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

onsemi BC858ALT1

Name: BC858ALT1
Brand: onsemi
SKU: BC858ALT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BC858ALT1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: BC858ALT1.pdf

Description:: TRANS PNP 30V 0.1A SOT23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BC858ALT1 from onsemi is a PNP silicon general-purpose transistor in SOT-23 package, rated for −30 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 industrial control modules.

For engineers reviewing the BC858ALT1 datasheet, pinout, applications, or equivalent options, key selection criteria include its −30 V collector-emitter breakdown voltage, 125–250 h_FE gain range (at −10 mA), −0.3 V V_CE(sat) at −10 mA/−0.5 mA drive, AEC-Q101 qualification, and Pb-free SOT-23 footprint compatibility with space-constrained PCB layouts.

Technical Context

The BC858ALT1 operates as a discrete PNP bipolar junction transistor optimized for medium-speed switching and analog amplification. Its DC current gain (h_FE) is specified at −10 mA I_C and −5.0 V V_CE, with minimum 125 and maximum 250 - indicating consistent small-signal linearity across production lots. It supports operation from −55°C to +150°C junction temperature.

Thermal performance is defined for FR-5 board (R_JA = 556°C/W) and alumina substrate (R_JA = 417°C/W), enabling thermal-aware design in both standard PCBs and high-reliability ceramic-based assemblies. Switching times are characterized at −3.0 V V_CC, with t_r = 25 ns and t_f = 40 ns, confirming suitability for sub-10 MHz digital signal routing.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−30 V: Maximum safe collector-emitter voltage before breakdown; defines rail-to-rail headroom in negative-supply bias networks.
I_C Continuous	−100 mA: Absolute max DC collector current; sets upper limit for load-driving capability in discrete switch stages.
h_FE	125–250 @ −10 mA/−5 V: Gain range ensures predictable base drive requirements for saturation in logic-level interfacing.
V_CE(sat)	−0.3 V @ −10 mA/−0.5 mA: Low saturation voltage minimizes power loss and improves efficiency in active-low switch configurations.
f_T	100 MHz: Unity-gain bandwidth enables stable amplification up to ~10 MHz with adequate phase margin in emitter-follower buffers.
C_ob	4.5 pF @ −10 V: Output capacitance impacts high-frequency roll-off and rise/fall time in fast-switching nodes.
NF	10 dB @ −0.2 mA/−5 V: Noise figure relevant for low-current preamplifier stages where signal integrity dominates.

Pinout & Package

SOT-23 (TO-236) surface-mount package, 2.90 × 1.30 × 1.00 mm, 3-pin, lead-free, RoHS-compliant. Pin configuration follows Style 6 per onsemi mechanical drawing.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal; requires current-limited drive (typically −0.1 to −5 mA) to bias transistor into active or saturation region.
2	Emiter	Common reference node for PNP operation; connected to higher potential (e.g., V_CC or regulated rail) in typical common-emitter switch.
3	Collector	Output terminal; sinks current to ground or lower-potential node; must remain ≤ −30 V relative to emitter under all operating conditions.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive-grade reliability including temperature cycling, HTRB, and ESD testing - suitable for under-hood and infotainment subsystems.
Pb-free / Halogen-free	Complies with RoHS Directive 2011/65/EU and JEDEC JS709C; eliminates hazardous substances without compromising solderability or thermal performance.
Low V_CE(sat)	−0.3 V at −10 mA/−0.5 mA enables <10 mW dissipation in saturated switch mode - critical for thermally constrained IoT sensor nodes.
High f_T	100 MHz bandwidth supports clean edge reproduction in pulse-width modulation (PWM) gate drivers and clock distribution buffers.
Wide T_J range	−55°C to +150°C operation allows deployment in industrial motor drives, power supply feedback loops, and outdoor metering enclosures.

