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

onsemi BCX19LT1

Name: BCX19LT1
Brand: onsemi
SKU: BCX19LT1
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BCX19LT1

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BCX19LT1.pdf

Description:: TRANS NPN 45V 0.5A SOT23-3

Quantity:: RFQ Add To RFQ list

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Inventory:8,825

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Product details

Overview

BCX19LT1 from ON Semiconductor (formerly Motorola) is a PNP small-signal 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. It serves as a general-purpose switching or linear amplification device in low-power analog and digital interface circuits.

For engineers reviewing the BCX19LT1 datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, 25 V V_CEO, 500 mA continuous collector current, SOT-23 thermal performance (R_θJA = 556 °C/W on FR-5), and verified h_FE range across operating conditions.

Technical Context

The BCX19LT1 operates as a silicon PNP BJT with base-emitter and base-collector junctions optimized for low-to-medium current switching. Its V_CEO = 25 V and V_CBO = 30 V define safe blocking capability in emitter-follower or common-emitter configurations up to 25 V supply rails.

It delivers h_FE ≥ 40 at I_C = 500 mA and V_CE = 1.0 V, with V_CE(sat) ≤ 0.62 V under same conditions - enabling efficient saturation in logic-level driven switch applications. Junction temperature range of –55°C to +150°C supports industrial ambient operation.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	25 V - Maximum collector-emitter voltage before breakdown; sets upper limit for supply rail compatibility in PNP switch designs.
I_C (continuous)	500 mA - Continuous collector current rating; defines max steady-state load drive capability without derating.
h_FE	40–600 - DC current gain range at I_C = 100–500 mA; determines required base drive for saturation or linear biasing.
V_CE(sat)	≤ 0.62 V - Collector-emitter saturation voltage at I_C = 500 mA, I_B = 50 mA; directly impacts conduction loss and power dissipation.
R_θJA	556 °C/W - Thermal resistance junction-to-ambient on FR-5 board; used to calculate max allowable power at given ambient temperature.
T_J, T_stg	–55°C to +150°C - Operating and storage temperature range; confirms suitability for extended industrial environments.

Pinout & Package

SOT-23 (TO-236AB) surface-mount package with 3-pin configuration, JEDEC-compliant footprint, and thermal pad not included. Dimensions: 2.0 × 1.25 × 0.9 mm (L × W × H).

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Control terminal; forward-biased with negative voltage relative to emitter to turn on PNP conduction path.
2	Emiter	Current source terminal; connected to higher potential rail in typical PNP switch configuration.
3	Collector	Current sink terminal; delivers load current to ground or lower-potential node when saturated.

Key Features

Feature	Design Value
PNP polarity	Enables high-side switching topology where emitter connects to V_CC and collector drives load to GND.
Low V_CE(sat)	0.62 V max at full 500 mA ensures <125 mW conduction loss, supporting thermally constrained PCB layouts.
Wide h_FE range	40–600 allows flexible base resistor selection across production lots and temperature extremes.
Industrial temp range	–55°C to +150°C junction rating supports reliability in automotive body control, industrial sensors, and power management modules.

Applications

LED Driver Circuit	Level-Shifting Interface
Use Scenario: Driving 20–100 mA indicator LEDs from 3.3 V or 5 V microcontroller GPIO pins. IC Role / Device Role / Timing Role: PNP switch controlling LED anode connection to V_CC, with base driven low by MCU. Use Value: Low V_CE(sat) minimizes voltage drop across transistor, preserving LED forward voltage margin and brightness consistency.	Use Scenario: Translating 1.8 V logic outputs to 5 V or 12 V domains in mixed-voltage systems. IC Role / Device Role / Timing Role: Active-low level shifter using BCX19LT1 in emitter-follower or common-emitter inverter configuration. Use Value: Verified h_FE > 40 at 100 mA ensures robust switching margin even with marginal base drive or elevated temperature.
Relay Driver Stage	Current Mirror Reference
Use Scenario: Providing base drive to a larger NPN/PNP Darlington pair or directly energizing 5–50 mA relay coils. IC Role / Device Role / Timing Role: Intermediate gain stage isolating MCU output from inductive load transients. Use Value: 500 mA I_C rating and 25 V V_CEO support direct coil drive for miniature relays without external protection diodes in some cases.	Use Scenario: Building matched current sources in analog front-ends or sensor signal conditioning circuits. IC Role / Device Role / Timing Role: One leg of a discrete two-transistor current mirror with matched layout and thermal coupling. Use Value: Tight V_BE(on) = 1.2 V specification and stable h_FE enable predictable mirroring ratio within ±10% over temperature.

LED Driver Circuit

Level-Shifting Interface

Use Scenario: Driving 20–100 mA indicator LEDs from 3.3 V or 5 V microcontroller GPIO pins.

IC Role / Device Role / Timing Role: PNP switch controlling LED anode connection to V_CC, with base driven low by MCU.

Use Value: Low V_CE(sat) minimizes voltage drop across transistor, preserving LED forward voltage margin and brightness consistency.

Use Scenario: Translating 1.8 V logic outputs to 5 V or 12 V domains in mixed-voltage systems.

IC Role / Device Role / Timing Role: Active-low level shifter using BCX19LT1 in emitter-follower or common-emitter inverter configuration.

Use Value: Verified h_FE > 40 at 100 mA ensures robust switching margin even with marginal base drive or elevated temperature.

Relay Driver Stage

Current Mirror Reference

Use Scenario: Providing base drive to a larger NPN/PNP Darlington pair or directly energizing 5–50 mA relay coils.

