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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Single Bipolar Transistors

onsemi MPSA18_D74Z

Name: MPSA18_D74Z
Brand: onsemi
SKU: MPSA18_D74Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MPSA18_D74Z

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Datasheet:: MPSA18_D74Z.pdf

Description:: TRANS NPN 45V 0.1A TO-92-3

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Product details

Overview

MPSA18_D74Z from Fairchild Semiconductor is an NPN general-purpose amplifier transistor optimized for low-noise, high-gain signal amplification at collector currents from 1 µA to 50 mA. It features V_CEO = 45 V, h_FE = 500–1500 (at I_C = 1–10 mA), f_T = 100 MHz, NF = 1.5 dB, and TO-92 radial ammo packaging (EOL code D74Z). It is used in audio preamplifier stages and sensor interface circuits.

For engineers reviewing the MPSA18_D74Z datasheet, pinout, applications, or equivalent options, key selection criteria include verified low-noise performance at microamp bias, guaranteed h_FE minimum across operating current range, thermal resistance (R_θJA = 200 °C/W), TO-92 mechanical compatibility, and EOL-specific tape-and-reel configuration (D74Z = radial ammo, flat-on-top, collector-first lead orientation).

Technical Context

The MPSA18_D74Z implements a silicon planar epitaxial NPN structure with process-controlled base width to achieve high current gain and low noise figure. Its design targets linear small-signal amplification rather than switching, evidenced by specified f_T, C_cb = 3.0 pF, and NF = 1.5 dB at 1 kHz.

It operates within a junction temperature range of –55°C to +150°C and is rated for continuous collector current up to 100 mA with P_D = 625 mW at 25°C. Derating is required above 25°C at 5.0 mW/°C, consistent with its TO-92 package thermal characteristics (R_θJC = 83.3 °C/W, R_θJA = 200 °C/W).

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown under open-base conditions; defines usable supply headroom in amplifier designs.
h_FE	500–1500 - DC current gain range at V_CE = 5 V and I_C = 1–10 mA; enables stable biasing in common-emitter configurations without excessive base drive.
f_T	100 MHz - Unity-gain bandwidth; supports audio and low-RF amplification up to ~10 MHz with usable gain margin.
NF	1.5 dB - Noise figure at V_CE = 5 V, I_C = 100 µA, R_S = 10 kΩ, 1 kHz; confirms suitability for low-level signal amplification where SNR preservation is critical.
P_D	625 mW - Maximum steady-state power dissipation at 25°C; sets thermal limits for PCB layout and heatsinking in linear operation.
C_cb	3.0 pF - Collector-base capacitance at V_CB = 5 V, 1 MHz; contributes to Miller effect and high-frequency roll-off; enables stability analysis in feedback amplifier designs.

Pinout & Package

Package: TO-92 radial ammo (EOL code D74Z), with flat side oriented upward and collector as the first lead exiting the package. Lead configuration follows standard TO-92 pinout: Emitter (lead 1), Base (lead 2), Collector (lead 3) when viewed with flat side facing outward and leads downward.

Pin/Terminal	Circuit Role	Design Meaning
Lead 1 (Emitter)	Current sink terminal	Reference node for bias network; connects to ground or emitter degeneration resistor in common-emitter topology.
Lead 2 (Base)	Control input terminal	Receives base current to modulate collector current; requires impedance-matched drive for low-noise operation.
Lead 3 (Collector)	Current source terminal	Delivers amplified output current; connects to load resistor or next stage; voltage swing limited by V_CEO rating.

Key Features

Feature	Design Value
Low-noise amplification	NF = 1.5 dB at 1 kHz enables high-fidelity signal recovery in microphone preamps and sensor front-ends.
High DC current gain	h_FE ≥ 500 at I_C = 1 mA ensures stable bias point with minimal base current variation across unit-to-unit spread.
Wide gain-bandwidth product	f_T = 100 MHz supports broadband analog signal conditioning up to mid-audio frequencies with predictable phase response.
Robust thermal rating	Junction temperature range of –55°C to +150°C allows deployment in industrial and automotive under-hood environments.

