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

onsemi BCX71JLT1G

Name: BCX71JLT1G
Brand: onsemi
SKU: BCX71JLT1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BCX71JLT1G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

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

Datasheet:: BCX71JLT1G.pdf

Description:: TRANS PNP 45V 0.1A SOT23-3

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Product details

Overview

BCX71JLT1G from onsemi is a PNP silicon general-purpose transistor in SOT-23 package, rated for −45 V_CEO, −100 mA continuous collector current, and 350 mW power dissipation at 25°C. It delivers DC current gain (h_FE) from 40 to 500 across operating conditions and supports low-noise amplifier and switching applications in portable audio, power management, and sensor interface circuits.

For engineers reviewing the BCX71JLT1G datasheet, pinout, applications, or equivalent options, this page provides verified electrical parameters, thermal derating data, noise performance curves, switching timing values, and validated alternative transistors for design-in and BOM optimization.

Technical Context

The BCX71JLT1G operates as a medium-speed, low-power PNP bipolar junction transistor optimized for linear amplification and digital switching. Its h_FE spans 40–500 depending on I_C (2 mA to 50 mA) and V_CE (1 V to 5 V), with V_CE(sat) ≤ −0.55 V at I_C = 50 mA / I_B = 1.25 mA and turn-off time ≤ 800 ns under defined test conditions.

Thermal performance is characterized with R_JA = 357°C/W on a 99.5% alumina substrate (10 × 8 × 0.6 mm), supporting operation from −55°C to +150°C storage and requiring derating of 2.8 mW/°C above 25°C ambient. Noise figure is specified ≤ 6.0 dB at I_C = 0.2 mA, V_CE = −5 V, R_S = 2 kΩ, f = 1 kHz, BW = 200 Hz.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	−45 V - Maximum safe collector-emitter voltage before breakdown; defines rail compatibility in negative-supply circuits.
I_C (cont.)	−100 mA - Continuous collector current limit; sets maximum load drive capability in switching or amplification stages.
P_D @ 25°C	350 mW - Total power dissipation at 25°C ambient; requires thermal derating (2.8 mW/°C) for higher temperatures.
h_FE range	40–500 - DC current gain variation across I_C = 2 mA to 50 mA and V_CE = 1–5 V; impacts bias stability and gain predictability.
V_CE(sat)	≤ −0.55 V @ I_C/I_B = 40 - Saturation voltage defining conduction loss and logic-level compatibility in switch mode.
NF	≤ 6.0 dB @ 1 kHz - Noise figure specifying minimum added noise in low-level analog signal paths like preamplifiers.
t_off	≤ 800 ns - Turn-off delay limiting usable switching frequency in pulse-width modulation or digital logic interfaces.

Pinout & Package

SOT-23 (TO-236) surface-mount package, 3-pin, Pb-free, RoHS-compliant, moisture sensitivity level 1. Dimensions per CASE 318-08: D = 2.80–3.04 mm, E = 1.20–1.40 mm, e = 1.78–2.04 mm, L = 0.10–0.30 mm.

Pin/Terminal	Circuit Role	Design Meaning
1	Base	Current-controlled input node; requires external bias resistor network to set operating point in active or saturation region.
2	Emitter	Common terminal for PNP configuration; connected to higher potential (e.g., V_CC) in typical common-emitter amplifier or switch.
3	Collector	Output terminal sourcing current toward load; polarity must be negative relative to emitter for forward-active operation.

Key Features

Feature	Design Value
Low noise performance	6.0 dB NF at 1 kHz enables use in microphone preamps and sensor signal conditioning without added noise degradation.
High h_FE consistency	h_FE ≥ 100 at I_C = 2 mA ensures stable small-signal gain in bias-sensitive analog stages.
Fast switching	800 ns t_off supports >100 kHz PWM control in LED drivers and DC-DC feedback loops.
Thermal robustness	R_JA = 357°C/W on standard alumina PCB allows reliable operation up to +125°C junction temperature with minimal heatsinking.
Pb-free & RoHS	Halogen-free/BFR-free construction meets global environmental compliance requirements for consumer and industrial end equipment.

