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

onsemi 2N6428ABU

Name: 2N6428ABU
Brand: onsemi
SKU: 2N6428ABU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 2N6428ABU

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: 2N6428ABU.pdf

Description:: TRANS NPN 50V 0.2A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

2N6428ABU from Fairchild Semiconductor is an NPN epitaxial silicon small-signal amplifier transistor in TO-92 package, rated for V_CEO = 50 V, I_C = 200 mA, P_C = 625 mW, and f_T = 100–700 MHz. It delivers high DC current gain (h_FE = 250–650) with low noise performance, used in audio preamplifier stages and RF signal conditioning circuits.

For engineers reviewing the 2N6428ABU datasheet, pinout, applications, or equivalent options, key selection criteria include its V_CEO/I_C rating, h_FE consistency across bias points, low V_CE(sat) at 10 mA/0.5 mA drive, Cob = 3 pF, and documented noise figure of 3 dB (100 Hz, RS = 10 kΩ) for low-noise analog front-end design.

Technical Context

This device operates as a linear amplifying element with fixed-emitter bias configuration capability. Its h_FE remains stable across I_C = 10 µA to 1 mA (min 250), and V_CE(sat) is specified at two operating points (0.2 V @ 10 mA/0.5 mA; 0.6 V @ 100 mA/5 mA), supporting both low-power and medium-current gain stages.

The 2N6428ABU exhibits frequency-dependent noise performance: NF = 3 dB @ 100 Hz (RS = 10 kΩ) and 6 dB @ 10 Hz–10 kHz (RS = 500 Ω), confirming its suitability for wideband audio amplification. Cob = 3 pF at V_CB = 10 V enables predictable high-frequency response in tuned amplifier designs.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	50 V - Maximum safe collector-emitter voltage before breakdown in common-emitter configuration.
I_C	200 mA - Continuous collector current limit defining usable dynamic range in linear amplification.
P_C	625 mW - Thermal power dissipation limit at T_A = 25°C, constraining bias point selection in PCB layout.
h_FE	250–650 - DC current gain range across I_C = 10 µA to 1 mA, enabling predictable bias stability in emitter-degenerated stages.
f_T	100–700 MHz - Unity-gain bandwidth indicating usable small-signal amplification up to VHF band.
C_ob	3 pF - Output capacitance at V_CB = 10 V, directly affecting high-frequency roll-off and neutralization requirements.
NF	3 dB @ 100 Hz (RS = 10 kΩ) - Low-noise performance critical for microphone preamp input stages.

Pinout & Package

2N6428ABU uses the standard TO-92 plastic package with 3-pin inline configuration: Emitter (Pin 1), Base (Pin 2), Collector (Pin 3). Lead spacing is 1.27 mm (0.05"), body height ≤3.86 mm, and overall length 4.58 mm.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal in common-base/common-collector configurations	Low-impedance output node; requires direct connection to ground or emitter resistor for bias control.
2 (Base)	Control input for minority-carrier injection	High-impedance gate for current amplification; sensitive to ESD and requires series resistance in driver paths.
3 (Collector)	Current source terminal in common-emitter configuration	Primary output node for voltage gain; must be decoupled from supply rail to prevent oscillation at RF frequencies.

Key Features

Feature	Design Value
High h_FE uniformity	Min 250 across I_C = 10 µA–1 mA ensures consistent DC bias in cascaded amplifier stages without trimming.
Low V_CE(sat)	0.2 V @ 10 mA/0.5 mA enables efficient operation in Class-A audio output buffers with minimal voltage headroom loss.
Controlled Cob	3 pF output capacitance allows accurate prediction of Miller effect and simplifies high-frequency compensation network design.
Low-noise operation	NF = 3 dB @ 100 Hz (RS = 10 kΩ) supports high-SNR signal acquisition in sensor interface and instrumentation amplifier inputs.

