NXP Semiconductors BUJ403A/DG,127

Overview

BUJ403A/DG,127 from NXP Semiconductors is a high-voltage, high-speed npn silicon power transistor in TO220AB package, rated for 1200 V V_CESM, 6 A DC collector current, and 100 W total power dissipation at T_mb ≤ 25 °C. It serves as a primary switching device in electronic lighting ballasts, high-frequency inverters, and motor control systems where fast turn-off and robust voltage blocking are required.

For engineers reviewing the BUJ403A/DG,127 datasheet, BUJ403A/DG,127 pinout, BUJ403A/DG,127 application, or BUJ403A/DG,127 equivalent, key selection criteria include its 170 ns typical fall time under inductive load, 550 V V_CEO rating, collector-emitter sustaining voltage of 550 V, and thermal resistance R_{th j-mb} of 1.25 K/W - all critical for reliable operation in high-frequency switching topologies with elevated ambient or mounting base temperatures.

Technical Context

The BUJ403A/DG,127 employs planar passivation and diffusion technology to achieve stable high-voltage operation up to 1200 V peak collector-emitter voltage with low saturation voltage (0.15 V typ at I_C = 2 A, I_B = 0.4 A). Its dynamic performance is optimized for inductive switching: 170–300 ns fall time and ≤1.8 µs storage time at T_j = 100 °C ensure minimal switching losses in resonant and hard-switched converters.

Thermal design is enabled by direct collector-to-mounting-base connection (tab = collector), yielding a low junction-to-mounting-base thermal resistance of 1.25 K/W max. The device operates safely up to 150 °C junction temperature and supports reverse-bias safe operating area (RBSOA) up to 1000 V clamp voltage with 1 µH inductive load, making it suitable for snubberless or minimally snubbed high-voltage switching stages.

Key Specifications

Pinout & Package

Package: TO220AB - plastic-encapsulated power package with insulated mounting base; tab electrically connected to collector; net mass 2 g; UL94 V0 compliant epoxy.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar npn high-voltage power switching applications.

Compared with STW12NK120Z and BUJ303A,127, the BUJ403A/DG,127 delivers superior high-voltage ruggedness and faster switching in bipolar-driven topologies, but requires sustained base current - making it optimal for fixed-frequency, high-reliability ballast and inverter designs where V_CESM > 1100 V and t_f < 300 ns are mandatory.

Availability

BUJ403A/DG,127 is available at Aetrix Electronics and suitable for electronic lighting ballasts, high-frequency inverters, and industrial motor control systems requiring stable component supply, long-lifecycle support, and traceable sourcing for production programs.

Supply support for BUJ403A/DG,127 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 high-performance analog, logic, and power discrete solutions for industrial, automotive, and consumer markets.

The BUJ403A/DG,127 belongs to NXP's high-voltage npn power transistor product line, engineered specifically for demanding high-frequency switching applications such as electronic lighting ballasts and resonant power conversion where voltage endurance, switching speed, and thermal robustness are co-critical.

FAQ

What is the maximum junction temperature specification for BUJ403A/DG,127?

The BUJ403A/DG,127 has a maximum junction temperature (T_j) rating of 150 °C, as defined in the Limiting Values section of its NXP datasheet. This value governs thermal design margins and must be respected during steady-state and transient operation. Derating curves in Figure 7 confirm that full 100 W power dissipation is only permissible at mounting base temperatures ≤25 °C; BUJ403A/DG,127 must be thermally managed to ensure T_j does not exceed 150 °C under worst-case load and ambient conditions.

Is BUJ403A/DG,127 pin-compatible with BUJ303A,127?

Yes, BUJ403A/DG,127 is pin-compatible with BUJ303A,127 - both use the TO220AB package with identical pin 1 (base), pin 2 (collector), pin 3 (emitter), and collector-connected tab layout. However, BUJ403A/DG,127 offers higher voltage ratings (1200 V V_CESM vs. 1000 V) and 550 V V_CEO vs. 450 V, so direct substitution requires verification of voltage stress margins in the target application before deploying BUJ403A/DG,127.

What base drive current is required to saturate BUJ403A/DG,127 at 3 A collector current?

To achieve full saturation at I_C = 3 A, BUJ403A/DG,127 requires a minimum DC base current of 194 mA, derived from its h_FEsat minimum of 15.5 (I_B = I_C/h_FEsat = 3 A / 15.5 ≈ 0.194 A). The datasheet specifies h_FEsat = 15.5 at I_C = 3 A and V_CE = 5 V. Operating BUJ403A/DG,127 with less base drive risks increased V_CEsat and thermal runaway under load.

Does BUJ403A/DG,127 have an integrated antiparallel diode?

No, BUJ403A/DG,127 does not include an integrated antiparallel (freewheeling) diode. As a discrete npn bipolar junction transistor, it conducts only from collector to emitter when forward-biased and base-driven. External diodes - such as ultrafast recovery types - must be added across the collector-emitter terminals in inductive switching applications to provide safe current recirculation paths during turn-off.

What is the thermal resistance from junction to mounting base for BUJ403A/DG,127?

The maximum thermal resistance from junction to mounting base (R_{th j-mb}) for BUJ403A/DG,127 is 1.25 K/W, as specified in the Thermal Resistances section of the NXP datasheet. This value assumes proper mechanical mounting with recommended torque and thermal interface material. Because the collector is directly connected to the metal tab, this low R_{th j-mb} enables efficient heat transfer to the heatsink - a key advantage of BUJ403A/DG,127 in space-constrained power designs.