Applications

Audio Preamplifier Stage	Temperature Sensor Interface
Use Scenario: Amplifying weak signals from electret microphones or magnetic pickups prior to ADC sampling. IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration. Use Value: Low NF (1.5 dB) and high h_FE preserve signal integrity and reduce required gain staging, minimizing total system noise floor.	Use Scenario: Linear amplification of millivolt-level outputs from thermistor or RTD bridge circuits. IC Role / Device Role / Timing Role: Transconductance amplifier converting resistance change into proportional voltage swing. Use Value: Stable h_FE across 1–10 mA ensures repeatable gain calibration; low V_CE(sat) (0.2 V) maintains linearity over wide temperature range.
RF Detector Front-End	Low-Power Oscillator Core
Use Scenario: First-stage amplification in AM/FM receiver IF strips or crystal detector buffers. IC Role / Device Role / Timing Role: High-f_T (100 MHz) NPN active device in tuned amplifier or cascode configuration. Use Value: C_cb = 3.0 pF and f_T = 100 MHz enable stable gain up to 10–20 MHz with controlled bandwidth and minimal parasitic resonance.	Use Scenario: Active element in Colpitts or Hartley oscillator designs for clock generation in low-power embedded systems. IC Role / Device Role / Timing Role: Gain block sustaining oscillation at fundamental frequency via positive feedback. Use Value: Verified f_T and low C_eb (6.5 pF) support reliable startup and frequency stability at 1–10 MHz without external compensation.

Audio Preamplifier Stage

Temperature Sensor Interface

Use Scenario: Amplifying weak signals from electret microphones or magnetic pickups prior to ADC sampling.

IC Role / Device Role / Timing Role: NPN small-signal amplifier in common-emitter configuration with emitter degeneration.

Use Value: Low NF (1.5 dB) and high h_FE preserve signal integrity and reduce required gain staging, minimizing total system noise floor.

Use Scenario: Linear amplification of millivolt-level outputs from thermistor or RTD bridge circuits.

IC Role / Device Role / Timing Role: Transconductance amplifier converting resistance change into proportional voltage swing.

Use Value: Stable h_FE across 1–10 mA ensures repeatable gain calibration; low V_CE(sat) (0.2 V) maintains linearity over wide temperature range.

RF Detector Front-End

Low-Power Oscillator Core

Use Scenario: First-stage amplification in AM/FM receiver IF strips or crystal detector buffers.

IC Role / Device Role / Timing Role: High-f_T (100 MHz) NPN active device in tuned amplifier or cascode configuration.

Use Value: C_cb = 3.0 pF and f_T = 100 MHz enable stable gain up to 10–20 MHz with controlled bandwidth and minimal parasitic resonance.

Use Scenario: Active element in Colpitts or Hartley oscillator designs for clock generation in low-power embedded systems.

IC Role / Device Role / Timing Role: Gain block sustaining oscillation at fundamental frequency via positive feedback.

Use Value: Verified f_T and low C_eb (6.5 pF) support reliable startup and frequency stability at 1–10 MHz without external compensation.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N5088	Identical electrical specs per Fairchild documentation; same Process 07, same V_CEO/h_FE/NF/f_T ratings.	No functional difference; used interchangeably in low-noise preamp designs.	Select 2N5088 only if D74Z packaging is unavailable; identical performance but different EOL marking and reel format.
BC549C	Lower V_CEO (30 V vs. 45 V); h_FE min = 420 (vs. 500); NF = 4 dB (vs. 1.5 dB); f_T = 300 MHz (higher but noisier).	Less suitable for high-SNR, high-headroom applications; better for general-purpose switching or higher-frequency non-critical gain.	Choose BC549C only when lower voltage operation and relaxed noise requirements apply; not drop-in for MPSA18_D74Z in audio-sensitive designs.

