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

onsemi MPSA20G

Name: MPSA20G
Brand: onsemi
SKU: MPSA20G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MPSA20G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body

Datasheet:: MPSA20G.pdf

Description:: TRANS NPN 40V 0.1A TO92

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MPSA20G from onsemi is an NPN silicon general-purpose amplifier transistor in a Pb-free TO-92 package, rated for 40 V_CEO, 100 mA continuous collector current, and 625 mW power dissipation at 25°C ambient - commonly used in low-noise preamplifier stages, signal buffering, and discrete gain blocks in audio and sensor interface circuits.

For engineers reviewing the MPSA20G datasheet, pinout, applications, or equivalent options, key selection criteria include its 40–400 DC current gain (h_FE) at 5 mA/10 V, 125 MHz f_T, low 4.0 pF C_obo, and verified noise performance down to 1.0 dB NF at 1 kHz with R_S = 1 kΩ - critical for analog front-end design where gain stability and signal integrity are prioritized.

Technical Context

The MPSA20G operates as a linear NPN bipolar junction transistor optimized for small-signal amplification rather than switching. Its h_FE spans 40–400 across 1–100 mA collector currents, with V_CE(sat) ≤ 0.25 V at I_C/I_B = 10, supporting reliable active-region biasing in Class-A configurations.

Thermal performance is defined by R_JA = 200°C/W (PCB-mounted) and R_JC = 83.3°C/W, enabling operation from −55°C to +150°C junction temperature. Noise characteristics are characterized at V_CE = 5 V, I_C = 1 mA, with en ≈ 3.0 nV/√Hz and In ≈ 30 pA/√Hz at 1 kHz - confirming suitability for low-level analog signal conditioning.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	40 V - Maximum safe collector-emitter voltage before breakdown; sets upper rail limit for single-supply amplifier stages.
I_C (continuous)	100 mA - Sustained collector current capability; supports medium-gain, low-power analog gain blocks.
h_FE	40–400 - Wide DC current gain range at 5 mA/10 V; enables flexible bias design but requires emitter degeneration for stability.
f_T	125 MHz - Unity-gain bandwidth; ensures usable gain up to ~10–20 MHz in practical CE configurations.
C_obo	4.0 pF - Output capacitance at 10 V reverse bias; limits high-frequency roll-off and affects Miller compensation requirements.
NF (1 kHz)	≤ 3.0 dB at R_S = 1 kΩ - Verified low-noise figure; suitable for microphone preamps and sensor signal chains.
P_D @ T_A = 25°C	625 mW - Thermal derating starts at 5.0 mW/°C above 25°C; constrains maximum dissipation in enclosed environments.

Pinout & Package

Package: TO-92 (Case 29-11), Pb-free, through-hole mounting. Standard lead configuration with Emitter (Pin 1), Base (Pin 2), Collector (Pin 3).

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Connected to ground or emitter resistor in common-emitter amplifiers; sets DC bias point and influences input impedance.
2 (Base)	Control input node	Receives base drive current; requires current-limiting resistor or voltage divider for stable biasing due to β variability.
3 (Collector)	Output current source	Delivers amplified output current; connects to load resistor or next stage; polarity defines NPN active-mode operation.

Key Features

Feature	Design Value
Low-noise amplification	Verified 1.0–3.0 dB noise figure at 1 kHz with R_S = 1 kΩ - enables high-fidelity signal recovery in sensor interfaces.
Wide h_FE range	40–400 at I_C = 5 mA - accommodates production spread but mandates emitter degeneration for predictable gain.
High f_T	125 MHz - supports broadband small-signal amplification up to 20 MHz without significant gain loss.
Pb-free TO-92 packaging	RoHS-compliant construction with standard through-hole footprint - simplifies legacy PCB assembly and rework.
Robust thermal rating	T_J = −55°C to +150°C - ensures reliability in industrial and automotive under-hood auxiliary circuits.

