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

onsemi BC847ALT1

Name: BC847ALT1
Brand: onsemi
SKU: BC847ALT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC847ALT1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: -

Datasheet:: BC847ALT1.pdf

Description:: TRANS NPN 45V 100MA SOT23

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC847ALT1 from onsemi is an NPN silicon general-purpose transistor in SOT-23 package, rated for 45 V_CEO, 100 mA continuous collector current, and 225 mW power dissipation on FR-5 board; it delivers h_FE = 110–220 at I_C = 10 mA, V_CE = 5 V, and is widely used in low-voltage switching and amplification circuits in consumer and industrial electronics.

For engineers reviewing the BC847ALT1 datasheet, pinout, applications, or equivalent options, key selection considerations include its V_CEO = 45 V rating, h_FE binning (A-grade), SOT-23 thermal performance (R_JA = 556 °C/W), and Pb-free compliance with MSL Level 1 handling.

Technical Context

The BC847ALT1 belongs to onsemi's preferred BC846/847/848 family of general-purpose bipolar transistors optimized for cost-sensitive linear and switching applications. It operates as a discrete NPN amplifier/switch with fixed gain binning (A-grade) and specified saturation behavior at I_C/I_B = 10 and 20.

Its electrical behavior is characterized by V_BE(sat) ≤ 0.7 V at I_C = 10 mA/I_B = 0.5 mA, f_T = 100 MHz at I_C = 10 mA/V_CE = 5 V, and C_obo = 4.5 pF at V_CB = 10 V - parameters validated across −55°C to +150°C junction temperature range.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - maximum allowable collector-emitter voltage before breakdown under open-base conditions; defines safe operating voltage headroom in 24 V and lower supply rails.
I_C (continuous)	100 mA - maximum DC collector current sustainable without thermal derating; supports medium-current switching (e.g., LED drivers, relay coils).
h_FE (min–max)	110–220 - guaranteed DC current gain range at I_C = 10 mA, V_CE = 5 V; enables predictable biasing in amplifier stages and ensures reliable turn-on in saturated switch designs.
V_CE(sat)	≤ 0.25 V - collector-emitter saturation voltage at I_C = 10 mA/I_B = 0.5 mA; minimizes conduction loss and self-heating in low-power switching applications.
f_T	100 MHz - transition frequency at I_C = 10 mA/V_CE = 5 V; supports audio-frequency amplification and fast digital signal switching up to ~10 MHz.
R_JA	556 °C/W - junction-to-ambient thermal resistance on FR-5 board; determines temperature rise under 225 mW dissipation and informs PCB copper area requirements.

Pinout & Package

SOT-23 (Case 318, Style 6) surface-mount package with 3 terminals, 1.0 mm pitch, and JEDEC-compliant footprint (2.0 × 1.25 × 0.95 mm). Moisture Sensitivity Level 1 - floor life unlimited at ≤30°C/60% RH.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal for forward-biased junction; requires ~0.66 V to initiate conduction; base current must be sized per h_FE to ensure saturation.
2	Emitter	Current return path; connected to circuit ground or low-side reference; polarity defines NPN operation (current flows into collector, out emitter).
3	Collector	Output current terminal; handles switched load current up to 100 mA; voltage swing limited by V_CEO = 45 V rating.

Key Features

Feature	Design Value
Pb-free packaging	RoHS-compliant SOT-23 construction with matte tin lead finish; qualified for lead-free reflow (J-STD-020, MSL Level 1).
ESD robustness	Human Body Model >4000 V and Machine Model >400 V - reduces risk of damage during handling and board assembly.
Wide temperature range	Junction/storage range −55°C to +150°C - supports operation in automotive under-hood, industrial control, and outdoor equipment environments.
Low V_BE(on)	580–700 mV at I_C = 2 mA/V_CE = 5 V - enables reliable turn-on with low-voltage microcontroller GPIOs (e.g., 3.3 V logic).

