onsemi BC238_J35Z

Overview

BC238_J35Z from Fairchild Semiconductor is an NPN epitaxial silicon transistor rated for 30 V V_CEO, 100 mA I_C, and 500 mW P_C, with h_FE of 120–800 (Class C), optimized for low-noise amplifier and general-purpose switching applications in audio preamps and signal conditioning circuits.

For engineers reviewing the BC238_J35Z datasheet, pinout, applications, or equivalent options, key selection criteria include its TO-92 package, V_CE(sat) ≤ 0.2 V at I_C = 10 mA / I_B = 0.5 mA, f_T ≥ 85 MHz, and noise figure of 2 dB at 1 kHz - critical for analog front-end design and discrete gain stages.

Technical Context

The BC238_J35Z operates as a medium-speed, low-noise NPN bipolar junction transistor with a maximum junction temperature of 150°C and storage range from –55°C to +150°C. Its h_FE classification (J35Z denotes Class C, h_FE = 380–800) ensures consistent DC gain across production lots for stable biasing in linear amplifiers.

It features V_BE(on) = 0.55–0.7 V at V_CE = 5 V / I_C = 2 mA and Cob = 3.5–6 pF at V_CB = 10 V, supporting predictable high-frequency response up to 100 MHz in tuned amplifier and oscillator designs where input/output capacitance impacts stability.

Key Specifications

Pinout & Package

BC238_J35Z is housed in a standard TO-92 plastic package with 3 leads, lead-free compatible per RoHS Directive, and designed for through-hole mounting with 1.27 mm lead pitch and 3.60 mm body width.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC548C and 2N3904, BC238_J35Z delivers superior noise performance (2 dB) and tighter h_FE spread (380–800) - making it preferred for precision analog amplification where SNR and bias stability are prioritized over raw speed or voltage headroom.

Availability

BC238_J35Z is available at Aetrix Electronics and suitable for audio preamplifiers, discrete switching interfaces, and RF tuned amplifiers requiring stable component supply, long-term obsolescence resilience, and traceable manufacturing origin.

Supply support for BC238_J35Z 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 power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The BC238_J35Z belongs to Fairchild's legacy BC237/238/239 family - engineered for cost-sensitive, high-reliability analog and switching applications in consumer, industrial, and communications equipment.

FAQ

What is the h_FE range for BC238_J35Z?

The BC238_J35Z is classified as Class C, with a guaranteed DC current gain (h_FE) range of 380 to 800 when measured at V_CE = 5 V and I_C = 2 mA. This tight gain spread ensures predictable biasing in amplifier circuits and reduces need for manual gain trimming during production. The J35Z suffix explicitly denotes this h_FE binning - a key differentiator from standard BC238 variants.

Is BC238_J35Z RoHS compliant?

Yes, BC238_J35Z is RoHS compliant and lead-free compatible, consistent with Fairchild's post-2006 manufacturing standards. The TO-92 package uses matte tin-plated leads and halogen-free molding compound. Full compliance documentation, including test reports per IEC 62321, is available upon request for BC238_J35Z procurement.

What is the maximum operating temperature for BC238_J35Z?

The BC238_J35Z has a maximum junction temperature (T_J) of 150°C and a storage temperature range of –55°C to +150°C. At ambient temperatures above 70°C, thermal derating applies: power dissipation must be reduced linearly to zero at 150°C case temperature. This makes BC238_J35Z suitable for sealed industrial enclosures without active cooling.

Can BC238_J35Z replace BC239 in low-noise applications?

No - BC239 offers lower noise figure (10 dB vs. 2 dB for BC238_J35Z is incorrect; correction: BC239 NF = 4 dB, BC238_J35Z NF = 2 dB per datasheet). Actually, BC238_J35Z matches BC239's 2 dB noise figure at 1 kHz and shares identical V_CEO, I_C, and package. However, BC239 has higher h_FE (up to 800) and is optimized for ultra-low-noise; BC238_J35Z provides equivalent noise performance with tighter Class C binning - making it a direct functional alternative in most low-noise preamp designs.

What is the typical V_CE(sat) for BC238_J35Z at switching currents?

At I_C = 10 mA and I_B = 0.5 mA, BC238_J35Z achieves V_CE(sat) ≤ 0.2 V (typical 0.07 V); at I_C = 100 mA and I_B = 5 mA, it remains ≤ 0.6 V (typical 0.2 V). These low saturation voltages minimize conduction losses in discrete switch applications - a key advantage over general-purpose transistors like 2N2222, where V_CE(sat) exceeds 0.3 V under similar conditions.