Applications

Audio Preamplifier Stage	RF Signal Amplifier
Use Scenario: Low-level microphone or piezoelectric sensor signal amplification prior to ADC sampling. IC Role / Device Role / Timing Role: Small-signal NPN amplifier in common-emitter configuration with emitter degeneration. Use Value: High h_FE and 3 dB NF at 100 Hz ensure >60 dB SNR in 20 Hz–20 kHz audio band without active filtering.	Use Scenario: Intermediate-frequency (IF) amplification in AM/FM radio receivers operating at 455 kHz or 10.7 MHz. IC Role / Device Role / Timing Role: Linear voltage amplifier with tuned collector load for selective gain peaking. Use Value: f_T up to 700 MHz and Cob = 3 pF support stable gain up to 30 MHz with minimal external neutralization.
Instrumentation Input Buffer	DC-Coupled Sensor Interface
Use Scenario: High-input-impedance buffer for thermocouple or strain gauge bridges with millivolt-level outputs. IC Role / Device Role / Timing Role: Common-collector (emitter-follower) configured for unity-gain buffering and impedance transformation. Use Value: V_CEO = 50 V and h_FE ≥250 allow direct coupling to ±15 V rails while maintaining linearity over full temperature range.	Use Scenario: Direct-coupled amplification of slow-varying industrial sensor signals (e.g., RTD, pH probe) with no AC coupling capacitors. IC Role / Device Role / Timing Role: DC-stable common-emitter amplifier with base bias network and emitter resistor feedback. Use Value: ICEO ≤25 nA and TJ = 150°C rating ensure long-term offset stability in unregulated 85°C ambient environments.

Audio Preamplifier Stage

RF Signal Amplifier

Use Scenario: Low-level microphone or piezoelectric sensor signal amplification prior to ADC sampling.

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

Use Value: High h_FE and 3 dB NF at 100 Hz ensure >60 dB SNR in 20 Hz–20 kHz audio band without active filtering.

Use Scenario: Intermediate-frequency (IF) amplification in AM/FM radio receivers operating at 455 kHz or 10.7 MHz.

IC Role / Device Role / Timing Role: Linear voltage amplifier with tuned collector load for selective gain peaking.

Use Value: f_T up to 700 MHz and Cob = 3 pF support stable gain up to 30 MHz with minimal external neutralization.

Instrumentation Input Buffer

DC-Coupled Sensor Interface

Use Scenario: High-input-impedance buffer for thermocouple or strain gauge bridges with millivolt-level outputs.

IC Role / Device Role / Timing Role: Common-collector (emitter-follower) configured for unity-gain buffering and impedance transformation.

Use Value: V_CEO = 50 V and h_FE ≥250 allow direct coupling to ±15 V rails while maintaining linearity over full temperature range.

Use Scenario: Direct-coupled amplification of slow-varying industrial sensor signals (e.g., RTD, pH probe) with no AC coupling capacitors.

IC Role / Device Role / Timing Role: DC-stable common-emitter amplifier with base bias network and emitter resistor feedback.

Use Value: ICEO ≤25 nA and TJ = 150°C rating ensure long-term offset stability in unregulated 85°C ambient environments.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
2N5088	V_CEO = 30 V (vs. 50 V), h_FE min = 400, f_T = 50 MHz	Limited to lower-voltage bias networks; higher h_FE but narrower bandwidth	Select when ultra-high gain at sub-10 MHz is prioritized over voltage headroom or RF extension.
BC548C	V_CEO = 30 V, I_C = 100 mA, h_FE = 420–800, Cob = 4 pF	Lower power rating and reduced f_T margin; wider h_FE spread increases production binning variance	Choose for cost-sensitive consumer audio where 30 V compliance suffices and tighter h_FE tolerance is not required.

Compared with 2N5088 and BC548C, the 2N6428ABU provides superior voltage headroom (50 V), broader bandwidth (up to 700 MHz), and lower noise at audio frequencies-making it optimal for high-fidelity, wide-dynamic-range analog signal chains where reliability under varying supply conditions is critical.

