onsemi BC635_D75Z

Overview

BC635_D75Z from Fairchild Semiconductor is an NPN epitaxial silicon transistor designed for general-purpose switching and linear amplification, with V_CEO = 45 V, I_C = 1 A, P_C = 1 W, h_FE ≥ 25 at I_C = 5 mA, and f_T = 100 MHz - used in low-voltage power supply control and audio preamplifier stages.

For engineers reviewing the BC635_D75Z datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO/I_C derating behavior, TO-92 thermal resistance, h_FE grouping consistency at 5 mA and 500 mA, and saturation voltage under 50 mA base drive.

Technical Context

This device operates as a medium-power bipolar junction transistor with fixed-emitter configuration, optimized for DC-coupled gain stages and resistive-load switching. Its h_FE exhibits dual-tier specification (≥25 at 5 mA, ≥40 at 150 mA), and V_CE(sat) is guaranteed ≤0.5 V at I_C = 500 mA / I_B = 50 mA.

Thermal performance is defined by T_J = 150°C maximum and TO-92 package R_θJA ≈ 200°C/W (free-air), requiring board-level copper area for sustained 1 W dissipation. Cutoff leakage is tightly controlled: I_CBO ≤ 0.1 µA at V_CB = 30 V.

Key Specifications

Pinout & Package

BC635_D75Z is housed in a standard TO-92 plastic package with 3 leads, rated for 150°C junction temperature and -65°C to +150°C storage range. Lead finish is matte tin, lead-free compatible per J-STD-020.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN switching and amplification applications.

Compared with BC635_D75Z, BC635_TL offers identical performance in automated manufacturing contexts, while MPSA18 provides superior high-frequency gain and tighter h_FE tolerance at increased unit cost and reduced supply chain ubiquity.

Availability

BC635_D75Z is available at Aetrix Electronics and suitable for audio preamplifiers, DC motor drivers, and linear voltage regulator designs requiring stable component supply, consistent h_FE binning, and TO-92 mechanical compatibility.

Supply support for BC635_D75Z 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 analog and discrete semiconductor manufacturer, acquired by ON Semiconductor in 2016; known for robust bipolar and MOSFET product lines serving industrial and consumer markets.

The BC635_D75Z belongs to Fairchild's BC63x family of general-purpose NPN transistors, engineered for cost-sensitive, medium-speed switching and analog amplification in non-automotive industrial equipment.

FAQ

What is the maximum continuous collector current rating for BC635_D75Z?

The BC635_D75Z has a maximum continuous collector current (I_C) rating of 1 A at T_A = 25°C. This value decreases with rising ambient temperature due to thermal derating; at 70°C ambient, the usable I_C drops to approximately 0.65 A. The BC635_D75Z must be mounted on adequate copper area to maintain junction temperature below 150°C under sustained load.

Is BC635_D75Z pin-compatible with BC637_D75Z or BC639_D75Z?

No - although BC635_D75Z, BC637_D75Z, and BC639_D75Z share identical TO-92 package and pinout (Emitter-Collector-Base), they differ in absolute maximum ratings: BC635_D75Z has V_CEO = 45 V, while BC637_D75Z is rated for 60 V and BC639_D75Z for 80 V. Substituting BC635_D75Z in a circuit designed for BC639_D75Z risks premature breakdown.

What is the typical DC current gain (h_FE) of BC635_D75Z at 500 mA collector current?

Per the Fairchild datasheet, BC635_D75Z guarantees h_FE ≥ 40 at V_CE = 2 V and I_C = 150 mA, and ≥25 at I_C = 500 mA. Typical h_FE at I_C = 500 mA is ~60–100 depending on unit variation. The BC635_D75Z is not specified for high-current gain consistency beyond 150 mA, so designs relying on h_FE > 40 at 500 mA should verify with sample testing.

Does BC635_D75Z meet RoHS requirements?

Yes - BC635_D75Z manufactured under Fairchild's Rev. B2 (December 2002) and later revisions complies with RoHS Directive 2002/95/EC, featuring lead-free matte tin lead finish and halogen-free molding compound. The BC635_D75Z part number specifically denotes RoHS-compliant packaging and material content per Fairchild's product change notice PCN-02-001.

Can BC635_D75Z be used in avalanche mode?

No - BC635_D75Z is not rated or characterized for controlled avalanche operation. Its V_CEO = 45 V and V_CER = 45 V indicate no intentional energy-rated avalanche capability. Using BC635_D75Z in repetitive avalanche conditions may cause parametric shift or catastrophic failure. For such applications, purpose-designed avalanche-rated transistors like the FMMT417 should be selected instead of BC635_D75Z.