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

onsemi BC856ALT1

Name: BC856ALT1
Brand: onsemi
SKU: BC856ALT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC856ALT1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: -

Datasheet:: BC856ALT1.pdf

Description:: TRANS PNP 65V 100MA SOT23

Quantity:: RFQ Add To RFQ list

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Inventory:6,519

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Product details

Overview

BC856ALT1 from onsemi is a PNP silicon general-purpose transistor in SOT-23 package, rated for −65 V V_CEO, −100 mA I_C continuous, and 100 MHz f_T, used in low-power switching and linear amplification circuits such as level shifters, current mirrors, and discrete logic interfaces in automotive body control modules.

For engineers reviewing the BC856ALT1 datasheet, pinout, applications, or equivalent options, this page delivers verified electrical parameters, thermal derating behavior, AEC-Q101 qualification status, and real-world design context for reliable component selection in industrial and automotive embedded systems.

Technical Context

The BC856ALT1 operates as a discrete PNP bipolar junction transistor with fixed emitter-base and collector-base junctions optimized for DC amplification and fast switching. Its h_FE range of 125–250 at I_C = −10 mA and V_CE = −5 V supports predictable biasing in Class-A amplifiers and saturated-switch configurations.

Thermal performance is defined by R_JA = 556 °C/W on FR-5 board and 417 °C/W on alumina substrate, with junction temperature rated from −55 °C to +150 °C. Switching times (t_d = 35 ns, t_r = 25 ns, t_s = 310 ns, t_f = 40 ns) confirm suitability for ≤1 MHz digital signal routing and pulse-width modulation drivers.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−65 V - Maximum collector-emitter voltage before breakdown; enables use in 48 V automotive supply rail monitoring and high-side load switching.
I_C (cont.)	−100 mA - Continuous collector current rating; supports driving small relays, LEDs, or gate resistors in MOSFET driver stages.
h_FE	125–250 @ I_C = −10 mA - DC current gain range defining base drive requirements for predictable saturation in switching applications.
f_T	100 MHz - Current-gain bandwidth product; validates stable operation up to ~10 MHz small-signal amplification with adequate phase margin.
V_CE(sat)	−0.3 V @ I_C = −10 mA / I_B = −0.5 mA - Low saturation voltage minimizes power loss and self-heating during on-state conduction.
C_ob	4.5 pF @ V_CB = −10 V - Output capacitance limiting high-frequency response; critical for EMI filtering and RF stage isolation.

Pinout & Package

SOT-23 (TO-236) surface-mount package, 2.90 × 1.30 × 1.00 mm, 3-pin configuration with gull-wing leads. RoHS-compliant, Pb-free, halogen-free/BFR-free construction.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal for forward-biased PNP operation; requires negative base current relative to emitter to turn on.
2	Emitter	Current source terminal; connected to higher potential (e.g., V_CC) in common-emitter switching configurations.
3	Collector	Current sink terminal; tied to load and ground reference in high-side switch topologies or active loads in amplifier stages.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive under-hood applications including engine control units and lighting modules requiring extended temperature cycling and humidity resistance.
Low V_CE(sat)	−0.3 V enables <10 mW dissipation at 10 mA load current, reducing thermal stress in space-constrained PCB layouts.
High f_T	100 MHz bandwidth supports clean edge integrity in 1–5 MHz clock buffering and pulse shaping without added compensation.
Robust SOA	Single-pulse safe operating area extends to −65 V / −100 mA at 25 °C, allowing transient overvoltage tolerance in inductive load switching.

Applications

Automotive Body Control Unit	Industrial Sensor Interface
Use Scenario: Level-shifting signals between 5 V microcontroller GPIOs and 12 V vehicle bus lines in door module controllers. IC Role / Device Role / Timing Role: PNP switch configured in common-emitter mode to invert and translate logic levels while sourcing current to pull-up networks. Use Value: −65 V V_CEO withstands load-dump transients; AEC-Q101 qualification ensures reliability across −40 °C to +125 °C ambient.	Use Scenario: Amplifying low-level analog outputs from thermistors or bridge sensors into ADC input ranges within programmable logic controllers. IC Role / Device Role / Timing Role: Linear-mode PNP amplifier in common-collector (emitter-follower) configuration for impedance matching and noise rejection. Use Value: h_FE ≥125 ensures stable gain at µA-level sensor currents; low NF (10 dB) preserves signal-to-noise ratio in 1 kHz bandwidth.
Consumer Power Management	Medical Diagnostic Equipment
Use Scenario: Enabling/disabling auxiliary power rails in battery-powered portable devices using microcontroller-driven enable signals. IC Role / Device Role / Timing Role: High-side load switch with base resistor network controlling conduction state of BC856ALT1 in series with V_DD path. Use Value: −0.3 V V_CE(sat) limits dropout to <30 mV at 100 mA, preserving >97% efficiency in 3.3 V supply domains.	Use Scenario: Isolating patient-connected analog front-end stages from digital processing sections in ECG monitor signal chains. IC Role / Device Role / Timing Role: Discrete PNP buffer stage providing galvanic separation and current gain between isolated op-amp outputs and ADC inputs. Use Value: C_ob = 4.5 pF minimizes capacitive coupling across isolation barriers; 150 °C max T_J supports sterilization cycle compliance.

Automotive Body Control Unit

Industrial Sensor Interface

Use Scenario: Level-shifting signals between 5 V microcontroller GPIOs and 12 V vehicle bus lines in door module controllers.

IC Role / Device Role / Timing Role: PNP switch configured in common-emitter mode to invert and translate logic levels while sourcing current to pull-up networks.

