onsemi BC640TAR

Overview

BC640TAR from ON Semiconductor (formerly Fairchild) is a PNP epitaxial silicon transistor designed for linear amplification and switching in low-to-medium power circuits, with confirmed V_CEO = −80 V, I_C = −1 A, h_FE = 25–160 (at I_C = −5 mA to −500 mA), and P_C = 1 W. It operates reliably in audio preamplifier stages, relay drivers, and discrete logic-level inverters.

For engineers reviewing the BC640TAR datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-92 package compatibility, guaranteed DC current gain range across collector current, saturation voltage at rated drive, complementary pairing with BC639, and thermal derating above 25°C ambient.

Technical Context

This PNP bipolar junction transistor uses epitaxial base construction to achieve stable h_FE over temperature and consistent V_CE(sat) down to −0.5 V at I_C = −500 mA / I_B = −50 mA. Its breakdown ratings-V_CER = −100 V and V_CEO = −80 V-support operation in inductive load switching with flyback margin.

The device exhibits f_T = 100 MHz under V_CE = −5 V, I_C = −10 mA conditions, enabling use in narrowband RF amplifier front-ends up to ~30 MHz and broadband audio signal paths where phase linearity and gain stability are required.

Key Specifications

Pinout & Package

BC640TAR is housed in a standard TO-92 plastic package with 3 leads, lead-free and RoHS-compliant per manufacturer documentation. Pin assignment follows JEDEC TO-92 outline: Emitter (lead 1), Collector (lead 2), Base (lead 3).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC640TA and MPSA92, BC640TAR offers optimal balance of gain linearity, saturation performance, and cost for general-purpose PNP switching and amplification below 80 V, while maintaining full compatibility with BC639-based complementary circuits.

Availability

BC640TAR is available at Aetrix Electronics and suitable for audio preamplifiers, relay drivers, and discrete logic inverters requiring stable component supply, consistent h_FE binning, and TO-92 mechanical compatibility.

Supply support for BC640TAR 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

ON Semiconductor is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, communications, and computing markets.

The BC640TAR belongs to ON Semiconductor's legacy general-purpose bipolar transistor product line, engineered for reliability in discrete analog and switching functions across consumer, industrial, and infrastructure applications.

FAQ

What is the maximum continuous collector current rating for BC640TAR?

The BC640TAR has a maximum continuous collector current (I_C) rating of −1 A at T_A = 25°C. This rating decreases linearly with rising ambient temperature, reaching approximately −500 mA at 100°C ambient. Derating curves are provided in the official BC640 Rev. C3 datasheet, and operation beyond these limits risks thermal runaway or permanent junction damage. Always verify actual board-level thermal performance when using BC640TAR in high-power applications.

Is BC640TAR pin-compatible with BC639?

No, BC640TAR is not pin-compatible with BC639 - it is electrically complementary but physically inverted: BC639 is an NPN transistor with Emitter-Collector-Base pinout (1-2-3), while BC640TAR is a PNP with Emitter-Collector-Base pinout (1-2-3) in the same TO-92 package. Their pin assignments match, enabling direct PCB layout reuse in complementary circuits such as push-pull amplifiers or H-bridge drivers. BC640TAR must be oriented correctly on the board to maintain polarity.

What is the typical DC current gain (h_FE) of BC640TAR at I_C = −150 mA?

At V_CE = −2 V and I_C = −150 mA, the BC640TAR exhibits a typical DC current gain (h_FE2) of 40, with a guaranteed minimum of 25 and maximum of 160 across production lots. This wide h_FE range reflects process variation and necessitates emitter degeneration or feedback in precision amplifier designs. For BC640TAR, h_FE remains stable across temperature when operated within its specified V_CE and I_C ranges.

Does BC640TAR meet RoHS requirements?

Yes, BC640TAR complies with RoHS Directive 2011/65/EU and is lead-free. The TO-92 package uses matte tin-plated leads and halogen-free molding compound, consistent with ON Semiconductor's environmental compliance program. Full material declarations and test reports are available upon request through Aetrix Electronics' technical support for BC640TAR.

Can BC640TAR be used in RF amplifier applications?

BC640TAR achieves f_T = 100 MHz under V_CE = −5 V, I_C = −10 mA, making it suitable for narrowband RF amplification up to ~30 MHz with adequate gain margin. Its low output capacitance (C_ob < 10 pF) and epitaxial base support stable small-signal performance, but it is not characterized for broadband RF linearity or noise figure. For BC640TAR, RF use is limited to low-power, non-critical receive-stage amplifiers-not transmitter final stages or high-fidelity applications.