onsemi BC237C

Overview

BC237C from onsemi is an NPN silicon general-purpose amplifier transistor in TO-92 package, rated for V_CEO = 45 V, I_C = 100 mA, P_D = 350 mW at T_A = 25°C, with h_FE = 200–500 (at I_C = 2 mA, V_CE = 5 V), used in low-noise audio preamplifier stages and signal switching circuits.

For engineers reviewing the BC237C datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain range, V_CE(sat) ≤ 0.2 V at I_C/I_B = 10, f_T ≥ 150 MHz, C_obo = 4.5 pF, and thermal resistance R_JA = 357 °C/W - all critical for analog gain stability and high-frequency small-signal performance.

Technical Context

The BC237C operates as a linear NPN bipolar junction transistor optimized for low-noise amplification and medium-speed switching. Its h_FE binning (C-grade) guarantees minimum DC current gain of 200 at I_C = 2 mA, V_CE = 5 V, and maximum of 500 under same conditions, with f_T = 150–200 MHz ensuring usable bandwidth up to VHF.

Thermal design is constrained by R_JA = 357 °C/W and R_JC = 125 °C/W, requiring heatsinking only above ~150 mW dissipation. The device exhibits V_BE(on) = 0.62–0.83 V and V_CE(sat) = 0.07–0.2 V, enabling efficient biasing in Class-A amplifier topologies and saturated switch configurations.

Key Specifications

Pinout & Package

BC237C is housed in TO-92 (Case 29, Style 17) plastic package with 3 leads, lead-free option available (BC237CG). Package dimensions conform to ANSI Y14.5M, with standard lead spacing (P = 2.54 mm) and mechanical tolerances per datasheet Issue AL.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC237C, BC547C offers higher and more tightly binned h_FE but identical voltage ratings, while 2N3904 trades gain for bandwidth and lower noise at high frequencies - making BC237C optimal for cost-sensitive, medium-bandwidth analog gain blocks where consistent low-noise performance is prioritized.

Availability

BC237C is available at Aetrix Electronics and suitable for audio preamplifiers, signal switching circuits, RF detector biasing, and oscillator active elements requiring stable component supply across industrial, consumer, and prototyping environments.

Supply support for BC237C 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 IoT applications.

The BC237C belongs to onsemi's legacy general-purpose bipolar transistor family, designed specifically for cost-effective, reliable amplification and switching in low-power analog and mixed-signal systems.

FAQ

What is the guaranteed h_FE range for BC237C at I_C = 2 mA and V_CE = 5 V?

The BC237C is binned to guarantee h_FE between 200 and 500 under those exact test conditions, as specified in the "ON CHARACTERISTICS" table of the BC237/D datasheet Rev. 4. This range ensures predictable DC biasing without manual gain adjustment, and the BC237C maintains this specification across its full operating temperature range of −55°C to +150°C.

Is BC237C pin-compatible with BC237B or BC239C?

Yes - BC237C shares identical TO-92 package, pinout (Collector/Base/Emitter on pins 1/2/3), and mechanical footprint with BC237B and BC239C. However, BC239C has lower V_CEO (25 V vs. 45 V) and different h_FE binning, so direct substitution requires verification of voltage and gain requirements in the target circuit.

Does BC237C support Pb-free soldering processes?

Yes - the BC237CG variant is the official Pb-free version of BC237C, fully compliant with RoHS Directive 2011/65/EU. It uses matte tin lead finish and passes JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1), supporting both reflow and wave soldering without derating.

What is the maximum power dissipation of BC237C at 70°C ambient temperature?

At T_A = 70°C, BC237C's power dissipation must be derated from 350 mW at 25°C using PD = 350 mW − (70 − 25) × 2.8 mW/°C = 224 mW. This value assumes free-air convection; adding 1 cm² copper pour reduces effective R_JA and increases allowable dissipation.

Can BC237C be used in RF oscillator circuits up to 100 MHz?

No - BC237C's f_T is rated 150–200 MHz under specific conditions (I_C = 0.5 mA, V_CE = 3 V), but practical oscillator use is limited to ≤50 MHz due to gain roll-off and phase shift. For 100 MHz operation, devices like 2N3904 (f_T = 300 MHz) or MMBT2222A are better matched, while BC237C remains optimal for sub-50 MHz Colpitts or Hartley oscillators.