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

onsemi BF422RL1G

Name: BF422RL1G
Brand: onsemi
SKU: BF422RL1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: BF422RL1G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-226-3, TO-92-3 Long Body, Formed Leads

Datasheet:: BF422RL1G.pdf

Description:: TRANS NPN 250V 0.05A TO92

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:6,782

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

Product details

Overview

BF422RL1G from onsemi is an NPN silicon high-voltage transistor designed for switching and amplification in off-line power supplies, CRT horizontal deflection, and pulse applications. It features V_CEO = 250 V, I_C = 50 mA continuous, h_FE ≥ 50 at 25 mA/20 V, f_T = 60 MHz, and TO-92 package with Pb-free finish.

For engineers reviewing the BF422RL1G datasheet, pinout, applications, or equivalent options, key selection criteria include high-voltage blocking capability (250 V), low saturation voltage (V_CE(sat) ≤ 0.5 V), thermal resistance (R_JA = 150 °C/W), and compatibility with tape-and-reel automated assembly.

Technical Context

This device operates as a general-purpose NPN bipolar junction transistor optimized for high-voltage switching where fast turn-off and stable gain at elevated collector-emitter voltages are required. Its breakdown ratings (V_CEO = 250 V, V_CBO = 250 V) and low leakage (I_CBO ≤ 10 nA) support reliable operation in flyback snubber circuits and line-scan drivers.

The BF422RL1G delivers DC current gain ≥50 under standard bias (I_C = 25 mA, V_CE = 20 V), with f_T = 60 MHz enabling use in medium-frequency pulse amplification. Its thermal design (R_JL = 68 °C/W) supports mounting on FR4 with 200 mm² copper for sustained 830 mW dissipation at 25°C ambient.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	250 V - Sustains 250 V between collector and emitter before breakdown; suitable for 220 VAC-derived supply rails with margin.
I_C (continuous)	50 mA - Maximum steady-state collector current; defines safe operating area for continuous switching loads.
h_FE	≥50 - Minimum DC current gain at 25 mA/20 V; ensures predictable base drive requirements in linear or saturated switch modes.
f_T	60 MHz - Current-gain bandwidth product; enables stable amplification up to ~10–20 MHz in common-emitter configurations.
V_CE(sat)	≤0.5 V - Collector-emitter saturation voltage at I_C/I_B = 10; minimizes conduction loss in switching applications.
R_JA	150 °C/W - Junction-to-ambient thermal resistance on FR4 with 200 mm² copper; determines temperature rise under power dissipation.

Pinout & Package

BF422RL1G is housed in a TO-92 (Case 29, Style 14) plastic package with Pb-free finish, lead-forming option for tape-and-reel (RL1), and standardized pinout: Pin 1 = Emitter, Pin 2 = Collector, Pin 3 = Base.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Emitter	Current exit path; referenced to ground or low-side return in common-emitter configurations.
Pin 2	Collector	High-voltage input/output node; connects to primary-side switching node in flyback or deflection circuits.
Pin 3	Base	Control terminal; requires current-limited drive (e.g., resistor-coupled) to achieve target I_C with defined h_FE.

Key Features

Feature	Design Value
High V_CEO rating	250 V enables direct interface with rectified 220 VAC mains without additional voltage division or clamping.
Pb-free TO-92 package	Complies with RoHS Directive 2011/65/EU and supports lead-free reflow soldering per J-STD-020.
Low V_CE(sat)	≤0.5 V at I_C = 20 mA reduces power loss and self-heating during saturation in switching regulators.
Stable h_FE over temperature	h_FE maintained across −55°C to +125°C junction range, supporting industrial-grade timing and control circuits.

