onsemi MPSA44

Overview

MPSA44 from onsemi is an NPN silicon high-voltage general-purpose transistor in TO-92 package, rated for 400 V_CEO, 300 mA continuous collector current, and 625 mW power dissipation at 25°C ambient. It delivers DC current gain (h_FE) of 40–200 across 1–100 mA I_C, with V_CE(sat) ≤ 0.75 V at I_C/I_B = 10, enabling use in high-voltage switching and linear amplification circuits such as CRT flyback drivers and industrial relay interfaces.

For engineers reviewing the MPSA44 datasheet, pinout, applications, or equivalent options, key selection criteria include its 400 V breakdown rating, TO-92 thermal resistance (R_JA = 200°C/W), verified h_FE vs. I_C curves, safe operating area up to 150°C junction temperature, and Pb-free RLRAG tape-and-reel packaging compliance.

Technical Context

The MPSA44 operates as a discrete NPN bipolar junction transistor optimized for high-voltage switching applications where V_CEO ≥ 400 V and moderate current handling are required. Its structure supports stable DC gain across I_C = 1–100 mA at V_CE = 10 V, with saturation behavior characterized by V_BE(sat) ≤ 0.75 V and V_CE(sat) ≤ 0.75 V under defined drive conditions.

Thermal design is constrained by R_JA = 200°C/W and R_JC = 83.3°C/W, requiring careful PCB copper area planning for ambient operation above 25°C. The device exhibits C_ibo = 130 pF and C_obo = 7.0 pF at specified bias points, limiting usable bandwidth in RF-coupled or fast-switching configurations.

Key Specifications

Pinout & Package

Package: TO-92 (Case 29-11, Style 1), molded plastic with 3 leads. Standard lead configuration: Emitter (Pin 1), Base (Pin 2), Collector (Pin 3).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BCP56-10T1G and 2N5551, the MPSA44 uniquely satisfies 400 V switching requirements in through-hole form factor while maintaining industry-standard TO-92 thermal and gain characteristics-making it irreplaceable in legacy CRT, HV power supply, and surge-tolerant sensing applications.

Availability

MPSA44 is available at Aetrix Electronics and suitable for industrial relay drivers, CRT flyback circuits, AC line voltage sensing, and high-voltage logic level shifting requiring stable component supply and long-term manufacturability.

Supply support for MPSA44 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 specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The MPSA44 belongs to onsemi's legacy high-voltage discrete transistor family, designed specifically for reliability-critical analog and switching functions in consumer electronics, industrial controls, and test equipment where 400 V standoff and TO-92 serviceability are essential.

FAQ

What is the maximum collector-emitter voltage rating for the MPSA44?

The MPSA44 has a guaranteed minimum V_(BR)CEO of 400 Vdc at I_C = 1.0 mAdc and I_B = 0. This rating is confirmed in the "OFF CHARACTERISTICS" table of the official onsemi datasheet (Publication Order Number: MPSA44/D, Rev. 4). Exceeding this voltage risks avalanche breakdown and permanent device failure. The MPSA44 is therefore suited for circuits where transient or steady-state voltages reach up to 400 V, such as flyback transformer primaries and relay coil suppression networks.

Is the MPSA44RLRAG variant RoHS-compliant and lead-free?

Yes, the MPSA44RLRAG carries the "G" suffix per onsemi's ordering nomenclature, indicating Pb-free construction and RoHS compliance. This is explicitly stated in the "ORDERING INFORMATION" section of the datasheet, which lists "MPSA44RLRAG" as a TO-92 Pb-Free package shipped in tape-and-reel format (2000 units). The device meets JEDEC J-STD-020 moisture sensitivity level 1 and supports standard reflow profiles without lead contamination concerns.

What is the typical DC current gain (h_FE) of the MPSA44 at 10 mA collector current?

At I_C = 10 mAdc and V_CE = 10 Vdc, the MPSA44 exhibits a minimum h_FE of 50 and a maximum of 200, as documented in the "ELECTRICAL CHARACTERISTICS" table. This wide gain spread reflects process variation across production lots and necessitates design margining-especially in linear amplifier configurations. The MPSA44 datasheet Figure 1 further confirms this range across temperature, showing h_FE retention down to −55°C and up to +125°C.

Can the MPSA44 be used in switching applications above 100 kHz?

The MPSA44 is not optimized for high-frequency switching above 100 kHz. Its small-signal current gain |h_fe| drops to unity near 100 MHz (per Figure 6), and measured turn-off time t_f exceeds 1 µs under typical test conditions (Figure 8). For reliable operation, the MPSA44 should be limited to ≤50 kHz in hard-switched topologies. Its primary strength lies in lower-frequency, high-voltage applications like CRT deflection and relay driving-not RF or resonant converter stages.

What thermal derating applies to the MPSA44 when ambient temperature exceeds 25°C?

The MPSA44's total device dissipation must be derated linearly at 5.0 mW/°C above T_A = 25°C when mounted on a standard FR-4 PCB with no added copper heatsinking. This is derived from the "MAXIMUM RATINGS" table, where PD = 625 mW at 25°C and the derate factor is explicitly listed as 5.0 mW/°C. At 75°C ambient, for example, allowable power drops to 625 mW − (50°C × 5.0 mW/°C) = 375 mW. The MPSA44's R_JA = 200°C/W confirms this relationship.