onsemi BC635_J35Z

Overview

BC635_J35Z from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for switching and amplifier applications, with V_CEO = 45 V, I_C = 1 A, P_C = 1 W, h_FE = 25–250 (at I_C = 5–500 mA), and TO-92 package - used in low-voltage DC power control circuits such as relay drivers and signal amplification stages.

For engineers reviewing the BC635_J35Z datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO/I_C ratings, h_FE grouping at multiple bias points, saturation voltage under 500 mA drive, thermal limits up to 150°C junction temperature, and TO-92 mechanical compatibility with legacy through-hole PCB layouts.

Technical Context

This discrete NPN bipolar junction transistor operates in active, saturation, and cutoff regions with defined breakdown voltages (V_CEO = 45 V, V_CER = 45 V, V_CES = 45 V) and guaranteed DC current gain across three test conditions: h_FE1 ≥25 at I_C = 5 mA, h_FE2 ≥40 at I_C = 150 mA, and h_FE3 ≥40 at I_C = 500 mA.

It exhibits V_CE(sat) ≤ 0.5 V at I_C = 500 mA / I_B = 50 mA and V_BE(on) ≈ 1 V under same conditions, with f_T = 100 MHz at V_CE = 5 V / I_C = 10 mA - confirming suitability for medium-speed switching and audio-frequency amplification where gain stability and low saturation loss are required.

Key Specifications

Pinout & Package

BC635_J35Z is housed in a standard TO-92 plastic package with 3 leads: Emitter (Pin 1), Collector (Pin 2), Base (Pin 3). Lead spacing and outline conform to JEDEC TO-92 outline variations for through-hole mounting and manual soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC635_J35Z, BC547B offers higher h_FE but insufficient I_C for relay/motor loads, while PN2222A matches TO-92 footprint and thermal performance but trades 5 V V_CEO margin for broader industry validation in industrial control firmware stacks.

Availability

BC635_J35Z is available at Aetrix Electronics and suitable for relay driver circuits, DC motor speed control, audio pre-amplifier stages, and LED current regulator designs requiring stable component supply with consistent parametric performance across production batches.

Supply support for BC635_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 BC635_J35Z belongs to Fairchild's legacy general-purpose bipolar transistor family, engineered for cost-sensitive, high-reliability through-hole applications in industrial controls, consumer electronics, and power interface circuits.

FAQ

What is the maximum collector-emitter voltage rating for BC635_J35Z?

The BC635_J35Z has a V_CEO rating of 45 V, meaning it can safely withstand up to 45 volts between collector and emitter with the base open. This value is confirmed in the Absolute Maximum Ratings table and repeated in the Electrical Characteristics section under BV_CEO test condition (I_C = 10 mA, I_B = 0). Exceeding this voltage risks avalanche breakdown and permanent damage to the BC635_J35Z.

Does BC635_J35Z have a specified DC current gain range?

Yes, BC635_J35Z specifies three h_FE values: minimum 25 at I_C = 5 mA, minimum 40 at I_C = 150 mA, and minimum 40 at I_C = 500 mA - all tested at V_CE = 2 V. These multi-point guarantees allow designers to size base resistors confidently across linear and saturated operating modes, ensuring predictable behavior in both amplifier and switch applications using the BC635_J35Z.

What is the package type and pin configuration of BC635_J35Z?

The BC635_J35Z uses a TO-92 plastic package with standardized lead arrangement: Pin 1 is Emitter, Pin 2 is Collector, Pin 3 is Base - verified in the "Package Dimensions" section and schematic diagrams of the original Fairchild datasheet. This pinout is consistent across BC635/637/639 variants and aligns with JEDEC TO-92 outline drawings, ensuring mechanical compatibility with existing through-hole footprints for the BC635_J35Z.

Can BC635_J35Z be used in switching applications?

Yes, BC635_J35Z is explicitly rated for switching applications per its product description and electrical specifications. Its V_CE(sat) ≤ 0.5 V at I_C = 500 mA / I_B = 50 mA and f_T = 100 MHz confirm fast turn-on/turn-off capability and low conduction loss. The BC635_J35Z is commonly deployed in relay drivers, PWM motor controllers, and LED dimming circuits where reliable saturation and thermal stability are required.

What is the junction temperature limit for BC635_J35Z?

The BC635_J35Z has a maximum junction temperature (T_J) of 150°C, as stated in the Absolute Maximum Ratings table. This limit defines the highest allowable silicon die temperature during operation. To maintain reliability, designers must ensure thermal resistance from junction-to-ambient (R_θJA) - dependent on PCB copper area and airflow - keeps actual T_J below 150°C under worst-case power dissipation (1 W at 25°C ambient), especially in enclosed enclosures where the BC635_J35Z operates.