Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

Nexperia USA Inc. BC817-40,235

Name: BC817-40,235
Brand: Nexperia USA Inc.
SKU: BC817-40,235
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: BC817-40,235

Manufacturer:: Nexperia USA Inc.

Category:: Single Bipolar Transistors

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

Datasheet:: BC817-40,235.pdf

Description:: TRANS NPN 45V 0.5A TO-236AB

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:58,894

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

BC817-40,235 from Nexperia is a 45 V, 500 mA NPN general-purpose transistor in SOT23 (TO-236AB) package, optimized for linear amplification and switching in low-voltage DC circuits with h_FE = 250–600 at V_CE = 1 V and I_C = 100 mA, used in power supply feedback loops and signal buffering stages.

For engineers reviewing the BC817-40,235 datasheet, BC817-40,235 pinout, BC817-40,235 application, or BC817-40,235 equivalent, key selection criteria include guaranteed h_FE range, thermal resistance (362 K/W on 1 cm² collector pad), V_CE_sat ≤ 700 mV at I_C = 500 mA, and SOT23 footprint compatibility with automated assembly.

Technical Context

This discrete NPN bipolar junction transistor operates in active, saturation, and cutoff regions with base-controlled current amplification. Its h_FE binning (250–600) ensures predictable gain in bias-stable amplifier designs, while V_CEO = 45 V and I_C = 500 mA support robust operation in 24 V industrial control interfaces.

Thermal performance is defined by two derating curves: 250 mW at T_amb ≤ 25 °C on standard FR4, rising to 345 mW with 1 cm² copper pad under collector-enabling higher continuous current in thermally enhanced layouts.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	45 V - Maximum safe collector-emitter voltage before breakdown in open-base configuration; sets upper rail limit for 24 V system switches.
I_C	500 mA - Continuous collector current rating; supports load switching up to ~12 W at 24 V with adequate heatsinking.
h_FE	250–600 - Guaranteed DC current gain at V_CE = 1 V, I_C = 100 mA; enables precise biasing in Class-A amplifiers without gain trimming.
V_CE_sat	≤ 700 mV - Collector-emitter saturation voltage at I_C = 500 mA, I_B = 50 mA; limits conduction loss to < 0.35 W in saturated switch mode.
R_th(j-a)	362 K/W - Thermal resistance junction-to-ambient with 1 cm² collector copper pad; allows ~0.95 °C/W rise per 100 mW dissipation in optimized layout.
f_T	100 MHz - Transition frequency at V_CE = 5 V, I_C = 10 mA; supports small-signal amplification up to ~10 MHz with stable gain margin.
C_c	3 pF - Collector capacitance at V_CB = 10 V; minimizes Miller effect in high-speed switching nodes below 50 MHz.

Pinout & Package

SOT23 (TO-236AB) surface-mount plastic package with 3 leads, 1.3 mm height, and 2.9 mm × 1.3 mm footprint; compatible with standard reflow soldering profiles (JEDEC J-STD-020).

Pin/Terminal	Circuit Role	Design Meaning
1	Base (B)	Current-controlled input node; requires ≥1.2 V forward bias and ≤200 mA peak drive for full saturation.
2	Emitter (E)	Reference terminal for bias network; connects directly to ground or emitter resistor in common-emitter configurations.
3	Collector (C)	High-current output node; electrically tied to PCB copper pour for thermal management in power switching applications.

Key Features

Feature	Design Value
Three h_FE bins	BC817-40 provides 250–600 h_FE, enabling consistent gain matching across production batches without external calibration.
Low V_CE_sat	700 mV max at 500 mA ensures < 0.35 W conduction loss, reducing thermal stress in compact 24 V relay drivers.
High f_T	100 MHz transition frequency supports stable small-signal amplification in sensor front-end stages up to 10 MHz.
Robust thermal rating	345 mW total power dissipation with 1 cm² collector pad enables sustained 400 mA operation in industrial ambient (70 °C).

Applications

Power Supply Feedback

Industrial Sensor Interface

Use Scenario: Amplifying error voltage from TL431 shunt regulator to drive optocoupler LED in isolated AC/DC flyback converters.

IC Role / Device Role / Timing Role: Linear amplifier operating in active region with fixed emitter resistor to set transconductance and loop gain.

Use Value: Tight h_FE tolerance (250–600) maintains consistent loop response across temperature (−55 °C to 150 °C) without compensation.