Applications

Audio Preamp Stage	Sensor Signal Conditioning
Use Scenario: Amplifying low-level microphone or piezoelectric sensor outputs prior to ADC sampling. IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier in common-emitter topology with emitter degeneration. Use Value: Delivers stable 20–40 dB voltage gain with <3.0 dB noise figure at 1 kHz, preserving SNR in battery-powered recorders.	Use Scenario: Boosting weak signals from thermistors, photodiodes, or strain gauges in measurement front-ends. IC Role / Device Role / Timing Role: Linear small-signal gain block with DC-coupled biasing and low input-referred noise. Use Value: Enables sub-mV signal resolution with minimal added noise, critical for 12–16-bit precision data acquisition systems.
Discrete Op-Amp Input Pair	Low-Power Voltage Regulator Pass Element
Use Scenario: Forming the differential input pair in discrete op-amp designs requiring custom noise or slew-rate specs. IC Role / Device Role / Timing Role: Matched NPN pair (with second MPSA20G or complementary PNP) providing high h_FE and low V_BE mismatch. Use Value: Achieves >80 dB CMRR and <5 nV/√Hz input noise when paired and thermally coupled - exceeding many monolithic op-amps.	Use Scenario: Serving as the series pass transistor in linear regulators powering sensitive analog subsystems. IC Role / Device Role / Timing Role: Current-controlled pass element operating in active region with fixed base drive. Use Value: Provides low-dropout regulation (<0.5 V dropout at 50 mA) with minimal thermal drift due to stable h_FE over temperature.

Audio Preamp Stage

Sensor Signal Conditioning

Use Scenario: Amplifying low-level microphone or piezoelectric sensor outputs prior to ADC sampling.

IC Role / Device Role / Timing Role: Discrete NPN transconductance amplifier in common-emitter topology with emitter degeneration.

Use Value: Delivers stable 20–40 dB voltage gain with <3.0 dB noise figure at 1 kHz, preserving SNR in battery-powered recorders.

Use Scenario: Boosting weak signals from thermistors, photodiodes, or strain gauges in measurement front-ends.

IC Role / Device Role / Timing Role: Linear small-signal gain block with DC-coupled biasing and low input-referred noise.

Use Value: Enables sub-mV signal resolution with minimal added noise, critical for 12–16-bit precision data acquisition systems.

Discrete Op-Amp Input Pair

Low-Power Voltage Regulator Pass Element

Use Scenario: Forming the differential input pair in discrete op-amp designs requiring custom noise or slew-rate specs.

IC Role / Device Role / Timing Role: Matched NPN pair (with second MPSA20G or complementary PNP) providing high h_FE and low V_BE mismatch.

Use Value: Achieves >80 dB CMRR and <5 nV/√Hz input noise when paired and thermally coupled - exceeding many monolithic op-amps.

Use Scenario: Serving as the series pass transistor in linear regulators powering sensitive analog subsystems.

IC Role / Device Role / Timing Role: Current-controlled pass element operating in active region with fixed base drive.

Use Value: Provides low-dropout regulation (<0.5 V dropout at 50 mA) with minimal thermal drift due to stable h_FE over temperature.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC547C	Lower V_CEO (45 V vs. 40 V), higher typical h_FE (420 min), but wider C_obo (8 pF) and no published noise contours.	Better suited for general-purpose switching; less optimal for low-noise analog due to uncharacterized noise performance.	Select BC547C only when noise is non-critical and higher β consistency is required.
2N3904	Identical V_CEO (40 V), lower max I_C (200 mA), tighter h_FE binning (100–300), and documented 5 dB NF at 1 kHz (vs. 3 dB for MPSA20G).	Preferred for digital logic interfacing and moderate-gain amplifiers where noise is secondary to cost and availability.	Choose 2N3904 for cost-sensitive, non-audio applications; retain MPSA20G where sub-3 dB NF is mandatory.

Compared with BC547C and 2N3904, the MPSA20G delivers superior verified low-noise performance and broader h_FE range - making it the preferred choice for precision analog gain stages where signal fidelity outweighs unit cost.