IC Role / Device Role / Timing Role: Intermediate gain stage isolating MCU output from inductive load transients.

Use Value: 500 mA I_C rating and 25 V V_CEO support direct coil drive for miniature relays without external protection diodes in some cases.

Use Scenario: Building matched current sources in analog front-ends or sensor signal conditioning circuits.

IC Role / Device Role / Timing Role: One leg of a discrete two-transistor current mirror with matched layout and thermal coupling.

Use Value: Tight V_BE(on) = 1.2 V specification and stable h_FE enable predictable mirroring ratio within ±10% over temperature.

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP small-signal transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC807-25	V_CEO = 45 V, h_FE = 160–400 at I_C = 100 mA; otherwise identical SOT-23 pinout and PNP polarity.	Higher voltage headroom enables use in 36 V automotive subsystems where BCX19LT1's 25 V rating is insufficient.	Select BC807-25 when V_CEO > 25 V is required; verify h_FE stability at target I_C since gain profile differs at high current.
MMBT3906	V_CEO = 40 V, I_C = 200 mA, h_FE = 100–300 at I_C = 10 mA; lower current rating than BCX19LT1.	Not suitable for 500 mA loads; best for low-current switching (<100 mA) or bias networks where gain uniformity matters more than current capacity.	Choose MMBT3906 only for sub-200 mA applications where tighter h_FE distribution is prioritized over current handling.

Compared with BCX19LT1, BC807-25 offers higher voltage tolerance but slightly narrower h_FE range at full current, while MMBT3906 trades current capacity for improved gain consistency at low bias - making BCX19LT1 optimal for cost-sensitive 25 V, 500 mA PNP switching where thermal margin on FR-5 is acceptable.

Availability

BCX19LT1 is available at Aetrix Electronics and suitable for LED driver circuits, level-shifting interfaces, relay driver stages, and current mirror references requiring stable component supply and industrial-grade temperature performance.

Supply support for BCX19LT1 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 electronics, with roots in Motorola's semiconductor division and expertise in discrete devices, power management, and signal processing ICs.

The BCX19LT1 belongs to ON Semiconductor's legacy small-signal transistor family designed for cost-effective, reliable PNP switching and amplification in consumer, industrial, and automotive auxiliary systems.

FAQ

What is the maximum collector-emitter voltage rating for BCX19LT1?

The BCX19LT1 has a maximum collector-emitter voltage (V_CEO) rating of 25 V DC, as specified in the Motorola Small-Signal Transistors Device Data sheet. This value is measured with I_C = 10 mA and I_B = 0. Exceeding this voltage risks avalanche breakdown and permanent device damage. The BCX19LT1 must not be used in circuits where V_CE may transiently exceed 25 V, even briefly.

Is BCX19LT1 a PNP or NPN transistor?

The BCX19LT1 is a PNP bipolar junction transistor. Its pinout (Base=Pin1, Emitter=Pin2, Collector=Pin3) and electrical characteristics-including negative voltage polarities for V_CEO, V_CBO, and V_BE(on)-confirm PNP operation. In circuit design, the emitter connects to a higher potential than the collector, and the base is driven negative relative to the emitter to achieve conduction.

What is the DC current gain (h_FE) range for BCX19LT1 at 500 mA collector current?

At I_C = 500 mA and V_CE = 1.0 V, the BCX19LT1 exhibits h_FE ranging from 40 (minimum) to 600 (maximum), per the Electrical Characteristics table in the official datasheet. This wide spread reflects process variation and requires design margining in base drive calculations - especially critical in saturation-critical switching applications.

Can BCX19LT1 replace BCX17LT1 in a circuit?

No, BCX19LT1 is not a direct replacement for BCX17LT1 due to differing voltage ratings: BCX17LT1 has V_CEO = 45 V and V_CBO = 50 V, while BCX19LT1 is rated at 25 V and 30 V respectively. Substituting BCX19LT1 in a BCX17LT1 design risks premature breakdown if collector-emitter voltage exceeds 25 V. Always verify voltage stress margins before interchanging these parts.

What is the thermal resistance (R_θJA) of BCX19LT1 on a standard FR-5 PCB?

The BCX19LT1 has a junction-to-ambient thermal resistance (R_θJA) of 556 °C/W when mounted on a standard FR-5 printed circuit board (1.0 × 0.75 × 0.062 in.) at T_A = 25°C. This value assumes the recommended SOT-23 footprint and defines the temperature rise per milliwatt of dissipated power - critical for calculating safe operating area in continuous-duty applications.

BCX19LT1 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:: NPN

Current - Collector (Ic) (Max):: 500 mA

Voltage - Collector Emitter Breakdown (Max):: 45 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)

BCX19LT1 FAQ

1.How can I place an order for BCX19LT1 through Aetrix?

Please submit a Request for Quotation (RFQ) for BCX19LT1 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 BCX19LT1 reliable?

The price and inventory of BCX19LT1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BCX19LT1 is usually 5 days.

3.What payment methods are accepted for BCX19LT1?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BCX19LT1 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BCX19LT1?

BCX19LT1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BCX19LT1 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 BCX19LT1?

For technical support, including BCX19LT1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BCX19LT1 requirements.

6.How does Aetrix verify that BCX19LT1 is sourced from the original manufacturer or authorized distributors?

All BCX19LT1 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 BCX19LT1 meets industry standards.

7.What is the process for return or replacement of BCX19LT1?

All BCX19LT1 units undergo pre-shipment inspection (PSI). If there is an issue with BCX19LT1, 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 BCX19LT1 part is unused and in its original packaging.

Return procedure for BCX19LT1:

1.Submit a request within 90 days.

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

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