Applications

LED Driver Circuit	Microcontroller Interface
Use Scenario: Driving 20 mA indicator LEDs from 3.3 V or 5 V MCU outputs in portable instrumentation. IC Role / Device Role / Timing Role: NPN switch controlling LED anode current path to ground; operated in saturation mode. Use Value: V_CE(sat) ≤ 0.25 V ensures <10 mW power loss per LED channel, preserving battery life and minimizing thermal stress.	Use Scenario: Level-shifting and signal inversion between 1.8 V/3.3 V logic domains and 5 V peripherals. IC Role / Device Role / Timing Role: Digital inverter/buffer stage with rail-to-rail output swing and sub-10 ns propagation delay. Use Value: f_T = 100 MHz supports clean edge transitions up to 10 MHz clock rates without slew-induced distortion.
Low-Voltage Power Switch	Audio Pre-amplifier Stage
Use Scenario: Enabling/disabling 12 V sensor modules or small solenoids in building automation systems. IC Role / Device Role / Timing Role: High-side or low-side load switch controlled by MCU GPIO; biased in active region for linear regulation or saturated for on/off control. Use Value: V_CEO = 45 V provides 3× safety margin over 12 V nominal supply, preventing avalanche failure during load dump transients.	Use Scenario: First-stage gain block in battery-powered audio recorders with electret microphone input. IC Role / Device Role / Timing Role: Common-emitter amplifier with fixed bias network; configured for mid-band voltage gain and low-noise operation. Use Value: NF = 10 dB at I_C = 0.2 mA enables SNR >60 dB in 20 Hz–20 kHz band without requiring external noise filtering.

LED Driver Circuit

Microcontroller Interface

Use Scenario: Driving 20 mA indicator LEDs from 3.3 V or 5 V MCU outputs in portable instrumentation.

IC Role / Device Role / Timing Role: NPN switch controlling LED anode current path to ground; operated in saturation mode.

Use Value: V_CE(sat) ≤ 0.25 V ensures <10 mW power loss per LED channel, preserving battery life and minimizing thermal stress.

Use Scenario: Level-shifting and signal inversion between 1.8 V/3.3 V logic domains and 5 V peripherals.

IC Role / Device Role / Timing Role: Digital inverter/buffer stage with rail-to-rail output swing and sub-10 ns propagation delay.

Use Value: f_T = 100 MHz supports clean edge transitions up to 10 MHz clock rates without slew-induced distortion.

Low-Voltage Power Switch

Audio Pre-amplifier Stage

Use Scenario: Enabling/disabling 12 V sensor modules or small solenoids in building automation systems.

IC Role / Device Role / Timing Role: High-side or low-side load switch controlled by MCU GPIO; biased in active region for linear regulation or saturated for on/off control.

Use Value: V_CEO = 45 V provides 3× safety margin over 12 V nominal supply, preventing avalanche failure during load dump transients.

Use Scenario: First-stage gain block in battery-powered audio recorders with electret microphone input.

IC Role / Device Role / Timing Role: Common-emitter amplifier with fixed bias network; configured for mid-band voltage gain and low-noise operation.

Use Value: NF = 10 dB at I_C = 0.2 mA enables SNR >60 dB in 20 Hz–20 kHz band without requiring external noise filtering.

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
BC847BLT1	Higher h_FE bin (200–450 vs. 110–220); otherwise identical ratings, package, and pinout.	Preferred where higher gain reduces required base drive current (e.g., weak-signal amplification or high-impedance bias networks).	Select BC847BLT1 when tighter gain control or lower base current is critical; BC847ALT1 remains optimal for predictable saturation in switching.
MMBT3904LT1G	Same SOT-23 package and pinout; V_CEO = 40 V (vs. 45 V), h_FE = 100–300, and slightly higher V_CE(sat) (0.3 V typical).	Valid alternative in 3.3 V/5 V digital logic interfaces but less suitable for 24 V industrial switching due to lower V_CEO.	Choose MMBT3904LT1G only if legacy design compatibility or second-source qualification is required; BC847ALT1 offers superior voltage margin and lower saturation loss.

Compared with BC847BLT1 and MMBT3904LT1G, the BC847ALT1 provides the best balance of voltage margin (45 V), low saturation loss (≤0.25 V), and predictable A-grade gain for cost-sensitive switching - making it ideal for production designs where consistency and thermal efficiency are prioritized over maximum h_FE.