Applications

Switch-Mode Power Supply Snubber	CRT Horizontal Deflection Driver
Use Scenario: Absorbs voltage spikes across primary-side MOSFETs in flyback converters using RCD clamp networks. IC Role / Device Role / Timing Role: High-voltage NPN switch that conducts transient energy into snubber capacitor during MOSFET turn-off. Use Value: Withstands 250 V repetitive peaks and exhibits low leakage (I_CBO ≤ 10 nA), ensuring minimal standby loss and long-term reliability.	Use Scenario: Drives flyback transformer primary in analog CRT monitors requiring precise horizontal scan timing. IC Role / Device Role / Timing Role: Linear amplifier and fast-switching transistor controlling sawtooth current waveform generation. Use Value: 60 MHz f_T and stable h_FE ensure accurate pulse edge fidelity and consistent deflection amplitude across temperature.
DC-DC Converter Auxiliary Bias	Industrial Relay Driver
Use Scenario: Provides isolated auxiliary V_CC for PWM controller ICs in offline AC-DC adapters. IC Role / Device Role / Timing Role: Secondary-side NPN pass transistor regulating feedback winding output to fixed 12–15 V rail. Use Value: V_CEO = 250 V allows direct connection to high-voltage secondary windings; low V_CE(sat) maintains regulation accuracy under load.	Use Scenario: Interfaces microcontroller GPIOs to 24 VDC industrial relays in PLC I/O modules. IC Role / Device Role / Timing Role: Low-side switch enabling relay coil energization with controlled turn-on/turn-off timing. Use Value: h_FE ≥ 50 ensures single-stage drive from 3.3 V or 5 V logic; TO-92 footprint simplifies layout in space-constrained DIN-rail enclosures.

Switch-Mode Power Supply Snubber

CRT Horizontal Deflection Driver

Use Scenario: Absorbs voltage spikes across primary-side MOSFETs in flyback converters using RCD clamp networks.

IC Role / Device Role / Timing Role: High-voltage NPN switch that conducts transient energy into snubber capacitor during MOSFET turn-off.

Use Value: Withstands 250 V repetitive peaks and exhibits low leakage (I_CBO ≤ 10 nA), ensuring minimal standby loss and long-term reliability.

Use Scenario: Drives flyback transformer primary in analog CRT monitors requiring precise horizontal scan timing.

IC Role / Device Role / Timing Role: Linear amplifier and fast-switching transistor controlling sawtooth current waveform generation.

Use Value: 60 MHz f_T and stable h_FE ensure accurate pulse edge fidelity and consistent deflection amplitude across temperature.

DC-DC Converter Auxiliary Bias

Industrial Relay Driver

Use Scenario: Provides isolated auxiliary V_CC for PWM controller ICs in offline AC-DC adapters.

IC Role / Device Role / Timing Role: Secondary-side NPN pass transistor regulating feedback winding output to fixed 12–15 V rail.

Use Value: V_CEO = 250 V allows direct connection to high-voltage secondary windings; low V_CE(sat) maintains regulation accuracy under load.

Use Scenario: Interfaces microcontroller GPIOs to 24 VDC industrial relays in PLC I/O modules.

IC Role / Device Role / Timing Role: Low-side switch enabling relay coil energization with controlled turn-on/turn-off timing.

Use Value: h_FE ≥ 50 ensures single-stage drive from 3.3 V or 5 V logic; TO-92 footprint simplifies layout in space-constrained DIN-rail enclosures.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage NPN transistor applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
BF420RL1G	V_CEO = 300 V (vs. 250 V); otherwise identical pinout, package, and gain specs.	Suitable for designs requiring higher voltage margin (e.g., 277 VAC lighting systems).	Select BF420RL1G when >250 V blocking is mandatory; BF422RL1G preferred for cost-sensitive 220–240 VAC designs.
MPSA42RL1G	Same V_CEO = 300 V, but h_FE min = 40 (vs. 50); slightly higher V_CE(sat) (0.75 V typical).	Acceptable where lower gain or higher saturation voltage is tolerable in non-critical switching.	Use MPSA42RL1G only if existing BOM uses it; BF422RL1G offers tighter gain spec and lower V_CE(sat) for improved efficiency.

Compared with BF420RL1G and MPSA42RL1G, BF422RL1G provides the optimal balance of 250 V rating, guaranteed h_FE ≥ 50, and low V_CE(sat) ≤ 0.5 V-making it ideal for cost-sensitive, thermally constrained high-voltage switching where precise gain control matters.

Availability

BF422RL1G is available at Aetrix Electronics and suitable for switch-mode power supplies, CRT deflection circuits, and industrial relay drivers requiring stable component supply, RoHS-compliant packaging, and tape-and-reel delivery for SMT placement.

