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

onsemi BCX18LT1G

Name: BCX18LT1G
Brand: onsemi
SKU: BCX18LT1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BCX18LT1G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BCX18LT1G.pdf

Description:: TRANS PNP 25V 0.5A SOT23-3

Quantity:: RFQ Add To RFQ list

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Product details

Overview

BCX18LT1G from onsemi is a PNP general-purpose bipolar junction transistor in SOT-23 package, rated for V_CEO = 25 V, I_C = 500 mA, and h_FE = 40–600 (at I_C = 500 mA, V_CE = 1.0 V). It operates across −55 °C to +150 °C and is used in low-voltage switching and amplification circuits such as LED drivers and signal inversion stages.

For engineers reviewing the BCX18LT1G datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, SOT-23 footprint compatibility, guaranteed h_FE range at high current, V_CE(sat) ≤ 0.62 V, and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

The BCX18LT1G is a silicon planar epitaxial PNP transistor optimized for medium-current linear and switching applications. Its design supports stable DC current gain across I_C = 100–500 mA with V_CE = 1.0 V bias, and features low saturation voltage under forced β = 10 conditions (I_C/I_B = 10).

Thermal performance is defined for both FR-5 and alumina substrates: R_JA = 556 °C/W on FR-5 and 417 °C/W on alumina, enabling use in compact PCB layouts with controlled power dissipation up to 225 mW (FR-5) or 300 mW (alumina) at 25 °C ambient.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25 V - Maximum collector-emitter voltage before breakdown under open-base condition; defines safe operating voltage headroom in PNP switch configurations.
I_C	500 mA - Continuous collector current rating; supports load switching up to ~0.5 A with appropriate heatsinking or board thermal management.
h_FE	40–600 - DC current gain range at I_C = 500 mA, V_CE = 1.0 V; enables predictable base drive sizing for saturated switching or linear amplification.
V_CE(sat)	≤ 0.62 V - Collector-emitter saturation voltage at I_C = 500 mA, I_B = 50 mA; ensures low conduction loss and minimal self-heating in on-state operation.
T_J	−55 °C to +150 °C - Junction temperature range; validates suitability for under-hood automotive, industrial control, and extended-temperature embedded systems.
Pb-Free/RoHS	Yes - Halogen-free, BFR-free, and RoHS-compliant packaging; meets global environmental compliance requirements without derating.

Pinout & Package

SOT-23 (TO-236) plastic surface-mount package, 3-pin, small-outline transistor case 318-08, style 6. Marking "T2" on top surface. Dimensions per ON Semiconductor specification: D = 2.80–3.04 mm, E = 1.20–1.40 mm, pitch = 1.90 mm.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal for forward-biased PNP operation; requires negative bias relative to emitter to enable conduction.
2	Emitter	Current source terminal in PNP configuration; connected to higher potential rail (e.g., V_CC) in common-emitter switch layouts.
3	Collector	Current sink terminal; delivers load current to ground or lower-potential node when transistor is biased on.

Key Features

Feature	Design Value
AEC-Q101 qualified	Validated for automotive applications including engine control modules and body electronics where reliability under thermal cycling and vibration is critical.
Low V_CE(sat)	0.62 V max at I_C = 500 mA ensures <120 mW conduction loss, reducing thermal stress in space-constrained PCBs.
Wide h_FE range	40–600 at I_C = 500 mA allows robust base drive design across manufacturing lot variations without recalibration.
High-temperature operation	Rated to +150 °C junction temperature supports use in sealed enclosures or near heat-generating components.

