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

onsemi BC548_D81Z

Name: BC548_D81Z
Brand: onsemi
SKU: BC548_D81Z
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC548_D81Z

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BC548_D81Z.pdf

Description:: TRANS NPN 30V 0.1A TO-92-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC548_D81Z from ON Semiconductor is a general-purpose NPN epitaxial silicon transistor in TO-92 package, rated for V_CEO = 30 V, I_C = 100 mA, and P_C = 500 mW, with h_FE range of 420–800 (Class C), used in low-voltage switching and small-signal amplification circuits.

For engineers reviewing the BC548_D81Z datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, TO-92 terminal mapping, noise performance (NF = 2.0–10.0 dB), saturation behavior (V_CE(sat) ≤ 250 mV @ I_C = 10 mA), and validated alternative options for discrete BJT replacement.

Technical Context

This device operates as a medium-gain, low-noise NPN bipolar junction transistor optimized for linear amplification and digital switching in DC-coupled or AC-coupled configurations. It features a maximum f_T of 300 MHz at I_C = 10 mA and exhibits Cob = 3.5–6.0 pF and Cib = 9 pF for stable high-frequency biasing.

Its V_BE(on) ranges from 580–700 mV at I_C = 2 mA, enabling predictable base drive design; V_BE(sat) reaches 700–900 mV under switching conditions, supporting reliable turn-on margin in logic-level interface applications.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	30 V - Maximum collector-emitter voltage before breakdown; defines safe operating range in common-emitter amplifier or switch topologies.
I_C	100 mA - Continuous DC collector current limit; sets upper bound for load-driving capability in relay drivers or LED interfaces.
h_FE (Class C)	420–800 - DC current gain range at V_CE = 5 V, I_C = 2 mA; enables low-base-current biasing in amplifier stages.
V_CE(sat)	≤250 mV @ I_C = 10 mA, I_B = 0.5 mA - Low saturation voltage ensures minimal power loss and heat generation in switching mode.
NF	2.0–10.0 dB @ V_CE = 5 V, I_C = 200 μA, f = 1 kHz - Confirmed noise figure supports audio preamp and sensor signal conditioning use.
f_T	300 MHz - Current gain-bandwidth product; validates suitability for RF front-end buffering up to ~100 MHz with gain margin.
P_C	500 mW - Total power dissipation at T_A = 25°C; determines thermal derating requirements in enclosed PCB environments.

Pinout & Package

BC548_D81Z is housed in a JEDEC TO-92 3-lead molded plastic package with straight leads (bulk packing). Pin 1 is Collector, Pin 2 is Base, Pin 3 is Emitter - confirmed per Fairchild/ON Semiconductor mechanical drawings and ordering information.

Pin/Terminal	Circuit Role	Design Meaning
1 (Collector)	Main current output node in common-emitter configuration	Connected to load or supply rail; must withstand V_CEO = 30 V and dissipate up to 500 mW under bias.
2 (Base)	Control input for minority-carrier injection	Requires precise current limiting (e.g., via series resistor) to achieve target h_FE-dependent I_C without overdrive.
3 (Emitter)	Current return path and reference node	Typically grounded or tied to emitter resistor for bias stability; defines V_BE forward drop (580–700 mV).

Key Features

Feature	Design Value
Switching & Amplifier Dual Use	Validated by V_CE(sat) ≤ 250 mV and h_FE ≥ 420 - enables single-part reuse across digital logic interfaces and analog gain stages.
Low-Noise Operation	NF = 2.0–10.0 dB at audio frequencies - supports microphone preamplifiers and sensor signal chains where SNR is critical.
High f_T Performance	300 MHz bandwidth - permits stable operation in IF amplifiers and clock buffer circuits below 100 MHz.
TO-92 Mechanical Standardization	JEDEC-compliant 3-lead through-hole package - ensures compatibility with legacy wave-solder processes and manual prototyping.
Complementary Pair Availability	Direct complement is BC558 (PNP); both share matching V_CEO, I_C, and h_FE grading - simplifies push-pull stage design.

