onsemi BF721T1

Overview

BF721T1 from onsemi is a PNP silicon power transistor in SOT-223 package, rated for V_CEO = –300 V, I_C = –50 mA, P_D = 1.5 W, and f_T = 60 MHz, designed for high-voltage switching and linear amplification in industrial power supplies.

For engineers reviewing the BF721T1 datasheet, pinout, applications, or equivalent options, key selection criteria include its –300 V breakdown rating, low V_CE(sat) of –0.8 V at –30 mA/–5 mA drive, thermal resistance of 83.3 °C/W, and RoHS-compliant Pb-free SOT-223 packaging.

Technical Context

This PNP bipolar junction transistor operates with emitter-grounded configuration and supports high-voltage DC switching up to –300 V across collector-emitter and collector-base terminals. Its h_FE ≥ 50 at –25 mA/–20 V ensures stable current amplification in driver stages.

The device features low feedback capacitance (C_re ≤ 1.6 pF) and high f_T, enabling use in medium-frequency amplifier and pulse-switching circuits where gain-bandwidth trade-offs matter. Junction temperature limit is 150 °C with storage range from –65 °C to +150 °C.

Key Specifications

Pinout & Package

SOT-223 (TO-261) surface-mount package with exposed collector tab (pins 2 and 4 internally connected), standardized for thermal and mechanical reliability in power discrete applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJD2955T4G and BC807-40,215, the BF721T1 uniquely balances –300 V capability with SOT-223 thermal performance and medium-frequency response-making it irreplaceable in 200–300 V switching and amplification where both voltage headroom and package efficiency matter.

Availability

BF721T1 is available at Aetrix Electronics and suitable for industrial power supply control, high-voltage signal amplification, DC motor commutation drivers, and overvoltage protection circuits requiring stable component supply and long-term manufacturability.

Supply support for BF721T1 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 focused on energy-efficient innovation for automotive, industrial, cloud, and IoT applications.

The BF721T1 belongs to onsemi's high-voltage bipolar transistor product line, engineered specifically for robustness in offline power conversion, protection circuitry, and medium-frequency analog signal conditioning under elevated voltage stress.

FAQ

What is the maximum collector-emitter voltage rating for BF721T1?

The BF721T1 has a guaranteed minimum V_(BR)CEO of –300 V at I_C = –1.0 mA with base open. This rating applies under DC conditions and defines the absolute upper limit before avalanche breakdown occurs. The BF721T1 must not be operated beyond this voltage in any application, including transient spikes, unless external clamping is implemented per design validation.

Is BF721T1 pin-compatible with BF721T1G?

Yes - BF721T1 and BF721T1G share identical SOT-223 pinout, thermal pad configuration, and electrical specifications. The "G" suffix denotes Pb-free packaging; both variants use the same die and marking layout (AYW/DFG), and are functionally interchangeable in all designs without layout changes.

What is the typical DC current gain (hFE) of BF721T1 at room temperature?

The BF721T1 exhibits h_FE ≥ 50 at I_C = –25 mA and V_CE = –20 V, TA = 25 °C. Gain decreases with rising temperature and collector current - e.g., h_FE drops to ~35 at 125 °C under same bias. Designers should verify gain stability across operating extremes using Figure 1 from the official BF721T1 datasheet.

Can BF721T1 be used in switching power supply topologies?

Yes - the BF721T1 is qualified for switching use in flyback, forward, and active clamp topologies where V_CE stress remains ≤ –300 V. Its –0.8 V V_CE(sat) and 60 MHz f_T support efficient operation up to ~100 kHz switching frequencies. Layout must ensure adequate copper area on pin 2/4 for thermal relief, per the 0.93 in² pad requirement.

Does BF721T1 meet RoHS and halogen-free compliance standards?

Yes - the BF721T1 (and BF721T1G) is certified Pb-free, halogen-free, and BFR-free, complying fully with EU RoHS Directive 2011/65/EU and JEDEC JS709A. The "G" suffix explicitly confirms green packaging; however, even non-G variants (BF721T1) were manufactured to the same environmental specification per onsemi's Rev. 9 datasheet dated September 2010.