Applications

LED Driver Circuit	Signal Level Shifter
Use Scenario: Driving 20–50 mA indicator LEDs from microcontroller GPIO pins with 3.3 V or 5 V supply rails. IC Role / Device Role / Timing Role: PNP switch controlling current path from V_CC to LED anode; emitter tied to V_CC, collector to LED cathode. Use Value: Low V_CE(sat) minimizes voltage drop across BCX18LT1G, preserving >2.8 V across LED for consistent brightness at 500 mA capability.	Use Scenario: Translating logic-high signals from 3.3 V MCU to 5 V or 12 V peripheral inputs requiring active-low enable. IC Role / Device Role / Timing Role: Inverting level shifter with emitter at target rail (e.g., 5 V), base driven by MCU output, collector pulled up to same rail. Use Value: Guaranteed h_FE ≥ 40 at 500 mA ensures reliable saturation even with weak MCU drive, eliminating need for external pull-up resistors in many cases.
Automotive Door Module	Industrial Sensor Interface
Use Scenario: Controlling small solenoids or relays (<300 mA) in vehicle door lock actuators under AEC-Q101 environmental stress. IC Role / Device Role / Timing Role: Final-stage PNP driver stage interfacing between ASIC gate driver and inductive load. Use Value: AEC-Q101 qualification and −55 °C to +150 °C rating ensure functional integrity during cold cranking and under-hood thermal transients.	Use Scenario: Amplifying low-level analog sensor outputs (e.g., thermistor divider, RTD bridge) into buffered voltage signals for ADC input. IC Role / Device Role / Timing Role: Common-emitter amplifier with fixed bias network; configured for unity or modest gain with stable h_FE at 100–300 mA. Use Value: Tight h_FE min/max spread at mid-current enables predictable gain calibration and reduced drift over temperature vs. wide-tolerance alternatives.

LED Driver Circuit

Signal Level Shifter

Use Scenario: Driving 20–50 mA indicator LEDs from microcontroller GPIO pins with 3.3 V or 5 V supply rails.

IC Role / Device Role / Timing Role: PNP switch controlling current path from V_CC to LED anode; emitter tied to V_CC, collector to LED cathode.

Use Value: Low V_CE(sat) minimizes voltage drop across BCX18LT1G, preserving >2.8 V across LED for consistent brightness at 500 mA capability.

Use Scenario: Translating logic-high signals from 3.3 V MCU to 5 V or 12 V peripheral inputs requiring active-low enable.

IC Role / Device Role / Timing Role: Inverting level shifter with emitter at target rail (e.g., 5 V), base driven by MCU output, collector pulled up to same rail.

Use Value: Guaranteed h_FE ≥ 40 at 500 mA ensures reliable saturation even with weak MCU drive, eliminating need for external pull-up resistors in many cases.

Automotive Door Module

Industrial Sensor Interface

Use Scenario: Controlling small solenoids or relays (<300 mA) in vehicle door lock actuators under AEC-Q101 environmental stress.

IC Role / Device Role / Timing Role: Final-stage PNP driver stage interfacing between ASIC gate driver and inductive load.

Use Value: AEC-Q101 qualification and −55 °C to +150 °C rating ensure functional integrity during cold cranking and under-hood thermal transients.

Use Scenario: Amplifying low-level analog sensor outputs (e.g., thermistor divider, RTD bridge) into buffered voltage signals for ADC input.

IC Role / Device Role / Timing Role: Common-emitter amplifier with fixed bias network; configured for unity or modest gain with stable h_FE at 100–300 mA.

Use Value: Tight h_FE min/max spread at mid-current enables predictable gain calibration and reduced drift over temperature vs. wide-tolerance alternatives.

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
BCX17LT1G	V_CEO = 45 V (vs. 25 V), same SOT-23 package and pinout; h_FE min = 100 at I_C = 100 mA.	Better suited for higher-voltage switching (e.g., 36 V automotive systems); less optimal for low-V_CE saturation-critical designs due to higher V_CE(sat).	Select BCX17LT1G when system voltage exceeds 25 V but load current remains ≤500 mA.
MMBT3906LT1G	V_CEO = 40 V, I_C = 200 mA (vs. 500 mA); h_FE = 100–300 at I_C = 10 mA; smaller thermal mass.	Lower current capability limits use to signal-level loads only; not suitable for ≥300 mA switching or driving moderate-power LEDs.	Choose MMBT3906LT1G for cost-sensitive, low-current logic inversion where thermal margin is not constrained.