Applications

Audio Pre-amplifier Stage	Low-Voltage Switching Load
Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in battery-powered voice recorders. IC Role / Device Role / Timing Role: PNP small-signal amplifier in common-emitter configuration with emitter degeneration for linearity. Use Value: 6.0 dB noise figure and h_FE ≥ 250 at I_C = 2 mA preserve SNR and enable single-stage gain ≥ 100 without cascading.	Use Scenario: Driving 12 V relay coils or LED strings from 3.3 V/5 V microcontroller GPIO pins via level-shifting interface. IC Role / Device Role / Timing Role: Low-side PNP switch controlling current flow from positive rail to grounded load. Use Value: V_CE(sat) ≤ −0.25 V at I_C/I_B = 40 minimizes power loss and heat generation during sustained ON state.
Temperature Sensor Interface	Power Supply Enable Control
Use Scenario: Biasing silicon diode or RTD-based temperature sensing elements in HVAC control modules. IC Role / Device Role / Timing Role: Constant-current source configured with base bias and emitter resistor for precision excitation. Use Value: Tight h_FE tolerance (40–500) and low I_CES (≤ −20 nA at 32 V) ensure stable current output over −40°C to +85°C.	Use Scenario: Enabling/disabling auxiliary 5 V or 3.3 V rails in multi-rail embedded systems based on system wake/sleep states. IC Role / Device Role / Timing Role: High-side PNP pass transistor controlled by MCU output through base resistor network. Use Value: −45 V V_CEO rating provides 2× margin over 24 V supply rails, ensuring long-term reliability under transient overvoltage.

Audio Pre-amplifier Stage

Low-Voltage Switching Load

Use Scenario: Amplifying weak signals from electret microphones or piezoelectric sensors in battery-powered voice recorders.

IC Role / Device Role / Timing Role: PNP small-signal amplifier in common-emitter configuration with emitter degeneration for linearity.

Use Value: 6.0 dB noise figure and h_FE ≥ 250 at I_C = 2 mA preserve SNR and enable single-stage gain ≥ 100 without cascading.

Use Scenario: Driving 12 V relay coils or LED strings from 3.3 V/5 V microcontroller GPIO pins via level-shifting interface.

IC Role / Device Role / Timing Role: Low-side PNP switch controlling current flow from positive rail to grounded load.

Use Value: V_CE(sat) ≤ −0.25 V at I_C/I_B = 40 minimizes power loss and heat generation during sustained ON state.

Temperature Sensor Interface

Power Supply Enable Control

Use Scenario: Biasing silicon diode or RTD-based temperature sensing elements in HVAC control modules.

IC Role / Device Role / Timing Role: Constant-current source configured with base bias and emitter resistor for precision excitation.

Use Value: Tight h_FE tolerance (40–500) and low I_CES (≤ −20 nA at 32 V) ensure stable current output over −40°C to +85°C.

Use Scenario: Enabling/disabling auxiliary 5 V or 3.3 V rails in multi-rail embedded systems based on system wake/sleep states.

IC Role / Device Role / Timing Role: High-side PNP pass transistor controlled by MCU output through base resistor network.

Use Value: −45 V V_CEO rating provides 2× margin over 24 V supply rails, ensuring long-term reliability under transient overvoltage.

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
BC807-25LT1G	Higher h_FE min (250 vs. 40), same SOT-23 package, −45 V V_CEO, −500 mA I_C.	Better suited for higher-current switching where gain stability at low I_C is less critical.	Select when needing guaranteed h_FE ≥ 250 at I_C = 10 mA and higher peak current headroom.
MMBT3906LT1G	Lower V_CEO (−40 V), identical pinout, −200 mA I_C, h_FE 100–300, slightly higher V_CE(sat) (−0.4 V).	Preferred in cost-sensitive designs with <40 V rails and moderate noise requirements.	Choose for legacy-compatible drop-in replacement where −40 V rating suffices and lower cost is prioritized.