Use Value: −65 V V_CEO withstands load-dump transients; AEC-Q101 qualification ensures reliability across −40 °C to +125 °C ambient.

Use Scenario: Amplifying low-level analog outputs from thermistors or bridge sensors into ADC input ranges within programmable logic controllers.

IC Role / Device Role / Timing Role: Linear-mode PNP amplifier in common-collector (emitter-follower) configuration for impedance matching and noise rejection.

Use Value: h_FE ≥125 ensures stable gain at µA-level sensor currents; low NF (10 dB) preserves signal-to-noise ratio in 1 kHz bandwidth.

Consumer Power Management

Medical Diagnostic Equipment

Use Scenario: Enabling/disabling auxiliary power rails in battery-powered portable devices using microcontroller-driven enable signals.

IC Role / Device Role / Timing Role: High-side load switch with base resistor network controlling conduction state of BC856ALT1 in series with V_DD path.

Use Value: −0.3 V V_CE(sat) limits dropout to <30 mV at 100 mA, preserving >97% efficiency in 3.3 V supply domains.

Use Scenario: Isolating patient-connected analog front-end stages from digital processing sections in ECG monitor signal chains.

IC Role / Device Role / Timing Role: Discrete PNP buffer stage providing galvanic separation and current gain between isolated op-amp outputs and ADC inputs.

Use Value: C_ob = 4.5 pF minimizes capacitive coupling across isolation barriers; 150 °C max T_J supports sterilization cycle compliance.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC857BLT1G	V_CEO = −45 V, h_FE = 220–475, same SOT-23 package and pinout	Limited to 36 V systems; higher gain reduces base drive sensitivity but increases susceptibility to thermal runaway in linear mode	Select when tighter h_FE tolerance and lower voltage rails justify trade-off in breakdown margin
MMBT3906LT1G	V_CEO = −40 V, f_T = 250 MHz, h_FE = 100–300, identical footprint	Higher speed and lower V_CE(sat) (−0.2 V), but reduced thermal robustness (R_JA = 625 °C/W on FR-5)	Prefer for high-speed switching above 5 MHz; avoid in thermally constrained automotive enclosures where BC856ALT1's 556 °C/W is advantageous

Compared with BC856ALT1, BC857BLT1G offers higher DC gain but sacrifices 20 V of collector-emitter standoff, while MMBT3906LT1G delivers faster switching and lower saturation loss at the cost of reduced thermal margin and narrower safe operating area at elevated temperatures.

Availability

BC856ALT1 is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor conditioning, and medical diagnostic equipment requiring stable component supply, long-term lifecycle support, and AEC-Q101 compliance.

Supply support for BC856ALT1 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 is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BC856ALT1 belongs to onsemi's BC856ALT1G Series of general-purpose PNP transistors engineered for high-reliability discrete signal conditioning and switching in harsh-environment electronics.

FAQ

What is the maximum junction temperature rating for BC856ALT1?

The BC856ALT1 has a specified junction and storage temperature range of −55 °C to +150 °C. This rating allows operation in under-hood automotive environments and industrial enclosures where ambient temperatures exceed 105 °C, provided thermal design maintains T_J ≤ 150 °C using the published R_JA values and derating curves.

Is BC856ALT1 suitable for linear amplification applications?

Yes, BC856ALT1 supports linear amplification with verified h_FE stability across I_C = −0.2 mA to −100 mA and V_CE = −5 V. Its 10 dB noise figure at 1 kHz and normalized gain flatness shown in Figure 1 make it appropriate for low-noise preamplifier stages in sensor signal chains where discrete PNP topology is preferred.

Does BC856ALT1 meet automotive qualification standards?

Yes, BC856ALT1 is AEC-Q101 qualified and PPAP capable, with explicit documentation in the datasheet confirming compliance for automotive applications. The "S" prefix variant (SBC856ALT1G*) is designated for automotive-specific site and control change requirements, but the BC856ALT1 itself carries full AEC-Q101 validation per onsemi's certification records.

What is the typical output capacitance (C_ob) of BC856ALT1 and how does it affect circuit design?

The BC856ALT1 exhibits a typical output capacitance C_ob of 4.5 pF at V_CB = −10 V. This value directly impacts high-frequency roll-off and EMI susceptibility-designers must account for it when placing the device near RF-sensitive nodes or in fast-switching gate-drive paths to avoid unintended resonance or signal distortion.

Can BC856ALT1 be used in high-side switch configurations?

Yes, BC856ALT1 is commonly deployed in high-side switch roles due to its PNP structure: emitter connects to V_CC, collector drives the load to ground, and base is pulled low via a resistor network to enable conduction. Its −65 V V_CEO and −0.3 V V_CE(sat) ensure efficient operation with minimal voltage drop and robust transient handling in such topologies.

BC856ALT1 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:: -

BC856ALT1 FAQ

1.How can I place an order for BC856ALT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for BC856ALT1 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 BC856ALT1 reliable?

The price and inventory of BC856ALT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC856ALT1 is usually 5 days.

3.What payment methods are accepted for BC856ALT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC856ALT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC856ALT1?

BC856ALT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC856ALT1 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 BC856ALT1?

For technical support, including BC856ALT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC856ALT1 requirements.

6.How does Aetrix verify that BC856ALT1 is sourced from the original manufacturer or authorized distributors?

All BC856ALT1 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 BC856ALT1 meets industry standards.

7.What is the process for return or replacement of BC856ALT1?

All BC856ALT1 units undergo pre-shipment inspection (PSI). If there is an issue with BC856ALT1, 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 BC856ALT1 part is unused and in its original packaging.

Return procedure for BC856ALT1:

1.Submit a request within 90 days.

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

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