NXP Semiconductors BUK129-50DL,118

Overview

BUK129-50DL from NXP Semiconductors (formerly Philips) is a monolithic, temperature- and overload-protected logic-level power MOSFET in TOPFET2 technology, assembled in SOT404 (D2-PAK) package. It delivers 16 A continuous drain current at 50 V V_DS, 50 mΩ R_DS(ON) at 25 °C, and integrated overvoltage clamping for inductive load turn-off - used as a robust high-side switch in automotive lamp and solenoid control.

For engineers reviewing the BUK129-50DL datasheet, BUK129-50DL pinout, BUK129-50DL application, or BUK129-50DL equivalent, key selection criteria include its 5 V logic-compatible input, latch-reset protection architecture, thermal shutdown threshold at 150 °C, and 200 mJ non-repetitive clamping energy - critical for reliable 12 V automotive load switching without external flyback diodes.

Technical Context

The BUK129-50DL integrates a TrenchMOS output stage with on-chip current limiting, overtemperature trip (T_j(TO) = 150–170 °C), and latched protection reset via input voltage cycling. Its logic input derives supply and control for all protection circuits, eliminating external bias rails.

It features active overvoltage clamping above 50 V (V_(CL)DSS = 50–70 V), ESD protection per human-body model (2 kV), and input series resistance (R_IG = 33 kΩ) to gate - enabling direct microcontroller drive with only 400 µA typical I_IS at 5 V.

Key Specifications

Pinout & Package

Package: SOT404 (D2-PAK variant), plastic surface-mount, 3-pin configuration with mounting base (pin 2 and mb both connected to drain). Thermal resistance R_{th j-mb} = 1.75–1.92 K/W enables efficient heat transfer to PCB copper pour or heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STI129N50L and BTS50080-1TAD, the BUK129-50DL offers a minimal, self-contained high-side switch solution with built-in clamping and latched fault management - ideal for cost-sensitive, space-constrained automotive modules where simplicity and reliability outweigh programmability or ultra-high current needs.

Availability

BUK129-50DL is available at Aetrix Electronics and suitable for automotive lamp control, solenoid actuation, heater regulation, and auxiliary motor switching requiring stable component supply and long-term lifecycle support.

Supply support for BUK129-50DL 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 leader focused on automotive, industrial, and IoT applications, delivering secure, energy-efficient, and highly integrated solutions.

The BUK129-50DL belongs to NXP's TOPFET family of intelligent power switches, designed specifically for robust, low-complexity high-side load control in harsh automotive environments - emphasizing protection integration, thermal resilience, and direct microcontroller interfacing.

FAQ

What is the maximum continuous drain current rating for BUK129-50DL?

The BUK129-50DL supports 16 A continuous drain current at T_mb ≤ 125 °C with V_IS = 5 V. At 25 °C mounting base temperature, current is self-limited by thermal design; derating applies above 125 °C. This rating enables direct driving of high-power lamps and solenoids without external current amplification. The BUK129-50DL datasheet specifies ID = 16 A as the guaranteed operational limit under defined thermal conditions.

Does BUK129-50DL require an external flyback diode when switching inductive loads?

No, the BUK129-50DL includes integrated active overvoltage clamping that handles inductive kickback up to 200 mJ non-repetitively. When V_DS exceeds 50 V during turn-off, the internal MOSFET turns on to clamp the transient, eliminating the need for an external flyback diode in most automotive solenoid and relay applications. This feature is confirmed in the BUK129-50DL overvoltage clamping limiting values table.

How does the overload protection reset mechanism work in BUK129-50DL?

The BUK129-50DL uses a latched protection architecture: once tripped by overtemperature or overload, it remains off until the input voltage (VIS) is cycled below the reset threshold (VISR = 1.5–2.9 V) for ≥100 µs. This ensures fault persistence until deliberate system intervention. The BUK129-50DL input characteristics section confirms latched behavior and specifies t_lr = 10–100 µs for reset timing.

What is the thermal resistance from junction to mounting base for BUK129-50DL?

The BUK129-50DL has a junction-to-mounting-base thermal resistance (R_{th j-mb}) of 1.75–1.92 K/W, measured under standard test conditions. This low value enables efficient heat transfer to PCB copper or heatsinks, supporting >30 W power dissipation with ≤60 K temperature rise. The BUK129-50DL thermal characteristics table lists this parameter explicitly for SOT404 package mounting.

Is BUK129-50DL compatible with 3.3 V microcontroller GPIO outputs?

Yes - the BUK129-50DL input threshold voltage (VIS(TO)) ranges from 0.6 V to 2.4 V, and its input supply current (I_IS) is only 80–330 µA at V_IS = 4 V. A 3.3 V GPIO easily exceeds the 2.4 V max threshold and provides sufficient margin for noise immunity. The BUK129-50DL input characteristics confirm operation down to 4 V, making it fully compatible with 3.3 V logic systems without level shifting.