Compared with BC807-25LT1G and MMBT3906LT1G, the BCX71JLT1G offers broader h_FE range (40–500) and superior noise performance (6.0 dB), making it optimal for precision analog front-ends and mixed-signal interfaces where gain flexibility and low-noise operation are jointly required.

Availability

BCX71JLT1G is available at Aetrix Electronics and suitable for audio pre-amplifier stages, low-voltage switching loads, and temperature sensor interfaces requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for BCX71JLT1G 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 specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BCX71JLT1G belongs to onsemi's general-purpose bipolar transistor product line, designed for cost-effective, reliable amplification and switching in space-constrained, low-power electronic systems.

FAQ

What is the maximum collector-emitter voltage rating for BCX71JLT1G?

The BCX71JLT1G has a maximum collector-emitter voltage (V_CEO) rating of −45 Vdc. This value is confirmed in the Absolute Maximum Ratings table of the official onsemi datasheet (Rev. 3, August 2009) and defines the upper limit for safe operation in reverse-biased PNP configurations. Exceeding this voltage risks avalanche breakdown and permanent device damage.

Does BCX71JLT1G support low-noise audio applications?

Yes, BCX71JLT1G supports low-noise audio applications with a specified noise figure (NF) of ≤ 6.0 dB at I_C = 0.2 mA, V_CE = −5.0 V, R_S = 2.0 kΩ, f = 1.0 kHz, and BW = 200 Hz. Its noise voltage and current contours (Figures 1–2) confirm suitability for electret microphone preamplifiers and sensor signal chains where SNR preservation is critical.

What is the thermal resistance junction-to-ambient for BCX71JLT1G?

The thermal resistance junction-to-ambient (R_JA) for BCX71JLT1G is 357°C/W, measured with the device mounted on a 99.5% alumina substrate (10 × 8 × 0.6 mm). This value is documented in the Thermal Characteristics section and mandates derating of 2.8 mW/°C above 25°C ambient to maintain safe junction temperature within the −55°C to +150°C storage range.

Is BCX71JLT1G RoHS compliant and lead-free?

Yes, BCX71JLT1G is RoHS compliant and lead-free, as explicitly stated in the Features section of the onsemi datasheet: "These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant." The "M" suffix in the marking diagram and "Pb−free" designation in the Ordering Information further confirm its compliance with EU Directive 2011/65/EU.

What are the pin assignments for BCX71JLT1G in SOT-23 package?

The BCX71JLT1G uses standard SOT-23 pinout: Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector. This mapping is confirmed in the Marking Diagram and Package Dimensions sections of the datasheet (CASE 318, STYLE 6), and matches JEDEC TO-236 outline for consistent PCB layout and assembly across compatible PNP transistors.

BCX71JLT1G 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):: 45 V

Vce Saturation (Max) @ Ib, Ic:: 550mV @ 1.25mA, 50mA

Current - Collector Cutoff (Max):: 20nA

DC Current Gain (hFE) (Min) @ Ic, Vce:: 250 @ 2mA, 5V

Power - Max:: 350 mW

Frequency - Transition:: -

Operating Temperature:: -

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

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

BCX71JLT1G FAQ

1.How can I place an order for BCX71JLT1G through Aetrix?

Please submit a Request for Quotation (RFQ) for BCX71JLT1G 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 BCX71JLT1G reliable?

The price and inventory of BCX71JLT1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BCX71JLT1G is usually 5 days.

3.What payment methods are accepted for BCX71JLT1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BCX71JLT1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BCX71JLT1G?

BCX71JLT1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BCX71JLT1G 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 BCX71JLT1G?

For technical support, including BCX71JLT1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BCX71JLT1G requirements.

6.How does Aetrix verify that BCX71JLT1G is sourced from the original manufacturer or authorized distributors?

All BCX71JLT1G 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 BCX71JLT1G meets industry standards.

7.What is the process for return or replacement of BCX71JLT1G?

All BCX71JLT1G units undergo pre-shipment inspection (PSI). If there is an issue with BCX71JLT1G, 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 BCX71JLT1G part is unused and in its original packaging.

Return procedure for BCX71JLT1G:

1.Submit a request within 90 days.

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

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