NXP Semiconductors BUK9509-55A,127

Overview

BUK9509-55A from NXP Semiconductors (formerly Philips) is an N-channel TrenchMOS™ logic-level power MOSFET in SOT78 (TO-220AB) package, rated for 55 V drain-source voltage, 108 A DC drain current at T_mb = 25 °C and V_GS = 5 V, with typical R_DS(on) of 7.6 mΩ at V_GS = 5 V and 25 A. It serves as a high-current, low-R_DS(on) switching device in automotive 12 V/24 V load control circuits.

For engineers reviewing the BUK9509-55A datasheet, BUK9509-55A pinout, BUK9509-55A application, or BUK9509-55A equivalent, this page delivers verified electrical specs, thermal behavior, gate drive compatibility, mounting-base thermal resistance, and real-world automotive switching use cases - all confirmed from the official 2002 product data sheet.

Technical Context

This MOSFET uses TrenchMOS™ technology to achieve low on-resistance while maintaining robust avalanche ruggedness (400 mJ unclamped inductive energy). Its logic-level gate threshold (V_GS(th) = 1–2 V typ.) enables direct drive from 3.3 V or 5 V microcontrollers without level-shifting.

Thermal design centers on junction-to-mounting-base resistance (R_th(j-mb) ≤ 0.71 K/W), requiring heatsink attachment to the metal mounting base (pin 2, internally connected to drain). The device is Q101-qualified and rated for continuous operation up to 175 °C junction temperature.

Key Specifications

Pinout & Package

SOT78 (TO-220AB) plastic single-ended package with metal mounting base acting as both mechanical heatsink interface and electrical connection to drain. Mounting base is electrically tied to pin 2 (drain).

Key Features

Applications

Equivalent & Alternatives

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

Compared with STP110N55F7 and IRF1404ZLPbF, the BUK9509-55A uniquely combines Q101 qualification, true logic-level gate (1.5 V typ. threshold), and 55 V rating in a standard TO-220AB - making it the only option validated for automotive body electronics with minimal gate drive overhead.

Availability

BUK9509-55A is available at Aetrix Electronics and suitable for automotive body control modules, industrial 24 V motor drives, and off-highway solenoid control systems requiring stable component supply across extended production lifecycles.

Supply support for BUK9509-55A 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 leader focused on secure connectivity solutions for automotive, industrial, and IoT applications. Formerly part of Philips, its power MOSFET portfolio emphasizes reliability and system-level robustness.

The BUK95xx series was designed specifically for automotive power switching - delivering logic-level drivability, AEC-Q101 qualification, and high-current capability in thermally optimized TO-220AB packages for under-hood and chassis-mounted control units.

FAQ

What is the maximum continuous drain current for BUK9509-55A at 100 °C mounting base temperature?

The BUK9509-55A supports 75 A continuous drain current at T_mb = 100 °C and V_GS = 5 V, as specified in Table 3 (Limiting Values). This derating reflects package thermal limits rather than silicon capability - the die itself remains functional up to 175 °C junction temperature, but power dissipation is constrained by the TO-220AB package's ability to transfer heat at elevated base temperatures.

Is BUK9509-55A pin-compatible with BUK9609-55A?

No, BUK9509-55A and BUK9609-55A are not pin-compatible. BUK9509-55A uses SOT78 (TO-220AB) with three leads and a mounting base tied to drain, while BUK9609-55A uses SOT404 (D2-PAK) - a surface-mount package with different footprint, lead configuration, and thermal interface geometry. Their pin numbering differs, and mechanical mounting requirements are incompatible.

Does BUK9509-55A have integrated gate protection diodes?

No, the BUK9509-55A does not include integrated gate protection diodes. The datasheet specifies gate-source leakage current (I_GSS) of up to 100 nA at ±10 V, and absolute maximum V_GS is ±15 V - indicating external gate protection (e.g., Zener clamp or RC snubber) is required in noisy automotive environments to prevent ESD or transient-induced gate oxide damage.

Can BUK9509-55A be used in high-frequency PWM applications above 100 kHz?

BUK9509-55A is not optimized for high-frequency PWM above 100 kHz. Its total gate charge (Q_g(tot)) is 60 nC and rise/fall times are 149 ns/131 ns - resulting in significant switching losses at high frequencies. It is best suited for <50 kHz switching (e.g., lamp dimming, solenoid timing) or DC-on/off control where low R_DS(on) and avalanche ruggedness outweigh switching speed.

What is the thermal resistance from junction to ambient for BUK9509-55A in free-air conditions?

The BUK9509-55A has a junction-to-ambient thermal resistance (R_th(j-a)) of 60 K/W in vertical mounting position with still air, per Table 4. This value assumes no heatsink - practical use requires mounting the device's metal base to a heatsink to achieve the much lower R_th(j-mb) ≤ 0.71 K/W, which dominates thermal performance in real applications.