onsemi BC447

Overview

BC447 from onsemi is an NPN silicon general-purpose high-voltage transistor in TO-92 package, rated for 80 V_CEO, 300 mA continuous collector current, and 625 mW power dissipation at T_A = 25°C. It delivers h_FE of 50–460 (at I_C = 2–100 mA), V_CE(sat) ≤ 0.25 V, and f_T ≥ 100 MHz - suitable for low-power switching and linear amplification in industrial control interfaces.

For engineers reviewing the BC447 datasheet, pinout, applications, or equivalent options, key selection criteria include its 80 V breakdown rating, TO-92 thermal resistance (R_JA = 200 °C/W), DC current gain spread across operating currents, saturation voltage under 100 mA load, and Pb-free packaging compliance per ON Semiconductor's standard.

Technical Context

The BC447 operates as a discrete NPN bipolar junction transistor optimized for medium-voltage, medium-current switching and analog amplification. Its design supports stable h_FE across I_C = 2–100 mA with V_CE = 5 V, and exhibits low V_CE(sat) (≤ 0.25 V) at I_C/I_B = 10, enabling efficient saturated switching in relay drivers and logic-level translators.

Thermal performance is defined by R_JA = 200 °C/W and R_JC = 83.3 °C/W, with safe operating area limited by second breakdown above 10 V and 50 mA in DC mode. Junction temperature range spans −55°C to +150°C, supporting operation in extended-temperature industrial environments without derating below 25°C ambient.

Key Specifications

Pinout & Package

BC447 is housed in a TO-92 (Case 29, Style 17) through-hole plastic package with 3 leads. Lead spacing is 2.54 mm (0.100"), body height ~4.7 mm, and maximum outline dimensions 5.20 × 5.33 × 4.19 mm (L × W × H). The package is Pb-free and moisture sensitivity level (MSL) 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC547 and PN2222A, BC447 provides superior 80 V breakdown margin for 24–48 V industrial systems while maintaining TO-92 compatibility and cost efficiency - making it the preferred choice where voltage robustness outweighs ultra-high h_FE or case-cooled power handling.

Availability

BC447 is available at Aetrix Electronics and suitable for industrial relay drivers, DC motor speed control, LED current regulation, and signal level translation requiring stable component supply and long-term obsolescence management.

Supply support for BC447 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 manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BC447 belongs to onsemi's legacy high-voltage NPN transistor family designed specifically for reliable, cost-effective switching and amplification in industrial control, power management, and interface circuitry.

FAQ

What is the maximum collector-emitter voltage rating for BC447?

The BC447 has a maximum collector-emitter voltage (V_CEO) rating of 80 Vdc. This value is specified under test conditions of I_C = 1.0 mAdc and I_B = 0, and represents the absolute maximum voltage the device can withstand before breakdown. Exceeding this rating risks permanent damage to the BC447, especially during inductive load switching events.

Does BC447 have a Pb-free package option?

Yes, the BC447G variant is explicitly designated as Pb-free and complies with RoHS Directive 2011/65/EU. The "G" suffix indicates lead-free plating and packaging, and the device retains identical electrical specifications and TO-92 mechanical form factor as the standard BC447. Both versions share MSL Level 1 handling requirements.

What is the DC current gain (h_FE) range for BC447 at typical operating conditions?

The BC447 exhibits h_FE = 50–460 at I_C = 2.0 mAdc and V_CE = 5.0 Vdc, and h_FE = 50–220 at I_C = 10 mAdc under the same V_CE. At I_C = 100 mAdc, h_FE drops to 50–60. This wide gain spread must be accounted for in bias network design to ensure consistent BC447 performance across production lots and temperature ranges.

Can BC447 be used in linear amplifier applications?

Yes, the BC447 supports linear operation with verified h_FE, V_BE(on), and f_T characteristics across I_C = 2–100 mA. Its f_T ≥ 100 MHz and low distortion at moderate signal levels make it suitable for audio preamplifiers, sensor signal conditioning, and low-frequency analog gain stages - provided thermal limits (625 mW at 25°C) and SOA boundaries are respected.

What is the thermal resistance from junction to ambient (R_JA) for BC447 in TO-92 package?

The BC447 has a thermal resistance of R_JA = 200 °C/W when mounted on a standard FR-4 PCB with minimal copper area. This value assumes natural convection cooling and defines how much the junction temperature rises above ambient per milliwatt of dissipated power. For sustained operation near P_D = 625 mW, board-level thermal design (e.g., added copper pour) is strongly recommended to avoid exceeding T_J = 150°C.