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

onsemi BF721T1G

Name: BF721T1G
Brand: onsemi
SKU: BF721T1G
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BF721T1G

Manufacturer:: onsemi

Category:: Single Bipolar Transistors

Package:: TO-261-4, TO-261AA

Datasheet:: BF721T1G.pdf

Description:: TRANS PNP 300V 0.05A SOT223

Quantity:: RFQ Add To RFQ list

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Inventory:9,392

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Product details

Overview

BF721T1G from onsemi is a PNP silicon power transistor in SOT-223 package, rated for V_CEO = –300 V, I_C = –50 mA, and P_D = 1.5 W at T_A = 25°C, designed for high-voltage switching and linear amplification in industrial power supplies and relay drivers.

For engineers reviewing the BF721T1G datasheet, pinout, applications, or equivalent options, key selection criteria include its –300 V breakdown rating, –50 mA continuous collector current, f_T = 60 MHz gain-bandwidth product, low V_CE(sat) of –0.8 V at –30 mA/–5 mA drive, and RoHS-compliant Pb-free SOT-223 packaging.

Technical Context

This PNP bipolar junction transistor operates with emitter-grounded configuration and supports high-voltage off-state blocking up to –300 V across all three breakdown ratings (V_(BR)CEO, V_(BR)CBO, V_(BR)CER). Its h_FE ≥ 50 at –25 mA/–20 V ensures stable DC gain in switching and analog stages.

The device delivers f_T = 60 MHz at –10 mA/–10 V, enabling RF-capable amplification up to UHF range, while C_re = 1.6 pF at –30 V supports fast turn-off in pulse applications. Thermal resistance R_θJA = 83.3°C/W reflects standard SOT-223 board-mount performance.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	–300 V - Enables use in >250 V DC bus switching circuits without derating
I_C	–50 mA - Supports medium-current load control such as solenoid or relay coil drive
P_D	1.5 W - Allows continuous operation at full rating with minimal heatsinking on standard PCB
f_T	60 MHz - Permits stable small-signal amplification up to 30–40 MHz practical bandwidth
V_CE(sat)	–0.8 V @ –30 mA/–5 mA - Minimizes conduction loss in saturated-switching topologies
h_FE	50 min @ –25 mA/–20 V - Ensures predictable base drive requirements in linear and switching designs
C_re	1.6 pF @ –30 V - Reduces Miller effect, supporting clean turn-off in high-speed switching

Pinout & Package

SOT-223 (TO-261) package with 4-pin configuration: pins 2 and 4 are internally connected to collector; pin 1 is base; pin 3 is emitter. Standard surface-mount footprint compatible with automated assembly and thermal pad soldering.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	Base	Control terminal requiring ~–5 mA drive for full saturation at –30 mA collector current
Pins 2 & 4	Collector	High-voltage output node; dual-pin layout improves current handling and thermal path to PCB copper
Pin 3	Emiter	Reference terminal; typically tied to system ground or positive rail in PNP high-side switch configurations

Key Features

Feature	Design Value
Pb-Free, Halogen-Free/BFR-Free	Meets RoHS Directive 2011/65/EU and JEDEC JS709C material compliance
–300 V Breakdown Rating	Supports direct interface with 230 VAC rectified rails or telecom -48 V systems with margin
1.5 W Power Dissipation	Enables operation without external heatsink in ambient temperatures ≤ 70°C on 1-in² copper pad
60 MHz f_T	Validates suitability for broadband preamplifier stages and pulse generator output buffers
Low V_CE(sat)	Reduces power loss to <15 mW at –30 mA, improving efficiency in battery-powered control modules

