onsemi BC238CTA

Overview

BC238CTA from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for low-noise amplifier and general-purpose switching applications, with V_CEO = 25 V, I_C = 100 mA, P_C = 500 mW, h_FE = 380–800 (Class C), and f_T = 85 MHz at V_CE = 5 V, I_C = 10 mA - used in audio preamplifier stages and discrete logic interface circuits.

For engineers reviewing the BC238CTA datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-92 package, Class C h_FE gain binning, low V_CE(sat) of 0.2 V at I_C = 10 mA / I_B = 0.5 mA, and verified noise figure of 4 dB at 1 kHz with R_G = 2 kΩ.

Technical Context

The BC238CTA operates as a medium-speed, low-noise NPN bipolar junction transistor optimized for linear amplification and saturated switching. Its h_FE classification (C: 380–800) ensures consistent current gain across production lots, while its f_T of 85 MHz supports audio-frequency and low-speed digital signal handling.

It features V_CEO = 25 V and V_CES = 30 V ratings, enabling use in 24 V rail systems with margin; V_BE(on) = 0.62 V typical at I_C = 2 mA confirms reliable turn-on with standard TTL/CMOS drive levels, and Cob = 3.5–6 pF minimizes high-frequency loading in RF-coupled stages.

Key Specifications

Pinout & Package

BC238CTA is housed in a through-hole TO-92 plastic package with standardized lead configuration: leads are arranged in linear order (1–2–3) when viewed from the flat side with leads pointing downward.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC239CTA and PN2222A, BC238CTA uniquely balances high h_FE, low noise, and moderate voltage rating - making it optimal for compact, battery-powered audio amplifiers and precision-switching interfaces where both gain stability and signal fidelity matter.

Availability

BC238CTA is available at Aetrix Electronics and suitable for audio preamplifier design, discrete logic level translation, and low-power LED/relay driver applications requiring stable component supply and consistent h_FE binning.

Supply support for BC238CTA 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

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in analog and discrete power components, later acquired by ON Semiconductor in 2016.

The BC238CTA belongs to the BC237/238/239 family - engineered for general-purpose amplification and switching in cost-sensitive, space-constrained consumer and industrial electronics.

FAQ

What is the h_FE range for BC238CTA?

The BC238CTA is classified as Class C, with a guaranteed DC current gain (h_FE) range of 380 to 800 at V_CE = 5 V and I_C = 2 mA. This tight binning ensures predictable biasing in amplifier circuits without gain compensation networks. The BC238CTA's h_FE performance is validated per Fairchild's Rev. A2 datasheet and remains consistent across production lots meeting this specification.

Is BC238CTA suitable for low-noise audio applications?

Yes, BC238CTA delivers a noise figure of 4 dB at 1 kHz with R_G = 2 kΩ, making it appropriate for low-noise audio preamplifier stages. Its performance is specifically characterized and binned for this purpose within the BC237/238/239 series. When used in electret microphone biasing or sensor signal conditioning, BC238CTA maintains signal integrity without requiring external noise-reduction circuitry.

What is the maximum collector-emitter voltage rating for BC238CTA?

The BC238CTA has a V_CEO rating of 25 V and a V_CES rating of 30 V, both specified at T_A = 25°C. These values define its safe operating area in common-emitter configurations with open base. Exceeding 25 V in normal operation risks avalanche breakdown; derating is recommended for elevated temperatures or reliability-critical designs using BC238CTA.

Does BC238CTA have the same pinout as PN2222A?

Yes, BC238CTA uses the standard TO-92 package with pin 1 = Collector, pin 2 = Base, pin 3 = Emitter - identical to PN2222A and most legacy NPN transistors in that outline. This allows direct physical replacement in existing layouts, though electrical differences (e.g., h_FE, NF, V_CE(sat)) must be verified for functional equivalence in the BC238CTA application.

What is the typical V_CE(sat) for BC238CTA under switching conditions?

The BC238CTA exhibits a typical V_CE(sat) of 0.07 V and a maximum of 0.2 V at I_C = 10 mA and I_B = 0.5 mA, confirming strong saturation behavior. At higher currents (I_C = 100 mA, I_B = 5 mA), V_CE(sat) rises to ≤0.6 V. These values enable efficient use of BC238CTA in low-loss switching roles such as LED drivers and logic-level translators.