onsemi MPSA27

Overview

MPSA27 from Fairchild Semiconductor is an NPN general-purpose amplifier transistor designed for high-current-gain linear amplification and switching up to 500mA collector current. It features a 60V V_CEO, 800mA I_C continuous rating, 10,000 minimum h_FE at 10mA, 125MHz f_T, and TO-92 package - used in low-frequency audio preamplifiers, relay drivers, and signal buffering stages.

For engineers reviewing the MPSA27 datasheet, pinout, applications, or equivalent options, key selection considerations include its ultra-high DC current gain at moderate currents, saturation voltage under defined drive conditions, thermal resistance in FR-4 mounting, and compatibility with legacy through-hole PCB layouts requiring TO-92 footprint.

Technical Context

The MPSA27 operates as a silicon NPN bipolar junction transistor optimized for linear amplification where high h_FE (>10,000 at 10mA) reduces required base drive and improves signal fidelity in low-noise analog stages. Its 60V breakdown ratings (V_CEO, V_CBO) support operation in 24–48V industrial control rails.

Thermal design relies on its 200°C/W R_θJA on standard FR-4 (36mm × 18mm), limiting usable power dissipation to ~625mW at 25°C ambient; derating is 5.0mW/°C above that temperature. The device is not rated for RF power amplification but supports small-signal bandwidth up to 125MHz at 10mA bias.

Key Specifications

Pinout & Package

Package: TO-92 (3-lead plastic through-hole). Standard lead configuration: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector - verified per Fairchild Rev. A1 datasheet mechanical drawing and terminal assignment table.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN amplifier applications.

Compared with MPSA18 and BC547B, the MPSA27 delivers uniquely high DC current gain at moderate collector currents - making it irreplaceable in precision analog buffering and low-distortion preamplifier designs where base drive minimization and linearity are critical.

Availability

MPSA27 is available at Aetrix Electronics and suitable for audio preamplifiers, relay driver circuits, and sensor signal buffers requiring stable component supply across industrial control, test equipment, and legacy repair programs.

Supply support for MPSA27 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The MPSA27 belongs to Fairchild's legacy general-purpose bipolar transistor family, engineered specifically for high-gain linear amplification and medium-current switching in industrial and instrumentation applications.

FAQ

What is the maximum collector-emitter voltage rating for the MPSA27?

The MPSA27 has a guaranteed minimum V_CEO (collector-emitter breakdown voltage) of 60 V at I_C = 100 µA and V_BE = 0. This rating applies under steady-state DC conditions at 25°C ambient and defines the absolute upper limit for safe operation in amplifier or switch configurations. Exceeding this voltage risks irreversible junction breakdown. The MPSA27 must be operated within this limit in all designs.

Does the MPSA27 have a documented pinout configuration for TO-92 packaging?

Yes, the MPSA27 uses the standard TO-92 pinout: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector - explicitly confirmed in the Fairchild Rev. A1 datasheet mechanical drawings and terminal assignment table. This matches industry-standard orientation when viewing the flat side of the package with leads pointing downward and left-to-right numbering.

What is the minimum DC current gain (h_FE) of the MPSA27 at 10mA collector current?

The MPSA27 guarantees a minimum h_FE of 10,000 at I_C = 10 mA and V_CE = 5.0 V, as specified in the "On Characteristics" table of the Fairchild datasheet. This ultra-high gain is a defining feature distinguishing it from standard general-purpose transistors like BC547 or MPSA18, and directly enables low-base-drive analog amplifier designs.

Can the MPSA27 be used in switching applications, and what is its saturation voltage?

Yes, the MPSA27 is suitable for medium-speed switching applications. Its V_CE(sat) is specified at 1.5 V when I_C = 100 mA and I_B = 0.1 mA - indicating reliable saturation under controlled base drive. However, due to its high h_FE, careful base resistor selection is required to avoid excessive stored charge and slow turn-off. The MPSA27 remains effective in relay drivers and LED switches up to ~10kHz.

Is the MPSA27 RoHS compliant and lead-free?

The original Fairchild MPSA27 (Rev. A1, June 2002) predates mandatory RoHS implementation and was manufactured as a leaded device. Current Aetrix Electronics inventory consists of RoHS-compliant, lead-free reprocessed or second-source equivalents fully qualified to JEDEC J-STD-020 moisture sensitivity and solderability standards - with full compliance documentation available upon request for the MPSA27.