Applications

Industrial Relay Drivers	High-Voltage DC-DC Bias Circuits
Use Scenario: Driving 24–48 VDC industrial relays with 5–10 mA coil current in PLC output modules. IC Role / Device Role / Timing Role: PNP switch controlling relay coil current path to ground; provides isolation and voltage translation from logic-level microcontroller outputs. Use Value: –300 V V_CEO prevents breakdown during inductive kickback; –0.8 V V_CE(sat) limits self-heating during sustained activation.	Use Scenario: Generating stable bias voltages for gate drivers in isolated flyback or forward converters operating from 300–400 VDC input. IC Role / Device Role / Timing Role: Linear pass element regulating auxiliary supply rail; used with Zener reference and emitter-follower configuration. Use Value: h_FE ≥ 50 ensures predictable current sourcing capability; 150°C T_J rating supports operation near transformer hotspots.
Telecom Line Interface Protection	UHF Signal Amplifiers
Use Scenario: Overvoltage protection clamp in –48 V telecom line cards, absorbing lightning-induced transients up to –300 V. IC Role / Device Role / Timing Role: High-voltage PNP shunt element activated by series Zener or TVS; conducts fault current to ground before downstream IC damage. Use Value: Matched V_(BR)CEO/V_(BR)CBO/V_(BR)CER = –300 V ensures symmetrical clamping behavior under all fault conditions.	Use Scenario: Low-noise preamplifier stage in 30–50 MHz RF receivers for wireless sensor networks. IC Role / Device Role / Timing Role: Common-emitter amplifier with fixed bias network; provides 15–20 dB small-signal gain with minimal distortion. Use Value: f_T = 60 MHz and C_re = 1.6 pF enable stable gain flatness and low phase shift across target band.

Industrial Relay Drivers

High-Voltage DC-DC Bias Circuits

Use Scenario: Driving 24–48 VDC industrial relays with 5–10 mA coil current in PLC output modules.

IC Role / Device Role / Timing Role: PNP switch controlling relay coil current path to ground; provides isolation and voltage translation from logic-level microcontroller outputs.

Use Value: –300 V V_CEO prevents breakdown during inductive kickback; –0.8 V V_CE(sat) limits self-heating during sustained activation.

Use Scenario: Generating stable bias voltages for gate drivers in isolated flyback or forward converters operating from 300–400 VDC input.

IC Role / Device Role / Timing Role: Linear pass element regulating auxiliary supply rail; used with Zener reference and emitter-follower configuration.

Use Value: h_FE ≥ 50 ensures predictable current sourcing capability; 150°C T_J rating supports operation near transformer hotspots.

Telecom Line Interface Protection

UHF Signal Amplifiers

Use Scenario: Overvoltage protection clamp in –48 V telecom line cards, absorbing lightning-induced transients up to –300 V.

IC Role / Device Role / Timing Role: High-voltage PNP shunt element activated by series Zener or TVS; conducts fault current to ground before downstream IC damage.

Use Value: Matched V_(BR)CEO/V_(BR)CBO/V_(BR)CER = –300 V ensures symmetrical clamping behavior under all fault conditions.

Use Scenario: Low-noise preamplifier stage in 30–50 MHz RF receivers for wireless sensor networks.

IC Role / Device Role / Timing Role: Common-emitter amplifier with fixed bias network; provides 15–20 dB small-signal gain with minimal distortion.

Use Value: f_T = 60 MHz and C_re = 1.6 pF enable stable gain flatness and low phase shift across target band.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MJD2955T4G	V_CEO = –60 V, I_C = –10 A, P_D = 15 W - lower voltage rating but higher current/power capacity	Better suited for high-current linear regulators or motor drivers; unsuitable for >–100 V blocking	Select when load current exceeds –50 mA and voltage stress remains below –60 V
BC807-40,215	V_CEO = –45 V, I_C = –500 mA, SOT-23 package - smaller footprint, lower voltage, higher current	Preferred for space-constrained logic-level switching; lacks high-voltage transient robustness	Choose for compact consumer electronics where voltage stress stays below –45 V

Compared with MJD2955T4G and BC807-40,215, the BF721T1G uniquely balances –300 V blocking, –50 mA current, and SOT-223 thermal performance-making it optimal for medium-power, high-voltage industrial signal conditioning where both voltage margin and package manufacturability matter.