Supply support for BF422RL1G 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 BF422RL1G belongs to onsemi's high-voltage bipolar transistor family, engineered specifically for robust switching in off-line power conversion, display deflection, and industrial control systems where reliability under high-voltage stress is critical.

FAQ

What is the maximum collector-emitter voltage rating for BF422RL1G?

The BF422RL1G has a maximum collector-emitter voltage (V_CEO) rating of 250 Vdc. This value is tested with I_C = 1.0 mA and I_B = 0, and represents the highest voltage the device can block in common-emitter configuration without breakdown. Exceeding this rating risks permanent damage, so designs must include appropriate derating margins-especially in inductive switching applications where voltage spikes may occur.

Is BF422RL1G compatible with lead-free reflow soldering processes?

Yes, BF422RL1G is Pb-free and qualified for lead-free reflow soldering per J-STD-020. Its TO-92 package meets RoHS Directive 2011/65/EU requirements. The device supports peak reflow temperatures up to 260°C for 30 seconds, and its thermal characteristics-including R_JL = 68 °C/W-are validated under Pb-free assembly conditions. Always verify profile compliance using onsemi's official soldering guidelines.

What is the DC current gain (h_FE) specification for BF422RL1G?

The BF422RL1G guarantees a minimum DC current gain (h_FE) of 50 when tested at I_C = 25 mA and V_CE = 20 Vdc at 25°C ambient. This parameter is critical for calculating base drive requirements in switching or linear amplifier designs. Note that h_FE varies with temperature and operating point-onsemi's datasheet shows curves from −55°C to +125°C, confirming usable gain across industrial temperature ranges.

Does BF422RL1G have a specified current-gain bandwidth product (f_T)?

Yes, BF422RL1G has a typical current-gain bandwidth product (f_T) of 60 MHz, measured at I_C = 10 mA, V_CE = 10 Vdc, and f = 20 MHz. This metric indicates the frequency at which small-signal current gain drops to unity, defining the upper limit for useful amplification or high-speed switching. Designers should consult the f_T vs. I_C curve in the BF422RL1G datasheet to confirm performance at their specific bias point.

What are the thermal resistance values for BF422RL1G?

BF422RL1G has a junction-to-ambient thermal resistance (R_JA) of 150 °C/W when mounted on a standard FR4 board with 200 mm² of 1 oz copper and 5 mm lead length. Its junction-to-lead resistance (R_JL) is 68 °C/W. These values define temperature rise under power dissipation: for example, at 500 mW dissipation, junction temperature rises ~75°C above ambient. PCB layout and copper area directly impact actual R_JA, so thermal validation is required per application.

BF422RL1G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-226-3, TO-92-3 Long Body, Formed Leads

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Current - Collector (Ic) (Max):: 50 mA

Voltage - Collector Emitter Breakdown (Max):: 250 V

Vce Saturation (Max) @ Ib, Ic:: 500mV @ 2mA, 20mA

Current - Collector Cutoff (Max):: -

DC Current Gain (hFE) (Min) @ Ic, Vce:: 50 @ 25mA, 20V

Power - Max:: 830 mW

Frequency - Transition:: 60MHz

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92 (TO-226)

BF422RL1G FAQ

1.How can I place an order for BF422RL1G through Aetrix?

Please submit a Request for Quotation (RFQ) for BF422RL1G 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 BF422RL1G reliable?

The price and inventory of BF422RL1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BF422RL1G is usually 5 days.

3.What payment methods are accepted for BF422RL1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BF422RL1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BF422RL1G?

BF422RL1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BF422RL1G 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 BF422RL1G?

For technical support, including BF422RL1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BF422RL1G requirements.

6.How does Aetrix verify that BF422RL1G is sourced from the original manufacturer or authorized distributors?

All BF422RL1G 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 BF422RL1G meets industry standards.

7.What is the process for return or replacement of BF422RL1G?

All BF422RL1G units undergo pre-shipment inspection (PSI). If there is an issue with BF422RL1G, 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 BF422RL1G part is unused and in its original packaging.

Return procedure for BF422RL1G:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…