onsemi MPSA28

Overview

MPSA28 from onsemi is an NPN silicon Darlington transistor in TO-92 package, rated for 80 V_CEO, 500 mA continuous collector current, and 625 mW power dissipation at 25°C ambient. It delivers high DC current gain (h_FE ≥ 10,000 at I_C = 10 mA), low V_CE(sat) (≤ 0.7 V), and operates across −55°C to +150°C junction temperature range - commonly used in low-speed switching, relay drivers, and signal amplification stages.

For engineers reviewing the MPSA28 datasheet, pinout, applications, or equivalent options, key selection considerations include its Darlington configuration enabling high current drive with minimal base current, Pb-free TO-92 packaging, thermal resistance (R_JA = 200°C/W), and compatibility with legacy through-hole board layouts requiring discrete high-gain switching.

Technical Context

The MPSA28 integrates two cascaded NPN transistors in a monolithic Darlington pair, delivering ultra-high current gain without external biasing components. Its structure supports low-input-current switching while maintaining defined saturation voltage and breakdown limits (V_CEO = 80 V, V_CBO = 80 V, V_EBO = 12 V).

Designed for linear and switching operation in DC-coupled circuits, it exhibits f_T = 125 MHz at I_C = 10 mA and shows stable h_FE over −55°C to +150°C. C_obo = 5.0 pF ensures minimal capacitive loading in high-impedance node interfaces.

Key Specifications

Pinout & Package

Package: TO-92 (Case 29-11), 3-lead through-hole plastic package with standard lead spacing and E-B-C pinout orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington transistor applications.

Compared with ULN2003A and MPSA13, the MPSA28 provides optimal balance of single-device simplicity, 80 V rating, and ultra-low base drive requirement - making it preferred for cost-sensitive, low-channel-count relay or LED driver designs where discrete placement and thermal management are prioritized.

Availability

MPSA28 is available at Aetrix Electronics and suitable for relay driver circuits, LED current amplifiers, industrial sensor interfaces, and legacy logic level shifter designs requiring stable component supply and long-term manufacturability.

Supply support for MPSA28 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 for automotive, industrial, cloud, medical, and IoT applications.

The MPSA28 belongs to onsemi's legacy discrete bipolar transistor product line, engineered for robustness, wide temperature operation, and seamless integration into cost-sensitive, high-reliability through-hole systems.

FAQ

What is the maximum collector-emitter voltage rating for the MPSA28?

The MPSA28 has a maximum collector-emitter voltage (V_CEO) rating of 80 Vdc, verified per the official onsemi datasheet MPSA28/D Rev. 2. This value defines the absolute upper limit for voltage applied between collector and emitter with base open. Exceeding this rating risks irreversible avalanche breakdown. The MPSA28 must be operated within this limit in all applications, including inductive load switching where voltage spikes may occur.

Is the MPSA28 available in a Pb-free package?

Yes, the MPSA28RLRPG variant is explicitly designated as Pb-free and RoHS-compliant in the onsemi datasheet. It uses the same TO-92 package as the standard MPSA28 but replaces leaded solder with lead-free termination. The MPSA28RLRPG maintains identical electrical specifications and thermal characteristics, ensuring drop-in compatibility in environmentally regulated manufacturing environments without redesign.

What is the typical DC current gain (h_FE) of the MPSA28 at 10 mA collector current?

The MPSA28 guarantees a minimum DC current gain (h_FE) of 10,000 at I_C = 10 mA and V_CE = 5.0 Vdc, as specified in the "ON CHARACTERISTICS" table of the official MPSA28/D datasheet. This high gain enables microampere-level base drive, making the MPSA28 especially suitable for interfacing with low-output-current sources such as microcontroller GPIO pins or CMOS logic outputs without additional amplification stages.

Can the MPSA28 replace the MPSA29 in existing designs?

The MPSA28 and MPSA29 share identical pinout, package, and gain characteristics but differ in voltage ratings: MPSA28 is rated for 80 V_CEO, while MPSA29 is rated for 100 V_CEO. Substituting MPSA28 for MPSA29 is acceptable only if the application's maximum collector-emitter voltage remains below 80 V. Using MPSA28 in a 100 V circuit risks premature failure. Always verify operating voltage margins before interchange.

What is the thermal resistance junction-to-ambient (R_JA) for the MPSA28 in TO-92 package?

The thermal resistance junction-to-ambient (R_JA) for the MPSA28 in TO-92 package is 200°C/W, as published in the "THERMAL CHARACTERISTICS" section of the MPSA28/D datasheet. This value applies under standard JEDEC test conditions (still air, no heatsink). For continuous 500 mA operation, ambient temperature must be limited to ≤25°C or derated accordingly - e.g., at 50°C ambient, maximum allowable power dissipation drops to 525 mW.