onsemi MPSA18RLRM

Overview

MPSA18RLRM from onsemi is an NPN silicon low-noise general-purpose transistor in TO-92 package, rated for V_CEO = 45 V, I_C = 200 mA, and P_D = 625 mW at T_A = 25°C, with h_FE up to 1500 at I_C = 10 mA and f_T = 100–160 MHz - used in audio preamplifier stages, RF amplifier input stages, and low-noise sensor signal conditioning circuits.

For engineers reviewing the MPSA18RLRM datasheet, pinout, applications, or equivalent options, key selection criteria include its low noise figure (NF = 0.5 dB at I_C = 100 µA, R_S = 10 kΩ, f = 1 kHz), high DC current gain, TO-92 mechanical compatibility, and Pb-free availability in ammo pack format.

Technical Context

The MPSA18RLRM operates as a discrete NPN bipolar junction transistor optimized for low-noise amplification in small-signal analog circuits. Its design emphasizes high h_FE (min 400 at I_C = 10 mA), low V_CE(sat) (max 0.3 V at I_C = 50 mA), and low noise voltage (e_n = 6.5 nV/√Hz at I_C = 100 µA).

It features V_(BR)CEO = 45 V, V_EBO = 6.5 V, and C_cb = 1.7–3.0 pF, supporting stable operation in high-gain, medium-frequency (<160 MHz f_T) linear amplifier topologies where thermal resistance (R_JA = 200 °C/W) and junction temperature limits (−55 to +150 °C) are critical.

Key Specifications

Pinout & Package

Package: TO-92 (Case 29-11, Style 1), 3-lead through-hole plastic package with standard lead spacing (P = 2.54 mm). Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise NPN transistor applications.

Compared with BC549C and 2N5089, the MPSA18RLRM offers the best balance of 45 V rating, sub-0.5 dB noise, and industry-standard TO-92 footprint - making it ideal for cost-sensitive, high-volume audio and RF front-end designs where both voltage margin and noise performance are constrained.

Availability

MPSA18RLRM is available at Aetrix Electronics and suitable for audio preamplifier stages, RF signal amplifiers, and low-noise sensor interface circuits requiring stable component supply, consistent parametric performance, and RoHS-compliant through-hole packaging.

Supply support for MPSA18RLRM 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 manufacturer specializing in energy-efficient power, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The MPSA18RLRM belongs to onsemi's legacy low-noise bipolar transistor product line, designed specifically for high-fidelity analog signal amplification in cost-sensitive, high-reliability discrete circuit applications.

FAQ

What is the maximum collector-emitter voltage rating for the MPSA18RLRM?

The MPSA18RLRM has a maximum collector-emitter voltage rating (V_(BR)CEO) of 45 Vdc, tested at I_C = 10 mA with base open. This rating defines the absolute upper limit for voltage applied between collector and emitter in normal operation and must not be exceeded to avoid device breakdown or permanent damage.

Is the MPSA18RLRM RoHS compliant?

Yes, the MPSA18RLRM is RoHS compliant and lead-free. Its Pb-free variant is designated MPSA18RLRMG, also in TO-92 package and 2000-unit ammo pack shipping format. Both versions meet EU Directive 2011/65/EU requirements without performance derating.

What is the typical noise figure of the MPSA18RLRM and under what conditions is it measured?

The typical noise figure (NF) of the MPSA18RLRM is 0.5 dB, measured at I_C = 100 µA, V_CE = 5.0 Vdc, R_S = 10 kΩ, and f = 1.0 kHz. This value reflects its optimized low-noise performance in high-impedance, low-current small-signal amplification applications such as microphone preamplifiers.

How does the DC current gain (h_FE) of the MPSA18RLRM vary with collector current?

The MPSA18RLRM exhibits h_FE = 400 (min) at I_C = 10 mA, rising to 1500 (max) at I_C = 10 mA under typical conditions. At lower currents (I_C = 1.0 mA), h_FE remains ≥500, and at higher currents (I_C = 100 mA), it drops to ≥500 - confirming strong gain consistency across its operational range.

What is the thermal resistance (R_JA) of the MPSA18RLRM and how does it affect PCB layout?

The MPSA18RLRM has a thermal resistance R_JA of 200 °C/W when soldered to a standard PCB per JEDEC standards. To maintain T_J < 125 °C at full 625 mW dissipation, at least 1.5 cm² of 1-oz copper pour connected to the collector lead is recommended - underscoring the need for intentional thermal relief in high-duty-cycle designs.