Applications

Level Shifting	Current Mirror
Use Scenario: Translating TTL/CMOS logic signals between −5 V and 0 V domains in mixed-supply microcontroller peripherals. IC Role / Device Role / Timing Role: PNP switch configured in common-emitter topology to invert and shift logic levels with minimal propagation delay. Use Value: −0.3 V V_CE(sat) ensures output high-state remains within valid input threshold of downstream −5 V logic families.	Use Scenario: Generating matched bias currents for op-amp input stages or ADC reference buffers in precision analog front-ends. IC Role / Device Role / Timing Role: Active current source element paired with identical BC858ALT1 unit to replicate reference current with <5% mismatch. Use Value: Tight h_FE consistency (125–250) and matched thermal coefficients enable <0.5% current tracking over −40°C to +85°C.
Discrete Logic Interface	Load Switching
Use Scenario: Driving LED indicators or optocoupler inputs from 3.3 V MCU GPIO pins in industrial HMIs with negative rail availability. IC Role / Device Role / Timing Role: Active-low switch controlling current path from −5 V rail through indicator load to MCU pin. Use Value: −100 mA I_C rating supports direct drive of 20 mA LEDs with 5× safety margin; 25 ns rise time prevents ghosting in multiplexed displays.	Use Scenario: Enabling/disabling 12 V auxiliary rails in programmable power sequencers for FPGA-based test equipment. IC Role / Device Role / Timing Role: High-side switch controlling power delivery to downstream LDOs or isolated DC-DC converters. Use Value: −30 V V_CEO withstands transient spikes on 12 V bus; 310 ns storage time limits cross-conduction risk during fast turn-off transitions.

Level Shifting

Current Mirror

Use Scenario: Translating TTL/CMOS logic signals between −5 V and 0 V domains in mixed-supply microcontroller peripherals.

IC Role / Device Role / Timing Role: PNP switch configured in common-emitter topology to invert and shift logic levels with minimal propagation delay.

Use Value: −0.3 V V_CE(sat) ensures output high-state remains within valid input threshold of downstream −5 V logic families.

Use Scenario: Generating matched bias currents for op-amp input stages or ADC reference buffers in precision analog front-ends.

IC Role / Device Role / Timing Role: Active current source element paired with identical BC858ALT1 unit to replicate reference current with <5% mismatch.

Use Value: Tight h_FE consistency (125–250) and matched thermal coefficients enable <0.5% current tracking over −40°C to +85°C.

Discrete Logic Interface

Load Switching

Use Scenario: Driving LED indicators or optocoupler inputs from 3.3 V MCU GPIO pins in industrial HMIs with negative rail availability.

IC Role / Device Role / Timing Role: Active-low switch controlling current path from −5 V rail through indicator load to MCU pin.

Use Value: −100 mA I_C rating supports direct drive of 20 mA LEDs with 5× safety margin; 25 ns rise time prevents ghosting in multiplexed displays.

Use Scenario: Enabling/disabling 12 V auxiliary rails in programmable power sequencers for FPGA-based test equipment.

IC Role / Device Role / Timing Role: High-side switch controlling power delivery to downstream LDOs or isolated DC-DC converters.

Use Value: −30 V V_CEO withstands transient spikes on 12 V bus; 310 ns storage time limits cross-conduction risk during fast turn-off transitions.

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	Higher voltage rating and wider gain range; suited for −45 V rail monitoring or higher-gain amplifier stages	Select when system requires >−30 V blocking capability or tighter gain binning for analog matching.
MMBT3906LT1G	V_CEO = −40 V, h_FE = 100–300, same SOT-23 footprint but different gain binning and thermal specs	Broad industry-standard alternative with wider distributor availability but no AEC-Q101 qualification	Choose for non-automotive cost-sensitive designs where automotive qualification is not required.

Compared with BC858ALT1, BC857BLT1G offers higher voltage tolerance and extended gain range at identical footprint, while MMBT3906LT1G provides broader commercial availability but lacks AEC-Q101 validation - making BC858ALT1 the preferred choice for automotive-qualified, −30 V–optimized PNP switching.

