onsemi MPSA42RLRP

Overview

MPSA42RLRP from onsemi is an NPN silicon high-voltage transistor designed for switching and amplification in off-line power supplies, relay drivers, and HV interface circuits. It supports 300 V_CEO, 500 mA continuous collector current, 625 mW ambient-rated dissipation, and delivers DC current gain (h_FE) ≥25 at 1 mA, with f_T = 50 MHz.

For engineers reviewing the MPSA42RLRP datasheet, pinout, applications, or equivalent options, key selection criteria include its 300 V breakdown rating, TO-92 package thermal limits, saturation voltage under 0.5 V at I_C/I_B = 10, and compatibility with high-impedance base drive in flyback snubber or HV logic-level translation.

Technical Context

The MPSA42RLRP operates as a general-purpose NPN bipolar junction transistor optimized for high-voltage switching where V_CEO ≥ 300 V and moderate speed (f_T = 50 MHz) are required. Its low C_cb of 3.0 pF at 20 V enables reduced Miller feedback in fast-switching topologies.

It features a fixed lead configuration (Emitter–Collector–Base, Style 14), specified thermal resistance R_JA = 200 °C/mW, and guaranteed V_CE(sat) ≤ 0.5 V at I_C = 20 mA / I_B = 2 mA - critical for minimizing conduction loss in discrete HV switch stages.

Key Specifications

Pinout & Package

Package: TO-92 (Case 29-11), molded plastic with 3 leads; standardized for manual insertion and wave soldering. Dimensions comply with ANSI Y14.5M; lead pitch 2.54 mm (0.100"), body height 4.45–5.20 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage NPN transistor applications.

Compared with BC639 and MPSA92, the MPSA42RLRP uniquely balances 300 V capability, predictable low-current gain, and industry-standard TO-92 packaging - making it the preferred choice for cost-sensitive, space-constrained HV switching where voltage margin is non-negotiable.

Availability

MPSA42RLRP is available at Aetrix Electronics and suitable for off-line auxiliary power supplies, relay driver interfaces, snubber circuit switches, and high-voltage logic-level translation requiring stable component supply and long-term manufacturability.

Supply support for MPSA42RLRP 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient innovation across automotive, industrial, cloud, and intelligent edge applications.

The MPSA42RLRP belongs to onsemi's Preferred Devices family of general-purpose bipolar transistors engineered for reliability, consistency, and broad compatibility in high-voltage discrete switching and amplification roles.

FAQ

What is the maximum collector-emitter voltage rating for MPSA42RLRP?

The MPSA42RLRP has a guaranteed minimum V_CEO rating of 300 Vdc under test conditions (I_C = 1.0 mA, I_B = 0). This allows safe operation in circuits where collector potentials reach up to 300 V relative to the emitter, such as in 230 VAC-derived auxiliary supplies. Derating is required above 25°C ambient per the 5.0 mW/°C thermal derating curve.

Is MPSA42RLRP pin-compatible with MPSA43?

No, the MPSA42RLRP and MPSA43 share identical TO-92 packaging and pinout (Style 14: Emitter–Collector–Base), but they differ electrically - MPSA43 has V_CEO = 200 V and V_CBO = 200 V versus 300 V for MPSA42RLRP. Substituting MPSA43 for MPSA42RLRP risks overvoltage failure in 250–300 V applications.

What is the typical DC current gain (h_FE) of MPSA42RLRP at 10 mA collector current?

Per the onsemi datasheet, the MPSA42RLRP exhibits h_FE ≥40 at I_C = 10 mA, V_CE = 10 V, and T_A = 25°C. This value supports robust saturation with modest base drive - for example, 250 µA base current yields ≥10 mA collector current, enabling efficient use in microcontroller-driven HV interfaces.

Does MPSA42RLRP have a Pb-free version?

Yes, the Pb-free variant is designated MPSA42RLRPG and shares identical electrical and mechanical specifications with MPSA42RLRP. It complies with RoHS Directive 2011/65/EU and uses matte tin lead finish. Both variants are supplied in 2000-unit ammo packs and are functionally interchangeable in new designs.

What is the thermal resistance junction-to-ambient (R_JA) for MPSA42RLRP in standard TO-92 mounting?

The MPSA42RLRP has a specified R_JA of 200 °C/mW when mounted on a standard FR-4 PCB with minimal copper area. This means a 300 mW power dissipation raises junction temperature by 60°C above ambient. For sustained operation >200 mW, additional copper pour or heatsinking is recommended to maintain T_J ≤ 150°C.