 12 A in gasoline/diesel engine fuel injectors with precise timing windows.

IC Role / Device Role / Timing Role: Fast-switching low-side or high-side driver synchronized to engine crankshaft position signals.

Use Value: 60 mJ avalanche energy rating absorbs inductive energy during rapid turn-off, preventing voltage overshoot beyond 55 V rating.

Use Scenario: Regulating airflow in vehicle heating, ventilation, and air conditioning systems using brushed DC blowers.

IC Role / Device Role / Timing Role: PWM-controlled power stage delivering variable speed control with thermal derating up to 100 °C solder point temperature.

Use Value: Normalized P_tot curve (Fig. 4) confirms 50% power capability at T_sp = 100 °C, supporting under-dash mounting near heat sources.

Equivalent & Alternatives

The following parts are listed as comparable options for similar N-channel logic-level MOSFET applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
STL130N5LF5	55 V, 130 A (TO-220FP), R_DS(on) = 3.5 mΩ @ 10 V - higher current, higher drive voltage required.	Requires 10 V gate drive; unsuitable for direct 3.3 V MCU interface without level shift.	Select only when >10 A continuous current and TO-220 thermal mass are needed; not drop-in compatible.
ON Semiconductor NTMFS4C09NT1G	40 V, 100 A (SO-8FL), R_DS(on) = 3.1 mΩ @ 10 V - lower voltage rating, different package footprint.	Not rated for 55 V automotive transients; SO-8FL lacks thermal pad area of SOT223.	Use only in 12 V-only systems with strict board space constraints; verify transient immunity separately.

Compared with STL130N5LF5 and NTMFS4C09NT1G, the BUK9840-55/CUX uniquely balances AEC-Q101 compliance, SOT223 thermal efficiency, 5 V logic compatibility, and 55 V transient margin-making it optimal for space-constrained, high-reliability automotive power nodes where gate drive simplicity and thermal management are co-critical.

Availability

BUK9840-55/CUX is available at Aetrix Electronics and suitable for automotive body electronics, lighting control, fuel system actuation, and HVAC blower motor regulation requiring stable component supply across production lifecycles.

Supply support for BUK9840-55/CUX includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The BUK9840-55/CUX belongs to NXP's TrenchMOS logic-level power MOSFET product line, engineered specifically for AEC-Q101-compliant automotive power switching where low gate drive voltage, high avalanche ruggedness, and thermally efficient packaging are essential.

FAQ

Is BUK9840-55/CUX pin-compatible with BUK9840-55?

Yes-BUK9840-55/CUX and BUK9840-55 share identical SC-73 (SOT223) package outline, pin assignment (Pin 1 = G, Pins 2 & 4 = D, Pin 3 = S), and electrical specifications. The "/CUX" suffix denotes a specific tape-and-reel packaging variant compliant with J-STD-020 moisture sensitivity level 1, with no functional or parametric difference.

What is the maximum junction temperature during continuous operation?

The absolute maximum junction temperature (T_j) is 150 °C per IEC 60134 limiting values. For continuous operation, thermal design must ensure T_j remains ≤150 °C-achievable up to 6.8 A at T_sp = 100 °C (per Table 5), assuming proper PCB copper area and airflow per Figure 4's normalized P_tot curve.

Does BUK9840-55/CUX require external gate resistors for automotive EMI compliance?

While not mandatory, a 10 Ω gate resistor is recommended (per Fig. 2 test condition) to dampen ringing and limit dV/dt-induced shoot-through in high-noise automotive environments. This value balances switching speed (t_r/t_f ≈ 65–100 ns) and EMI suppression without excessive gate drive power loss.

Can BUK9840-55/CUX be used in parallel configurations?

Parallel operation is feasible but requires careful layout: matched gate trace lengths, individual gate resistors, and symmetrical thermal coupling to PCB copper. The positive temperature coefficient of R_DS(on) (Fig. 10) provides inherent current sharing stability, though derating to ≤8 A per device is advised for long-term reliability in parallel arrays.

BUK9840-55/CUX Specifications

Product attributes: Attribute value

Manufacturer:: Nexperia USA Inc.

Series:: TrenchMOS™

Package/Case:: TO-261-4, TO-261AA

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

FET Type:: N-Channel

Technology:: MOSFET (Metal Oxide)

Drain to Source Voltage (Vdss):: 55 V

Current - Continuous Drain (Id) @ 25°C:: 5A (Ta), 10.7A (Tc)

Drive Voltage (Max Rds On, Min Rds On):: 5V

Rds On (Max) @ Id, Vgs:: 40mOhm @ 5A, 5V

Vgs(th) (Max) @ Id:: 2V @ 1mA

Gate Charge (Qg) (Max) @ Vgs:: -

Vgs (Max):: ±10V

Input Capacitance (Ciss) (Max) @ Vds:: 1400 pF @ 25 V

FET Feature:: -

Power Dissipation (Max):: 8.3W (Tc)

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-223

BUK9840-55/CUX FAQ

1.How can I place an order for BUK9840-55/CUX through Aetrix?

Please submit a Request for Quotation (RFQ) for BUK9840-55/CUX on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BUK9840-55/CUX reliable?

The price and inventory of BUK9840-55/CUX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BUK9840-55/CUX is usually 5 days.

3.What payment methods are accepted for BUK9840-55/CUX?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BUK9840-55/CUX transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BUK9840-55/CUX?

BUK9840-55/CUX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BUK9840-55/CUX order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BUK9840-55/CUX?

For technical support, including BUK9840-55/CUX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BUK9840-55/CUX requirements.

6.How does Aetrix verify that BUK9840-55/CUX is sourced from the original manufacturer or authorized distributors?

All BUK9840-55/CUX products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BUK9840-55/CUX meets industry standards.

7.What is the process for return or replacement of BUK9840-55/CUX?

All BUK9840-55/CUX units undergo pre-shipment inspection (PSI). If there is an issue with BUK9840-55/CUX, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BUK9840-55/CUX part is unused and in its original packaging.

Return procedure for BUK9840-55/CUX:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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