Availability

2N6428ABU is available at Aetrix Electronics and suitable for audio preamplifier stages, RF signal amplifiers, and instrumentation input buffers requiring stable component supply across industrial and professional electronics production cycles.

Supply support for 2N6428ABU 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 2N6428ABU belongs to Fairchild's legacy 2N-series general-purpose NPN transistor family, designed specifically for high-fidelity audio amplification, low-noise sensor interfacing, and broadband RF signal conditioning.

FAQ

What is the maximum collector-emitter voltage rating for the 2N6428ABU?

The 2N6428ABU has a maximum collector-emitter voltage (V_CEO) rating of 50 V at T_A = 25°C. This rating applies in common-emitter configuration with base open. Exceeding this voltage risks avalanche breakdown and permanent device degradation. Derating is required above 25°C per the datasheet's thermal curves.

Does the 2N6428ABU have a specified noise figure, and under what conditions?

Yes, the 2N6428ABU specifies noise figure (NF) as 3 dB at 100 Hz with RS = 10 kΩ and BW = 1 Hz, and 6 dB across 10 Hz–10 kHz with RS = 500 Ω. These values are measured per the 2N6428A variant's characterization and apply directly to the 2N6428ABU, confirming its suitability for low-noise audio front-end use.

What is the pin configuration of the 2N6428ABU in its TO-92 package?

The 2N6428ABU uses standard TO-92 pinout: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector, with leads arranged left-to-right when viewing the flat side of the package with leads pointing downward. This matches JEDEC TO-92 outline and is verified in Fairchild's Rev. A datasheet mechanical drawing.

Can the 2N6428ABU replace the 2N5088 in existing designs?

The 2N6428ABU is not a direct drop-in replacement for the 2N5088 due to differing V_CEO (50 V vs. 30 V) and f_T (up to 700 MHz vs. 50 MHz). While both are NPN small-signal transistors, substituting requires verification of voltage margin, bandwidth needs, and bias network stability-especially in high-gain or RF-critical circuits.

What is the junction temperature limit and storage temperature range for the 2N6428ABU?

The 2N6428ABU has a maximum junction temperature (T_J) of 150°C and a storage temperature range (T_STG) of –55°C to +150°C. These limits are defined in the Absolute Maximum Ratings table and govern thermal design, heatsinking requirements, and long-term reliability in sealed or high-ambient environments.

2N6428ABU Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Bulk

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 200 mA

Voltage - Collector Emitter Breakdown (Max):: 50 V

Vce Saturation (Max) @ Ib, Ic:: 600mV @ 5mA, 100mA

Current - Collector Cutoff (Max):: 25nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 250 @ 100µA, 5V

Power - Max:: 625 mW

Frequency - Transition:: 700MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

2N6428ABU FAQ

1.How can I place an order for 2N6428ABU through Aetrix?

Please submit a Request for Quotation (RFQ) for 2N6428ABU 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 2N6428ABU reliable?

The price and inventory of 2N6428ABU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 2N6428ABU is usually 5 days.

3.What payment methods are accepted for 2N6428ABU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 2N6428ABU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 2N6428ABU?

2N6428ABU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 2N6428ABU 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 2N6428ABU?

For technical support, including 2N6428ABU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 2N6428ABU requirements.

6.How does Aetrix verify that 2N6428ABU is sourced from the original manufacturer or authorized distributors?

All 2N6428ABU 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 2N6428ABU meets industry standards.

7.What is the process for return or replacement of 2N6428ABU?

All 2N6428ABU units undergo pre-shipment inspection (PSI). If there is an issue with 2N6428ABU, 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 2N6428ABU part is unused and in its original packaging.

Return procedure for 2N6428ABU:

1.Submit a request within 90 days.

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

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