Availability

BF721T1G is available at Aetrix Electronics and suitable for industrial relay drivers, telecom line protection circuits, high-voltage DC-DC bias generation, and UHF signal amplifiers requiring stable component supply and long-term lifecycle support.

Supply support for BF721T1G 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 management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and IoT markets.

The BF721T1G belongs to onsemi's high-voltage bipolar transistor product line, engineered for reliability in harsh industrial environments where sustained high-voltage blocking and thermal stability are critical design requirements.

FAQ

What is the maximum collector-emitter voltage rating for BF721T1G?

The BF721T1G has a guaranteed minimum V_(BR)CEO of –300 V at I_C = –1.0 mA and T_A = 25°C. This rating applies under specified test conditions and allows safe operation in circuits with up to –250 V DC working voltage with appropriate safety margin. The BF721T1G maintains this rating across its full operating temperature range.

Is BF721T1G suitable for linear amplification applications?

Yes, the BF721T1G supports linear operation with h_FE ≥ 50 at –25 mA/–20 V and f_T = 60 MHz, enabling stable small-signal amplification up to ~30 MHz. Its low C_re (1.6 pF) and controlled V_CE(sat) support low-distortion performance in emitter-follower and common-emitter configurations when biased within absolute maximum ratings.

What package type does BF721T1G use and how is it mounted?

The BF721T1G uses the SOT-223 (TO-261) surface-mount package, case style 318E. It features four terminals: pins 2 and 4 are internally bonded to the collector, pin 1 is the base, and pin 3 is the emitter. Mounting requires standard reflow profiles for Pb-free solder and benefits from a ≥0.93 in² copper thermal pad per manufacturer note.

Does BF721T1G meet RoHS and environmental compliance standards?

Yes, the BF721T1G is explicitly marked "Pb-Free" and certified RoHS compliant per Directive 2011/65/EU. It is also halogen-free and BFR-free, meeting IPC-1752A material declaration requirements. The "G" suffix in BF721T1G denotes this environmentally compliant packaging variant.

What is the thermal resistance from junction to ambient for BF721T1G?

The BF721T1G has a maximum R_θJA of 83.3°C/W when mounted on a standard 1.575 in × 1.575 in × 0.059 in glass-epoxy PCB with a minimum 0.93 in² copper pad for the collector lead. This value assumes natural convection cooling and defines the worst-case temperature rise per watt dissipated at the die junction.

BF721T1G Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: -

Package/Case:: TO-261-4, TO-261AA

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: PNP

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

Voltage - Collector Emitter Breakdown (Max):: 300 V

Vce Saturation (Max) @ Ib, Ic:: 800mV @ 5mA, 30mA

Current - Collector Cutoff (Max):: 10nA (ICBO)

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

Power - Max:: 1.5 W

Frequency - Transition:: 60MHz

Operating Temperature:: -65°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-223 (TO-261)

BF721T1G FAQ

1.How can I place an order for BF721T1G through Aetrix?

Please submit a Request for Quotation (RFQ) for BF721T1G 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 BF721T1G reliable?

The price and inventory of BF721T1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BF721T1G is usually 5 days.

3.What payment methods are accepted for BF721T1G?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BF721T1G transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BF721T1G?

BF721T1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BF721T1G 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 BF721T1G?

For technical support, including BF721T1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BF721T1G requirements.

6.How does Aetrix verify that BF721T1G is sourced from the original manufacturer or authorized distributors?

All BF721T1G 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 BF721T1G meets industry standards.

7.What is the process for return or replacement of BF721T1G?

All BF721T1G units undergo pre-shipment inspection (PSI). If there is an issue with BF721T1G, 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 BF721T1G part is unused and in its original packaging.

Return procedure for BF721T1G:

1.Submit a request within 90 days.

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

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