Nexperia USA Inc. BUK9518-55A,127

Overview

BUK9518-55A from NXP Semiconductors is a logic-level N-channel TrenchMOS FET in TO-220AB (SOT78A) package, rated for 55 V drain-source voltage, 61 A continuous drain current at 25 °C mounting base temperature, and 136 W total power dissipation. It features 12 mΩ typical R_DS(on) at V_GS = 10 V / I_D = 25 A / T_j = 25 °C and is AEC-Q101 qualified for automotive critical loads including solenoids, lamps, and 12 V/24 V motor control.

For engineers reviewing the BUK9518-55A datasheet, BUK9518-55A pinout, BUK9518-55A application, or BUK9518-55A equivalent, key selection factors include its 175 °C junction rating, low 14–18 mΩ R_DS(on) at 5 V gate drive, avalanche energy rating of 127 mJ, and thermal resistance of 1.1 K/W from junction to mounting base - all critical for thermally constrained automotive power switching designs.

Technical Context

This device implements a trench-gate MOSFET structure optimized for low conduction loss and robustness under repetitive thermal cycling. Its gate threshold voltage (V_GS(th)) ranges from 0.5 V at 175 °C to 2.3 V at −55 °C, enabling reliable turn-on across full automotive temperature range with standard 5 V logic drivers.

The integrated source-drain diode exhibits 0.85–1.2 V forward voltage at 20 A and 25 °C, with 53 ns reverse recovery time and 101 nC recovered charge - parameters directly influencing commutation losses in inductive load switching. Its 3.5 nH internal drain inductance (mounting base to die) supports stable high-speed switching when properly heatsinked.

Key Specifications

Pinout & Package

TO-220AB (SOT78A) plastic single-ended package with heatsink-mounted mounting base electrically connected to drain. Three leads: Gate (pin 1), Drain (pin 2 + mounting base), Source (pin 3).

Key Features

Applications

Equivalent & Alternatives

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

Compared with STL220N5LF5 and IRF1404ZLPBF, BUK9518-55A uniquely balances AEC-Q101 compliance, 5 V logic compatibility, 55 V rating, and 175 °C operation - making it the only drop-in solution for thermally demanding automotive 12 V/24 V load switching without gate boosting or derating.

Availability

BUK9518-55A is available at Aetrix Electronics and suitable for automotive body electronics, 12 V/24 V motor control, and industrial solenoid actuation requiring stable component supply across extended temperature and lifetime requirements.

Supply support for BUK9518-55A 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 markets.

This device belongs to NXP's TrenchMOS logic-level power FET product line, engineered specifically for replacing electromechanical relays and discrete driver stages in automotive power distribution and load control systems.

FAQ

Is BUK9518-55A suitable for high-frequency PWM switching?

Yes - with 95 ns turn-off delay and 97 ns fall time at V_GS = 5 V, it supports PWM frequencies up to 100 kHz in well-designed gate-drive circuits. However, its 14 nC Q_GD and 34 nC Q_G(tot) require careful gate resistor selection to balance switching speed and EMI; thermal performance remains stable up to 20 kHz continuous operation with proper heatsinking.

What is the maximum allowable mounting base temperature for continuous 61 A operation?

The datasheet specifies 61 A continuous drain current only at T_mb = 25 °C. At T_mb = 100 °C, the rated current drops to 43 A per Figure 1. Sustained 61 A operation requires active cooling or forced airflow to maintain mounting base below 25 °C - otherwise, thermal derating must be applied using the normalized curve in Figure 1.

Does the mounting base require electrical isolation from the heatsink?

Yes - because the mounting base is internally connected to the drain terminal (pin 2), it must be electrically isolated from any grounded heatsink using an insulating washer and shoulder washer kit. Failure to isolate creates a short circuit between drain and system ground, destroying the device and potentially damaging upstream circuitry.

Can BUK9518-55A replace a mechanical relay in a 24 V automotive lamp circuit?

Yes - its 55 V V_DS, 61 A I_D, and 127 mJ avalanche rating make it suitable for direct replacement of 30–40 A SPST relays in headlamp, fog lamp, and auxiliary lighting circuits. Unlike relays, it offers silent operation, no contact wear, and precise PWM dimming capability - provided gate drive is clean and layout minimizes parasitic inductance.