Availability

BC858ALT1 is available at Aetrix Electronics and suitable for industrial control systems, automotive body electronics, and precision analog instrumentation requiring stable component supply, long-term lifecycle support, and AEC-Q101 compliance.

Supply support for BC858ALT1 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 electronics, delivering silicon solutions for automotive, industrial, cloud, and IoT applications.

The BC858ALT1 belongs to onsemi's BC856ALT1G Series of general-purpose PNP transistors, designed specifically for reliable, low-cost switching and amplification in space-constrained, thermally demanding environments.

FAQ

What is the maximum collector-emitter voltage rating for BC858ALT1?

The BC858ALT1 has a maximum collector-emitter voltage (V_CEO) rating of −30 V at T_A = 25°C. This rating applies under continuous DC conditions and defines the absolute upper limit for voltage differential between collector and emitter terminals before breakdown occurs. Exceeding this value risks permanent device damage and is strictly prohibited in circuit design.

Is BC858ALT1 qualified for automotive applications?

Yes, BC858ALT1 is AEC-Q101 qualified and PPAP capable, meeting the stress test requirements for automotive electronic components including temperature cycling, highly accelerated life testing (HALT), and electrostatic discharge (ESD) immunity. This makes BC858ALT1 suitable for use in body control modules, lighting drivers, and infotainment power management circuits.

What is the DC current gain (h_FE) range for BC858ALT1 at typical operating conditions?

The BC858ALT1 exhibits a DC current gain (h_FE) range of 125 to 250 when measured at I_C = −10 mA and V_CE = −5.0 V. This gain bin corresponds to the "A" suffix variant within the BC858 series and is verified per onsemi's production test flow - ensuring predictable base drive requirements in linear and switching applications.

Does BC858ALT1 have a Pb-free and RoHS-compliant package?

Yes, BC858ALT1 is supplied in a Pb-free, halogen-free, and RoHS-compliant SOT-23 package, marked with the "G" suffix per onsemi's ordering nomenclature. The device meets EU Directive 2011/65/EU and adheres to JEDEC JS709C standards for environmentally responsible packaging without sacrificing solder joint reliability or thermal performance.

What is the thermal resistance (R_JA) of BC858ALT1 on a standard FR-5 PCB?

On a standard FR-5 printed circuit board (1.0 × 0.75 × 0.062 in), the BC858ALT1 has a junction-to-ambient thermal resistance (R_JA) of 556°C/W at T_A = 25°C. This value decreases linearly by 1.8 mW/°C above 25°C ambient, meaning effective power dissipation must be derated to maintain safe junction temperatures below +150°C.

BC858ALT1 Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: PNP

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

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

Vce Saturation (Max) @ Ib, Ic:: 650mV @ 5mA, 100mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 125 @ 2mA, 5V

Power - Max:: 300 mW

Frequency - Transition:: 100MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3 (TO-236)

BC858ALT1 FAQ

1.How can I place an order for BC858ALT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for BC858ALT1 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 BC858ALT1 reliable?

The price and inventory of BC858ALT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC858ALT1 is usually 5 days.

3.What payment methods are accepted for BC858ALT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC858ALT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC858ALT1?

BC858ALT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC858ALT1 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 BC858ALT1?

For technical support, including BC858ALT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC858ALT1 requirements.

6.How does Aetrix verify that BC858ALT1 is sourced from the original manufacturer or authorized distributors?

All BC858ALT1 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 BC858ALT1 meets industry standards.

7.What is the process for return or replacement of BC858ALT1?

All BC858ALT1 units undergo pre-shipment inspection (PSI). If there is an issue with BC858ALT1, 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 BC858ALT1 part is unused and in its original packaging.

Return procedure for BC858ALT1:

1.Submit a request within 90 days.

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

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