Applications

Audio Preamp Stage	Microcontroller GPIO Driver
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors before ADC sampling. IC Role / Device Role / Timing Role: Small-signal NPN amplifier in common-emitter configuration with emitter degeneration. Use Value: NF = 2.0–10.0 dB and h_FE ≥ 420 ensure high SNR and stable gain control at 1–20 kHz without external bias trimming.	Use Scenario: Driving LEDs, relays, or MOSFET gates from 3.3 V or 5 V microcontroller outputs. IC Role / Device Role / Timing Role: Digital switch in common-emitter configuration with base current limiting. Use Value: V_CE(sat) ≤ 250 mV minimizes power loss and self-heating during sustained on-state, extending reliability in 24/7 control systems.
DC Power Supply Error Amplifier	Signal Level Shifter
Use Scenario: Compensating feedback loop in linear voltage regulators (e.g., LM317-based designs). IC Role / Device Role / Timing Role: Transconductance amplifier comparing reference and output voltages. Use Value: V_BE(on) = 580–700 mV and tight h_FE tolerance enable accurate error signal translation with <1% regulation drift.	Use Scenario: Translating logic levels between 3.3 V MCU and 5 V peripheral buses (e.g., UART, SPI). IC Role / Device Role / Timing Role: Active pull-up/pull-down level translator using emitter-follower or common-base topology. Use Value: f_T = 300 MHz and low C_ob = 3.5–6.0 pF preserve signal integrity up to 10 Mbps without added propagation delay.

Audio Preamp Stage

Microcontroller GPIO Driver

Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors before ADC sampling.

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

Use Value: NF = 2.0–10.0 dB and h_FE ≥ 420 ensure high SNR and stable gain control at 1–20 kHz without external bias trimming.

Use Scenario: Driving LEDs, relays, or MOSFET gates from 3.3 V or 5 V microcontroller outputs.

IC Role / Device Role / Timing Role: Digital switch in common-emitter configuration with base current limiting.

Use Value: V_CE(sat) ≤ 250 mV minimizes power loss and self-heating during sustained on-state, extending reliability in 24/7 control systems.

DC Power Supply Error Amplifier

Signal Level Shifter

Use Scenario: Compensating feedback loop in linear voltage regulators (e.g., LM317-based designs).

IC Role / Device Role / Timing Role: Transconductance amplifier comparing reference and output voltages.

Use Value: V_BE(on) = 580–700 mV and tight h_FE tolerance enable accurate error signal translation with <1% regulation drift.

Use Scenario: Translating logic levels between 3.3 V MCU and 5 V peripheral buses (e.g., UART, SPI).

IC Role / Device Role / Timing Role: Active pull-up/pull-down level translator using emitter-follower or common-base topology.

Use Value: f_T = 300 MHz and low C_ob = 3.5–6.0 pF preserve signal integrity up to 10 Mbps without added propagation delay.

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN general-purpose transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC548C (ON Semiconductor)	Same die, identical h_FE (420–800), V_CEO = 30 V, TO-92 package - differs only in marking and packaging format (ammo vs bulk).	No functional difference; suitable for same PCB layouts and thermal environments.	Select BC548C when tape-and-reel or ammo-packaged variants are required for automated assembly.
2N3904 (ON Semiconductor)	Higher V_CEO = 40 V, lower h_FE (100–300), same TO-92 footprint - not Class C graded; higher V_BE(on) (600–750 mV).	Better suited for higher-voltage switching but less optimal for low-noise amplification due to wider h_FE spread and higher NF.	Choose 2N3904 where robustness against transient overvoltage is prioritized over gain consistency or noise floor.

Compared with BC548_D81Z, BC548C offers identical electrical behavior with different packaging logistics, while 2N3904 trades gain precision and noise performance for broader voltage tolerance - making BC548_D81Z preferable for audio and precision biasing, and 2N3904 better for ruggedized digital interfacing.