Availability

BC847ALT1 is available at Aetrix Electronics and suitable for LED driver circuits, microcontroller interface logic, and low-voltage power switching applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for BC847ALT1 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 focused on energy-efficient innovation for automotive, industrial, cloud, medical, and IoT applications.

The BC847ALT1 belongs to onsemi's BC846/847/848 Preferred Devices family - engineered for high-volume, cost-optimized general-purpose analog functions including switching, amplification, and signal conditioning in space-constrained PCBs.

FAQ

What is the maximum collector-emitter voltage rating for BC847ALT1?

The BC847ALT1 has a maximum collector-emitter voltage (V_CEO) rating of 45 Vdc under open-base conditions. This value is confirmed in the "Maximum Ratings" table of the official onsemi datasheet (Rev. 6, June 2004) and applies at T_A = 25°C. Exceeding this voltage risks irreversible breakdown, especially in inductive load switching scenarios where voltage spikes may occur.

Is BC847ALT1 RoHS compliant and what is its moisture sensitivity level?

Yes, BC847ALT1 is RoHS compliant and offered in Pb-free packaging (denoted by suffix "G" in variants like BC847ALT1G). Its moisture sensitivity level is MSL Level 1 per J-STD-020, meaning it has unlimited floor life when stored at ≤30°C and ≤60% relative humidity - eliminating bake requirements prior to reflow soldering.

What is the DC current gain (h_FE) range for BC847ALT1 and how is it tested?

The BC847ALT1 has a guaranteed h_FE range of 110 to 220, measured at I_C = 10 mA and V_CE = 5.0 V with T_A = 25°C. This A-grade binning is verified during production test and documented in the "Electrical Characteristics" table of the onsemi BC846ALT1 Series datasheet. Gain varies with temperature and operating point, so design margins should account for min/max extremes.

Does BC847ALT1 support operation at elevated temperatures such as in automotive under-hood environments?

Yes, BC847ALT1 is rated for junction and storage temperatures from −55°C to +150°C. Its thermal resistance (R_JA = 556 °C/W on FR-5 board) and stable electrical parameters across this range make it suitable for non-safety-critical automotive applications like cabin sensors and body control modules - provided PCB layout provides adequate copper area for heat dissipation.

What are the key differences between BC847ALT1 and BC847CLT1?

The BC847ALT1 and BC847CLT1 share identical SOT-23 package and pinout but differ in DC current gain: BC847ALT1 is A-grade (h_FE = 110–220), while BC847CLT1 is C-grade (h_FE = 420–800). Both have same V_CEO = 45 V and I_C = 100 mA ratings. The C-grade variant suits high-gain analog stages; the A-grade BC847ALT1 is preferred for consistent saturation in digital switching.

BC847ALT1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: *

Package/Case:: -

Packaging:: Cut Tape (CT)

Product Status:: Obsolete

Transistor Type:: -

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

Voltage - Collector Emitter Breakdown (Max):: -

Vce Saturation (Max) @ Ib, Ic:: -

Current - Collector Cutoff (Max):: -

DC Current Gain (hFE) (Min) @ Ic, Vce:: -

Power - Max:: -

Frequency - Transition:: -

Operating Temperature:: -

Grade:: -

Qualification:: -

Mounting Type:: -

Supplier Device Package:: -

BC847ALT1 FAQ

1.How can I place an order for BC847ALT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for BC847ALT1 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 BC847ALT1 reliable?

The price and inventory of BC847ALT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC847ALT1 is usually 5 days.

3.What payment methods are accepted for BC847ALT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC847ALT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC847ALT1?

BC847ALT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC847ALT1 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 BC847ALT1?

For technical support, including BC847ALT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC847ALT1 requirements.

6.How does Aetrix verify that BC847ALT1 is sourced from the original manufacturer or authorized distributors?

All BC847ALT1 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 BC847ALT1 meets industry standards.

7.What is the process for return or replacement of BC847ALT1?

All BC847ALT1 units undergo pre-shipment inspection (PSI). If there is an issue with BC847ALT1, 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 BC847ALT1 part is unused and in its original packaging.

Return procedure for BC847ALT1:

1.Submit a request within 90 days.

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

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