Use Scenario: Level-shifting and buffering analog output of 0–5 V pressure sensor before ADC input in PLC analog input modules.

IC Role / Device Role / Timing Role: Emitter-follower buffer providing low-output-impedance drive while isolating sensor from ADC sampling transients.

Use Value: 3 pF collector capacitance prevents high-frequency noise coupling into sensitive measurement paths.

24 V Relay Driver

LED Current Limiter

Use Scenario: Switching 24 V, 200 mA coil current for industrial electromechanical relays in motor control panels.

IC Role / Device Role / Timing Role: Saturated switch with base resistor selected to ensure I_B/I_C ≥ 10 for hard saturation and minimal V_CE_sat.

Use Value: 700 mV V_CE_sat limits power loss to 140 mW, allowing operation without heatsink at 70 °C ambient.

Use Scenario: Constant-current source for indicator LEDs in HMI panels using emitter resistor and base bias network.

IC Role / Device Role / Timing Role: Current-regulating element where emitter resistor sets I_C ≈ I_E via V_BE ≈ 0.7 V reference.

Use Value: 250–600 h_FE range ensures ±15% LED current stability despite process variation and temperature drift.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
BC817-40,115	Same electrical specs; differs only in tape-and-reel packaging (10,000 pcs/reel vs. 3,000 pcs/reel for 235 variant) and marking code (6C% with different site code).	No functional difference; suitable for identical circuit roles including relay driving and amplification.	Select 115 for high-volume automated placement requiring larger reels; 235 preferred for prototyping and medium-batch production.
MMBT3904LT1G	Lower h_FE range (100–300), higher V_CE_sat (300 mV typ. but no max spec), same SOT23 package and pinout.	Less suitable for precision gain-critical amplifiers; acceptable for basic switching where gain variation is tolerable.	Choose only if cost sensitivity outweighs gain consistency requirements; verify V_CE_sat margin at I_C = 500 mA in final layout.

Compared with BC817-40,235, the 115 variant offers identical performance in a higher-density reel format, while MMBT3904LT1G trades guaranteed high h_FE and specified V_CE_sat for lower unit cost-making it viable only in non-critical switching roles.

Availability

BC817-40,235 is available at Aetrix Electronics and suitable for industrial control systems, power supply feedback networks, and sensor interface circuits requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for BC817-40,235 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

Nexperia is a global semiconductor expert focused on high-volume, high-reliability discrete and logic devices, with manufacturing rooted in process control and automotive-grade quality systems.

The BC817 series belongs to Nexperia's general-purpose bipolar transistor product line, engineered for cost-sensitive industrial, consumer, and computing applications where robustness, consistency, and SMT manufacturability are prioritized over ultra-high-speed or RF performance.

FAQ

What is the maximum continuous collector current for BC817-40,235 at 70 °C ambient?

At 70 °C ambient temperature with standard FR4 PCB mounting (single-sided copper, tin-plated, standard footprint), the maximum continuous collector current is 375 mA. This is derived from the 250 mW power dissipation limit and the 700 mV V_CE_sat specification, yielding I_C = P_tot/V_CE_sat = 250 mW / 0.7 V ≈ 357 mA, rounded conservatively to 375 mA per Nexperia's published derating curve.

Does BC817-40,235 have automotive qualification?

No, BC817-40,235 is not automotive-qualified. The datasheet explicitly states in Section 13 that this part was changed to non-automotive qualification in Revision 8 (July 2022). For automotive applications, Nexperia offers the BC817-Q series, which undergoes AEC-Q101 testing and includes extended temperature and reliability validation.

How does the h_FE range of BC817-40 compare to BC817-25 and BC817-16?

BC817-40 has an h_FE range of 250–600 at V_CE = 1 V and I_C = 100 mA, BC817-25 is 160–400, and BC817-16 is 100–250. This binning allows designers to select tighter gain distributions: BC817-40 suits precision amplifiers needing high, stable gain; BC817-16 fits simple on/off switching where gain variability is less critical.

Can BC817-40,235 be used in linear regulator pass transistor applications?

Yes, but with thermal constraints. Its 345 mW power dissipation limit on a 1 cm² collector pad allows ~150 mA continuous current at 5 V dropout (P = 5 V × 0.15 A = 750 mW exceeds rating), so it is only viable for low-dropout, low-current linear regulators (< 100 mA) or pulsed operation. For higher currents, discrete MOSFETs or dedicated LDO ICs are recommended.