Compared with 2N5088 and BC549C, the MPSA18_D74Z delivers superior noise performance and higher voltage tolerance while maintaining proven reliability in TO-92 radial ammo form factor-critical for automated assembly of precision analog boards requiring traceable, low-variation gain devices.

Availability

MPSA18_D74Z is available at Aetrix Electronics and suitable for audio preamplifiers, sensor signal conditioning, and RF detector front-ends requiring stable component supply, consistent h_FE distribution, and low-noise transistor performance.

Supply support for MPSA18_D74Z 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 MPSA18_D74Z belongs to Fairchild's legacy NPN general-purpose amplifier family, designed specifically for low-noise, high-gain linear amplification in consumer, industrial, and instrumentation applications where signal fidelity and bias stability are essential.

FAQ

What is the pin configuration of the MPSA18_D74Z?

The MPSA18_D74Z uses standard TO-92 pinout: when viewed with the flat side facing outward and leads pointing down, Lead 1 is Emitter, Lead 2 is Base, and Lead 3 is Collector. This matches EOL code D74Z specification: radial ammo packaging with flat-on-top orientation and collector-first lead exit.

Does the MPSA18_D74Z meet RoHS requirements?

Yes, the MPSA18_D74Z complies with RoHS Directive 2011/65/EU. Fairchild's TO-92 devices manufactured after 2006-including MPSA18_D74Z-are lead-free, with matte tin-plated leads and halogen-free molding compound, as confirmed in Fairchild's official compliance documentation and packaging labels.

What is the maximum safe operating collector current for the MPSA18_D74Z?

The MPSA18_D74Z has an absolute maximum continuous collector current (I_C) rating of 100 mA. However, for reliable linear amplification, operation is recommended between 1 µA and 50 mA per datasheet guidance-exceeding 50 mA risks gain compression and increased noise without thermal derating.

How does the noise figure of the MPSA18_D74Z compare to other TO-92 NPN transistors?

The MPSA18_D74Z achieves NF = 1.5 dB at 1 kHz, which is among the lowest for TO-92 packaged NPN transistors. For comparison, BC549C specifies NF = 4 dB and PN2222A specifies NF ≈ 10 dB under similar conditions-making MPSA18_D74Z preferred for ultra-low-noise front-end stages.

Is the MPSA18_D74Z suitable for switching applications?

The MPSA18_D74Z is not optimized for switching-it lacks fast turn-off characteristics, has relatively high C_eb (6.5 pF), and is characterized for linear gain and noise, not saturation voltage or storage time. While it can switch at low frequencies (<100 kHz), dedicated switching transistors like PN2222A or MMBT2222 offer better V_CE(sat) and speed for digital logic interfaces.

MPSA18_D74Z Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA) Formed Leads

Packaging:: Tape & Box (TB)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 100 mA

Voltage - Collector Emitter Breakdown (Max):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 300mV @ 5mA, 50mA

Current - Collector Cutoff (Max):: 50nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 500 @ 10mA, 5V

Power - Max:: 625 mW

Frequency - Transition:: 100MHz

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

MPSA18_D74Z FAQ

1.How can I place an order for MPSA18_D74Z through Aetrix?

Please submit a Request for Quotation (RFQ) for MPSA18_D74Z on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for MPSA18_D74Z reliable?

The price and inventory of MPSA18_D74Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MPSA18_D74Z is usually 5 days.

3.What payment methods are accepted for MPSA18_D74Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MPSA18_D74Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MPSA18_D74Z?

MPSA18_D74Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MPSA18_D74Z order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for MPSA18_D74Z?

For technical support, including MPSA18_D74Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MPSA18_D74Z requirements.

6.How does Aetrix verify that MPSA18_D74Z is sourced from the original manufacturer or authorized distributors?

All MPSA18_D74Z products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MPSA18_D74Z meets industry standards.

7.What is the process for return or replacement of MPSA18_D74Z?

All MPSA18_D74Z units undergo pre-shipment inspection (PSI). If there is an issue with MPSA18_D74Z, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The MPSA18_D74Z part is unused and in its original packaging.

Return procedure for MPSA18_D74Z:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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