Availability

BC548_D81Z is available at Aetrix Electronics and suitable for audio preamplifiers, microcontroller GPIO drivers, and DC power supply error amplifiers requiring stable component supply, consistent h_FE grading, and TO-92 through-hole compatibility.

Supply support for BC548_D81Z 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power and signal management solutions, with roots in Fairchild Semiconductor's discrete portfolio.

The BC548_D81Z belongs to ON Semiconductor's legacy general-purpose BJT family, designed for cost-sensitive, high-volume applications in consumer electronics, industrial controls, and educational hardware where reliability, consistency, and manufacturability are essential.

FAQ

What is the pin configuration of BC548_D81Z?

The BC548_D81Z uses a standard TO-92 package with Pin 1 = Collector, Pin 2 = Base, Pin 3 = Emitter - confirmed by Fairchild/ON Semiconductor mechanical drawings and ordering documentation. This pinout is consistent across all BC546–BC550 variants and matches industry-standard NPN TO-92 orientation.

Is BC548_D81Z suitable for low-noise audio amplification?

Yes, BC548_D81Z is specified with a noise figure of 2.0–10.0 dB at 1 kHz under typical bias conditions (V_CE = 5 V, I_C = 200 μA), making it appropriate for electret microphone preamplifiers and sensor signal conditioning where SNR matters. Its Class C h_FE grading also improves gain predictability in cascaded stages.

What is the maximum collector-emitter voltage rating for BC548_D81Z?

The BC548_D81Z has a V_CEO rating of 30 V, meaning it can safely sustain up to 30 V between collector and emitter with the base open. This value is fixed for BC548/BC549 variants and is lower than BC546 (65 V) or BC547 (45 V), so voltage margin must be verified in high-side switch or amplifier designs.

Does BC548_D81Z have a direct PNP complement?

Yes, BC558 is the designated PNP complement to BC548_D81Z - sharing identical V_CEO = 30 V, I_C = 100 mA, and TO-92 packaging, with matched h_FE grading (e.g., BC558C pairs with BC548C). This pairing is explicitly documented in Fairchild's original datasheet for push-pull and differential amplifier implementations.

Can BC548_D81Z replace BC547B in an existing design?

BC548_D81Z can replace BC547B only if the circuit operates within its lower V_CEO (30 V vs 45 V) and V_CB (30 V vs 50 V) limits. While both share TO-92 packaging and similar h_FE, BC548_D81Z's reduced voltage ratings require verification of worst-case transient and steady-state stress - especially in power supply feedback or inductive load switching.

BC548_D81Z Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

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

Voltage - Collector Emitter Breakdown (Max):: 30 V

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

Current - Collector Cutoff (Max):: 15nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 110 @ 2mA, 5V

Power - Max:: 500 mW

Frequency - Transition:: 300MHz

Operating Temperature:: 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

BC548_D81Z FAQ

1.How can I place an order for BC548_D81Z through Aetrix?

Please submit a Request for Quotation (RFQ) for BC548_D81Z 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 BC548_D81Z reliable?

The price and inventory of BC548_D81Z are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC548_D81Z is usually 5 days.

3.What payment methods are accepted for BC548_D81Z?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC548_D81Z transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC548_D81Z?

BC548_D81Z orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC548_D81Z 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 BC548_D81Z?

For technical support, including BC548_D81Z datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC548_D81Z requirements.

6.How does Aetrix verify that BC548_D81Z is sourced from the original manufacturer or authorized distributors?

All BC548_D81Z 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 BC548_D81Z meets industry standards.

7.What is the process for return or replacement of BC548_D81Z?

All BC548_D81Z units undergo pre-shipment inspection (PSI). If there is an issue with BC548_D81Z, 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 BC548_D81Z part is unused and in its original packaging.

Return procedure for BC548_D81Z:

1.Submit a request within 90 days.

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

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