BC817-40,235 Specifications

Product attributes: Attribute value

Manufacturer:: Nexperia USA Inc.

Series:: -

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

Packaging:: Tape & Reel (TR)

Product Status:: Active

Transistor Type:: NPN

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

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

Vce Saturation (Max) @ Ib, Ic:: 700mV @ 50mA, 500mA

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

DC Current Gain (hFE) (Min) @ Ic, Vce:: 250 @ 100mA, 1V

Power - Max:: 250 mW

Frequency - Transition:: 100MHz

Operating Temperature:: 150°C (TJ)

Grade:: Automotive

Qualification:: AEC-Q101

Mounting Type:: Surface Mount

Supplier Device Package:: TO-236AB

BC817-40,235 FAQ

1.How can I place an order for BC817-40,235 through Aetrix?

Please submit a Request for Quotation (RFQ) for BC817-40,235 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 BC817-40,235 reliable?

The price and inventory of BC817-40,235 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BC817-40,235 is usually 5 days.

3.What payment methods are accepted for BC817-40,235?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BC817-40,235 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BC817-40,235?

BC817-40,235 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BC817-40,235 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 BC817-40,235?

For technical support, including BC817-40,235 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BC817-40,235 requirements.

6.How does Aetrix verify that BC817-40,235 is sourced from the original manufacturer or authorized distributors?

All BC817-40,235 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 BC817-40,235 meets industry standards.

7.What is the process for return or replacement of BC817-40,235?

All BC817-40,235 units undergo pre-shipment inspection (PSI). If there is an issue with BC817-40,235, 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 BC817-40,235 part is unused and in its original packaging.

Return procedure for BC817-40,235:

1.Submit a request within 90 days.

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

Tech Hub

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…

2026-08-11 LDO Regulator: Dropout Voltage, Noise, PSRR and Power Dissipation

LDO regulator guide covering low dropout voltage, power dissipation, thermal design, PSRR, output noise, capacitor stability, adjustable LDO circuits, LDO vs buck converter and datasheet selection chec…

2026-08-06 Conditional Access Module: CAM, CI/CI+ and DVB Security

Conditional Access Module guide covering CAM meaning, CI/CI+ interface, smart card authorization, DVB security workflow, TV and set-top box compatibility, internal electronics, ESD protection, connecto…

2026-08-03 Electronic Component Obsolescence: EOL Risks, Replacement Options and Last-Time Buy Strategy

Guide to electronic component obsolescence covering EOL risk, PCN/PDN notices, last-time buy planning, replacement options, form-fit-function validation, counterfeit risk and BOM lifecycle management.

2026-07-29 18650 Battery: Voltage, Capacity, Charging and Pack Design

18650 battery guide covering lithium-ion cell basics, 3.6V/3.7V voltage, 4.2V charging, mAh and Wh capacity, protected cells, chargers, BMS, series-parallel packs, holders, welding and sourcing checks.…

2026-07-27 Hall Effect Sensor: Working Principle, Types, Circuits and Applications

Hall effect sensor guide covering working principle, linear and digital sensors, Arduino circuits, current sensing, speed detection, automotive applications, A3144 examples, signal filtering and datash…

2026-07-20 Product Change Notification (PCN) in Electronic Components: Meaning and Supply Chain Response

Product Change Notification guide for electronic components, covering PCN meaning, PCN vs PDN/EOL, common change types, risk levels, form-fit-function review, engineering validation, BOM control, LTB/L…

2026-07-19 Blend Door Actuator: Symptoms, Location, Reset and Replacement Guide

A practical guide to blend door actuators, covering HVAC function, symptoms, location, AC and heater issues, reset and calibration, replacement cost, electrical diagnosis, compatibility checks, and rep…

2026-07-17 Raspberry Pi Alternatives: Chip-Level Comparison, Compatibility and Replacement Guide

Engineering guide to Raspberry Pi alternatives, covering chip-level differences, Orange Pi, ROCK, Jetson, Banana Pi, NanoPi, Compute Module, Pico, GPIO, camera, HAT compatibility, and replacement risks…

2026-07-13 How to Test Dynamic Load Response in Low-Voltage High-Current Buck Converters

Engineering guide to dynamic load response testing for high-current buck converters, covering load step setup, slew rate, Vcore undershoot, overshoot, recovery time, probe location, output capacitors a…