Availability

MPSA20G is available at Aetrix Electronics and suitable for audio preamplifiers, sensor signal conditioners, discrete op-amp input stages, and low-power linear regulator designs requiring stable component supply and RoHS-compliant through-hole packaging.

Supply support for MPSA20G 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 management, analog, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The MPSA20G belongs to onsemi's legacy small-signal transistor product line, engineered for high-fidelity analog amplification in cost-sensitive, high-reliability applications where noise, gain linearity, and thermal robustness are essential.

FAQ

What is the maximum collector-emitter voltage rating for the MPSA20G?

The MPSA20G has a guaranteed minimum V_CEO rating of 40 Vdc, meaning it can safely sustain up to 40 V between collector and emitter with base open. This rating is confirmed in the Absolute Maximum Ratings table of the official onsemi datasheet (Publication Order Number: MPSA20/D), and must not be exceeded to prevent avalanche breakdown or device failure.

Does the MPSA20G have a specified noise figure, and at what conditions is it measured?

Yes, the MPSA20G has a documented noise figure of ≤3.0 dB at 1 kHz with V_CE = 5.0 Vdc, I_C = 1.0 mA, and source resistance R_S = 1 kΩ. This value is plotted in Figure 6 of the onsemi datasheet and reflects its suitability for low-noise preamplifier applications - a key differentiator versus generic small-signal transistors lacking noise characterization.

Is the MPSA20G pin-compatible with the MPSA20 (non-G) variant?

Yes, the MPSA20G is functionally and physically identical to the MPSA20 except for its Pb-free construction. Both share the same TO-92 package outline, identical pinout (Emitter=Pin1, Base=Pin2, Collector=Pin3), and identical electrical specifications - making MPSA20G a direct drop-in replacement where RoHS compliance is required.

What is the thermal resistance from junction-to-ambient for the MPSA20G, and how does it affect PCB layout?

The MPSA20G has a junction-to-ambient thermal resistance (R_JA) of 200°C/W when soldered to a standard PCB per JEDEC test conditions. This means each watt of dissipated power raises the junction temperature by 200°C above ambient - so at 625 mW, ΔT_J ≈ 125°C. Layout must include adequate copper area and airflow to maintain T_J ≤ 150°C, especially in enclosed enclosures.

Can the MPSA20G be used in switching applications, and what are its turn-on/turn-off times?

The MPSA20G is primarily optimized for linear amplification, but it can operate in switching mode with verified t_on ≈ 300 ns and t_off ≈ 300 ns at I_C/I_B = 10 and V_CC = 3.0 V (per Figures 1–2). However, its relatively high C_obo (4.0 pF) and moderate f_T make it less ideal than dedicated switching transistors like the 2N2222A for >1 MHz digital applications.

MPSA20G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 40 V

Vce Saturation (Max) @ Ib, Ic:: 250mV @ 1mA, 10mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 40 @ 5mA, 10V

Power - Max:: 625 mW

Frequency - Transition:: 125MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92 (TO-226)

MPSA20G FAQ

1.How can I place an order for MPSA20G through Aetrix?

Please submit a Request for Quotation (RFQ) for MPSA20G 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 MPSA20G reliable?

The price and inventory of MPSA20G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MPSA20G is usually 5 days.

3.What payment methods are accepted for MPSA20G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MPSA20G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MPSA20G?

MPSA20G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MPSA20G 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 MPSA20G?

For technical support, including MPSA20G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MPSA20G requirements.

6.How does Aetrix verify that MPSA20G is sourced from the original manufacturer or authorized distributors?

All MPSA20G 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 MPSA20G meets industry standards.

7.What is the process for return or replacement of MPSA20G?

All MPSA20G units undergo pre-shipment inspection (PSI). If there is an issue with MPSA20G, 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 MPSA20G part is unused and in its original packaging.

Return procedure for MPSA20G:

1.Submit a request within 90 days.

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

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