NXP Semiconductors BUK108-50DL,118

Overview

BUK108-50DL from NXP (formerly Philips Semiconductors) is a monolithic, temperature- and overload-protected logic-level PowerMOS transistor in SOT404 (TO-263) package, designed as a general-purpose automotive switch. It features 50 V drain-source voltage rating, 13.5 A continuous drain current at 25 °C, 125 mΩ typical R_DS(ON), integrated overvoltage clamping, and 5 V logic-compatible input for direct microcontroller drive.

For engineers reviewing the BUK108-50DL datasheet, BUK108-50DL pinout, BUK108-50DL application, or BUK108-50DL equivalent, key selection considerations include its latched short-circuit protection with 0.8 ms response time, 150 °C junction temperature limit, 70 V clamping voltage under transient conditions, and thermal resistance of 2.5–3.1 K/W from junction to mounting base - critical for high-reliability automotive load switching.

Technical Context

The BUK108-50DL integrates a vertical DMOS power stage with on-chip logic and protection circuitry powered directly from the input pin. Its protection architecture includes two independent latched trip mechanisms: one triggered by junction temperature exceeding 150 °C, and another by short-circuit energy accumulation exceeding 0.2 J at 13 V supply.

Overvoltage clamping activates above 50 V (typ. 70 V at 1 A), sinking up to 15 A repetitively with 20 mJ repetitive clamping energy at 95 °C. Input threshold voltage is 1.0–2.0 V, enabling compatibility with 3.3 V and 5 V controllers, while input supply current remains ≤350 µA during normal operation.

Key Specifications

Pinout & Package

SOT404 (TO-263) surface-mount package with exposed metal mounting base (pin 2 and mb both connected to drain). The tab is electrically connected to the drain terminal and serves as primary thermal path.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side protected MOSFET applications.

Compared with BUK108-50DL, STB13NK50Z offers higher voltage tolerance but lacks all on-chip protection, increasing BOM count and layout complexity; BTS50085-1TAD adds intelligence and diagnostics at the cost of higher system integration effort and price - BUK108-50DL remains optimal for cost-sensitive, protection-critical high-side switches where simplicity and proven automotive robustness are prioritized.

Availability

BUK108-50DL is available at Aetrix Electronics and suitable for automotive lamp control, DC motor actuation, solenoid driving, and heater load management requiring stable component supply across extended temperature and reliability cycles.

Supply support for BUK108-50DL 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 specializing in secure connectivity solutions for automotive, industrial, and IoT applications, with roots in Philips' semiconductor division.

The TOPFET product line - including BUK108-50DL - was engineered specifically for automotive body electronics, delivering integrated protection, logic-level drive, and rugged packaging to replace relay-based and discrete MOSFET+protection designs.

FAQ

What is the maximum continuous drain current for BUK108-50DL at 100 °C mounting base temperature?

The BUK108-50DL supports 8.5 A continuous drain current when the mounting base temperature is maintained at or below 100 °C, as specified in the Limiting Values table. This derating reflects thermal constraints of the SOT404 package and internal power dissipation limits. Engineers must ensure adequate PCB copper area and heatsinking to sustain this current without exceeding the 150 °C junction temperature limit. The BUK108-50DL datasheet provides normalized derating curves for precise thermal design.

Does BUK108-50DL require an external flyback diode when switching inductive loads?

No, the BUK108-50DL does not require an external flyback diode because it incorporates active overvoltage clamping that turns on the internal MOSFET when V_DS exceeds ~50 V, limiting transients to ≤70 V. This feature safely dissipates inductive energy up to 200 mJ non-repetitively and 20 mJ repetitively. However, for very high-energy or high-frequency inductive switching, external energy absorption may still be advisable. The BUK108-50DL's clamping behavior is fully characterized in its datasheet Figures 12 and 19.

How is overload protection reset on BUK108-50DL after a latched fault condition?

Overload protection on the BUK108-50DL is reset by cycling the input voltage (pin 1) below the reset threshold of 2.0–3.5 V - typically achieved by pulling the input low for ≥100 µs. The device remains latched off until this reset occurs, preventing automatic re-engagement during fault persistence. Input supply current drops to ≤650 µA in latched state, enabling low-power fault detection. This behavior is confirmed in the OVERLOAD PROTECTION CHARACTERISTICS section of the BUK108-50DL datasheet.

What is the typical R_DS(ON) of BUK108-50DL at 7.5 A and 25 °C junction temperature?

The typical R_DS(ON) of the BUK108-50DL is 85 mΩ when tested at 7.5 A drain current, 5 V input voltage, and 25 °C junction temperature, per the STATIC CHARACTERISTICS table. This value increases with temperature - Figure 8 shows normalized R_DS(ON) rising to ~1.5× at 125 °C. Designers should use the 125 mΩ maximum value for worst-case conduction loss calculations. The BUK108-50DL's low on-resistance minimizes I²R heating in automotive load applications.

Can BUK108-50DL be driven directly by a 3.3 V microcontroller GPIO pin?

Yes, the BUK108-50DL can be driven directly by a 3.3 V microcontroller GPIO pin because its input threshold voltage (V_IS(TO)) is specified from 1.0 V to 2.0 V, ensuring reliable turn-on at 3.3 V. Input supply current remains ≤270 µA at 3.5 V, well within typical MCU I/O sink/source capability. The BUK108-50DL also includes ESD protection (2 kV HBM), enhancing robustness against GPIO interface transients. No external level shifter or buffer is required for 3.3 V logic compatibility.