Compared with BCX17LT1G and MMBT3906LT1G, the BCX18LT1G uniquely balances 25 V voltage rating, 500 mA current handling, and low 0.62 V saturation voltage-making it optimal for medium-current, low-drop PNP switching in space-limited automotive and industrial PCBs.

Availability

BCX18LT1G is available at Aetrix Electronics and suitable for automotive body electronics, industrial sensor interfaces, and LED lighting control requiring stable component supply, AEC-Q101 compliance, and SOT-23 footprint consistency.

Supply support for BCX18LT1G 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 delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BCX18LT1G belongs to onsemi's general-purpose bipolar transistor family designed for cost-effective, reliable switching and amplification in high-volume consumer, industrial, and automotive electronics.

FAQ

What is the maximum continuous collector current for BCX18LT1G?

The BCX18LT1G is rated for a maximum continuous collector current (I_C) of 500 mA at T_A = 25 °C on FR-5 board. Derating applies above 25 °C at 1.8 mW/°C. This rating assumes proper PCB thermal design and is validated per the manufacturer's thermal characteristics table in the official BCX18LT1G datasheet.

Is BCX18LT1G suitable for automotive applications?

Yes, BCX18LT1G is AEC-Q101 qualified and PPAP capable, making it suitable for automotive applications including body control modules, lighting drivers, and sensor interfaces. Its −55 °C to +150 °C junction temperature range and Pb-free, halogen-free construction meet stringent automotive reliability and environmental standards required for under-hood and cabin systems.

What is the pin configuration of BCX18LT1G in the SOT-23 package?

The BCX18LT1G uses standard SOT-23 pinout: Pin 1 is Base, Pin 2 is Emitter, and Pin 3 is Collector. This matches the marking diagram and mechanical drawing in the BCX18LT1G datasheet (Case 318-08, Style 6). The device is marked "T2" on the top surface, confirming its identity within the BCX17/18/19 series.

Does BCX18LT1G have a specified V_CE(sat) value?

Yes, the BCX18LT1G specifies V_CE(sat) ≤ 0.62 V at I_C = 500 mA and I_B = 50 mA (forced β = 10), per the Electrical Characteristics table in the official datasheet. This value is measured at T_A = 25 °C and defines the upper bound of conduction loss in saturated switching applications using BCX18LT1G.

How does BCX18LT1G differ from BCX19LT1G?

The BCX18LT1G is a PNP transistor rated for V_CEO = 25 V and I_C = 500 mA, while BCX19LT1G is its NPN counterpart with V_CEO = 45 V and identical SOT-23 package. Their complementary polarity, different breakdown voltages, and distinct h_FE curves mean they are not interchangeable without circuit redesign-BCX18LT1G serves high-side switch roles, BCX19LT1G suits low-side configurations.

BCX18LT1G 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):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 25 V

Vce Saturation (Max) @ Ib, Ic:: 620mV @ 50mA, 500mA

Current - Collector Cutoff (Max):: 100nA (ICBO)

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 100mA, 1V

Power - Max:: 300 mW

Frequency - Transition:: -

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

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

BCX18LT1G FAQ

1.How can I place an order for BCX18LT1G through Aetrix?

Please submit a Request for Quotation (RFQ) for BCX18LT1G 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 BCX18LT1G reliable?

The price and inventory of BCX18LT1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BCX18LT1G is usually 5 days.

3.What payment methods are accepted for BCX18LT1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BCX18LT1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BCX18LT1G?

BCX18LT1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BCX18LT1G 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 BCX18LT1G?

For technical support, including BCX18LT1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BCX18LT1G requirements.

6.How does Aetrix verify that BCX18LT1G is sourced from the original manufacturer or authorized distributors?

All BCX18LT1G 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 BCX18LT1G meets industry standards.

7.What is the process for return or replacement of BCX18LT1G?

All BCX18LT1G units undergo pre-shipment inspection (PSI). If there is an issue with BCX18LT1G, 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 BCX18LT1G part is unused and in its original packaging.

Return procedure for BCX18LT1G:

1.Submit a request within 90 days.

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

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