NXP Semiconductors BSN254,126

Overview

BSN254 from Philips Semiconductors is an N-channel enhancement-mode vertical D-MOS transistor in SOT54 (TO-92) package, rated for 250 V drain-source voltage, 310 mA DC drain current, and 1 W total power dissipation at 25 °C ambient. It features low 2.8 Ω typical R_DS(on) at V_GS = 10 V and 300 mA, gate-threshold voltage of 0.8–2 V, and fast switching with 6 ns turn-on and 47 ns turn-off times - used as line current interruptor in telephone sets and high-speed relay drivers.

For engineers reviewing the BSN254 datasheet, BSN254 pinout, BSN254 application, or BSN254 equivalent, key selection criteria include its SOT54 pin configuration (Gate-Source-Drain), 250 V blocking capability, thermal resistance of 125 K/W, and compatibility with CMOS/TTL logic-level drive without external level-shifting.

Technical Context

The BSN254 operates as a single-gate, enhancement-mode power switch with vertical D-MOS architecture enabling high-voltage operation and absence of secondary breakdown. Its gate-source threshold voltage (0.8–2 V) ensures reliable turn-on from standard logic outputs, while its 100 pF typical input capacitance and 21 pF output capacitance support high-speed switching up to tens of MHz in small-signal load-driving applications.

Thermal design is constrained by a junction-to-ambient thermal resistance of 125 K/W under PCB-mount conditions (10 × 10 mm drain pad, ≤4 mm lead length). The device exhibits negative temperature coefficient for R_DS(on), increasing resistance by ~25% from −50 °C to +150 °C, and a decreasing V_GS(th) with rising temperature - critical for stable biasing in wide-temperature industrial telephony circuits.

Key Specifications

Pinout & Package

SOT54 (TO-92 variant) plastic through-hole package with 3 leads; standardized pin spacing (e = 2.54 mm), 14.5 mm body length, and uncontrolled terminal dimensions per zone L1 for mold flow tolerance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BSN254, the BSN254A offers identical performance but demands board-level pinout adaptation, while the 2N7002 trades voltage capability for smaller size and lower gate charge - making it viable only in non-telecom, low-voltage signal-switching roles.

Availability

BSN254 is available at Aetrix Electronics and suitable for telephone line interface, relay driver, and line transformer driver applications requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.

Supply support for BSN254 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

Philips Semiconductors (now NXP Semiconductors) is a global semiconductor innovator founded in the Netherlands, specializing in analog, logic, and power devices for industrial, automotive, and communications markets.

The BSN254 belongs to Philips' vertical D-MOS transistor family designed specifically for high-voltage, low-current switching in telecommunications infrastructure - emphasizing reliability under repetitive surge stress and compatibility with legacy analog telephony standards.

FAQ

What is the maximum drain-source voltage rating for BSN254?

The BSN254 has a maximum drain-source voltage (V_DS) rating of 250 V DC, verified per IEC 60134 absolute maximum ratings. This allows safe operation in telephone line applications with peak ringing voltages up to 90 V and transient surges within telecom-grade protection margins. The BSN254 maintains this rating across its full operating temperature range up to 150 °C junction temperature.

Does BSN254 require a gate resistor for TTL/CMOS drive?

The BSN254 does not require a series gate resistor when driven directly from standard TTL or CMOS outputs, due to its low gate charge and 0.8–2 V threshold voltage. However, a 100 Ω resistor is recommended in high-noise environments to dampen ringing and reduce EMI. The BSN254 gate leakage remains below ±100 nA at ±20 V, ensuring stable logic-level control without unintended turn-on.

Can BSN254 be used in linear (analog) mode, not just switching?

Yes, the BSN254 supports linear-mode operation because its vertical D-MOS structure eliminates secondary breakdown - a key limitation of many planar MOSFETs. In telephone line current regulation or analog signal switching, the BSN254 can dissipate up to 1 W continuously at 25 °C ambient when properly heatsinked via its drain lead. Its R_DS(on) variation with temperature is well-characterized for precision biasing.

What is the thermal resistance of BSN254, and how should it be mounted?

The BSN254 has a junction-to-ambient thermal resistance (R_{th j-a}) of 125 K/W when mounted on a PCB with a minimum 10 × 10 mm copper pad on the drain lead and lead lengths ≤4 mm. To achieve rated 1 W power dissipation, the drain must be soldered to this thermal pad; using smaller pads or longer leads increases thermal resistance and reduces safe operating current. The BSN254's TO-92 outline requires through-hole mounting with axial lead orientation.

How does BSN254 differ from BSN254A in practical circuit design?

The BSN254 and BSN254A share identical electrical specifications but feature opposite pinouts in the SOT54 package: BSN254 uses Gate-Drain-Source (pins 1–2–3), while BSN254A uses Source-Gate-Drain. This means BSN254A cannot be substituted into a BSN254-designed PCB without trace rerouting. The BSN254 is optimized for low-side switching with gate-referenced control; BSN254A suits high-side or source-follower configurations where source is grounded.