onsemi BC212B

Overview

BC212B from ON Semiconductor is a PNP silicon small-signal amplifier transistor in TO-92 package, rated for −50 V_CEO, −100 mA_C, 350 mW at T_A = 25°C, with DC current gain (h_FE) of 40–120 at I_C = −10 mA and f_T = 280 MHz - used in low-noise audio preamplifier stages and general-purpose switching circuits.

For engineers reviewing the BC212B datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, TO-92 mechanical compatibility, −50 V breakdown rating, 280 MHz f_T, and 10 dB noise figure at 1 kHz - critical for analog signal conditioning and discrete gain block design.

Technical Context

The BC212B operates as a medium-speed, low-noise PNP bipolar junction transistor optimized for linear amplification and switching in ambient-temperature-stable circuits. Its h_FE spans 40–120 across collector currents from −2 mA to −100 mA, and its f_T of 280 MHz supports RF front-end and wideband audio applications up to ~100 MHz.

Thermal performance is defined by R_JA = 357°C/W and R_JC = 125°C/W, enabling operation up to +150°C junction temperature. Saturation voltage V_CE(sat) reaches −0.25 V at I_C = −100 mA / I_B = −5 mA, supporting efficient active-mode biasing in discrete amplifier topologies.

Key Specifications

Pinout & Package

BC212B is housed in a through-hole TO-92 (Case 29, Style 17) package with standardized lead spacing and mechanical dimensions compliant with ANSI Y14.5M. The package provides adequate thermal conduction for low-power analog use and is compatible with standard PCB mounting and wave soldering processes.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP small-signal amplifier applications.

Compared with BC212BL and BC557B, the BC212B offers the best balance of bandwidth, noise, and gain consistency for general-purpose PNP amplification - making it the preferred choice unless tighter h_FE binning or legacy compatibility dictates an alternative.

Availability

BC212B is available at Aetrix Electronics and suitable for audio preamplifiers, discrete switching circuits, RF buffer stages, and temperature-stable bias networks requiring stable component supply and long-lifecycle availability.

Supply support for BC212B 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

ON Semiconductor (now part of onsemi) is a global semiconductor supplier specializing in energy-efficient power management, analog, and sensing technologies for automotive, industrial, and consumer markets.

The BC212B belongs to ON Semiconductor's legacy bipolar transistor family designed for reliable, low-cost discrete amplification and switching in cost-sensitive, high-volume analog systems.

FAQ

What is the maximum collector-emitter voltage rating for BC212B?

The BC212B has a maximum collector-emitter voltage rating (V_CEO) of −50 Vdc. This rating defines the highest reverse-biased voltage that can be safely applied between collector and emitter while keeping the base open. Exceeding this value risks avalanche breakdown and permanent device damage. The BC212B must be operated within this limit in all circuit configurations, including transient conditions.

Does BC212B support Pb-free assembly processes?

Yes, the BC212BRL1G variant of BC212B is explicitly designated as Pb-free and complies with RoHS Directive 2011/65/EU. It uses lead-free terminations and meets JEDEC J-STD-609A Class 1 moisture sensitivity standards. Standard BC212B (non-G suffix) may contain leaded finishes; always verify the full orderable part number - BC212BRL1G is the recommended Pb-free version of BC212B.

What is the typical noise figure of BC212B and under what conditions is it measured?

The BC212B has a maximum noise figure (NF) of 10 dB, measured at I_C = −0.2 mAdc, V_CE = −5.0 Vdc, R_S = 2.0 kΩ, f = 1.0 kHz, and bandwidth = 200 Hz. This low noise performance makes BC212B suitable for sensitive analog front ends such as electret microphone preamplifiers and sensor signal conditioning circuits where preserving signal-to-noise ratio is essential.

Can BC212B be used in RF applications, and what is its frequency limit?

Yes, BC212B is suitable for RF applications up to approximately 100 MHz due to its 280 MHz current-gain bandwidth product (f_T). It is commonly used in VHF oscillator buffers, IF amplifiers, and broadband signal conditioning stages. Performance beyond 100 MHz depends on external matching, layout parasitics, and bias stability - but the BC212B's f_T confirms usable gain well into the VHF band.

How does the DC current gain (h_FE) of BC212B vary with collector current?

The BC212B exhibits a non-linear h_FE curve: minimum 40 at I_C = −10 mA, typical 60 at I_C = −2 mA, and up to 120 at I_C = −100 mA (all at V_CE = −5 V). Figure 1 in the datasheet shows normalized h_FE peaking near −10 mA and declining at extremes. Designers should select operating points within the 40–120 range and verify gain stability across temperature and production lot variation for BC212B.