onsemi BCW68G

Overview

BCW68G from ON Semiconductor is a PNP general-purpose bipolar junction transistor (BJT) designed for amplifier and switching applications up to 500 mA. It features a maximum collector-emitter voltage of −45 V, DC current gain (h_FE) ranging from 120 to 400 at IC = −10 mA, and a total power dissipation of 350 mW in the SOT-23 package. It is commonly used in low-power audio preamplifiers and discrete logic-level switching circuits.

For engineers reviewing the BCW68G datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, −45 V V_CEO, SOT-23 footprint compatibility, thermal resistance of 357 °C/W, and verified noise figure of 10 dB at 1 kHz - all critical for discrete analog signal conditioning and low-voltage switching designs.

Technical Context

The BCW68G operates as a silicon PNP BJT with a maximum junction temperature of 150 °C and is characterized by its common-emitter configuration. Its f_T of 100 MHz supports moderate-frequency amplification, while Cob = 18 pF and Cib = 105 pF define its small-signal capacitance behavior at 1 MHz under specified bias conditions.

It exhibits defined saturation performance: V_CE(sat) = −1.5 V at I_C = −300 mA / I_B = −30 mA, and V_BE(sat) = −2.0 V at I_C = −500 mA / I_B = −50 mA - confirming suitability for saturated-switching operation in compact DC-DC or load-control stages.

Key Specifications

Pinout & Package

SOT-23 (TO-236AB) 3-lead surface-mount package with gull-wing leads; marked "DG" on top; JEDEC-compliant land pattern recommended per MA03D drawing.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose amplifier applications.

Compared with BCW66G and MMBT4403, BCW68G offers the highest minimum h_FE (120) and lowest noise figure (10 dB), making it preferred for precision analog amplification and applications requiring guaranteed gain at light bias currents.

Availability

BCW68G is available at Aetrix Electronics and suitable for audio preamplifiers, discrete logic-level switching, and complementary pair amplifier circuits requiring stable component supply and SOT-23 footprint consistency.

Supply support for BCW68G 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 (formerly Fairchild Semiconductor) is a global supplier of energy-efficient semiconductor components, specializing in power management, analog, and discrete devices.

The BCW68G belongs to ON Semiconductor's legacy general-purpose BJT product line, engineered for cost-sensitive, high-reliability discrete amplification and switching in consumer, industrial, and communications equipment.

FAQ

What is the maximum collector current rating for BCW68G?

The BCW68G has an absolute maximum continuous collector current (I_C) rating of −800 mA, though its functional description specifies reliable operation up to −500 mA. Derating is required above 25 °C ambient, with thermal resistance R_θJA = 357 °C/W. At elevated temperatures or in high-duty-cycle switching, actual usable current must be reduced to maintain junction temperature ≤ 150 °C. The BCW68G datasheet confirms this limit under Absolute Maximum Ratings.

Is BCW68G suitable for audio amplifier applications?

Yes, BCW68G is explicitly designed for general-purpose amplifier applications, including low-noise audio preamplification. Its 10 dB noise figure at 1 kHz, stable h_FE across bias points, and low C_ob (18 pF) make it appropriate for microphone and sensor signal conditioning. The BCW68G datasheet cites "general-purpose amplifier" in its primary description and provides noise figure, gain, and capacitance data validated for such use - confirming suitability when operated within its −45 V V_CEO and 350 mW power limits.

What package type does BCW68G use, and is it RoHS compliant?

The BCW68G uses the SOT-23 (TO-236AB) 3-lead surface-mount package, marked "DG" on the top surface. Per ON Semiconductor's product change notices and packaging documentation, BCW68G is manufactured in a lead-free, RoHS-compliant process. The device complies with JEDEC standards for SOT-23 dimensions and thermal performance, and its tape-and-reel packing method aligns with automated assembly requirements. This applies specifically to the BCW68G ordering variant documented in Rev. 1.1.0.

How does BCW68G compare to BCW66G in terms of DC current gain?

The BCW68G specifies a minimum h_FE of 120 at I_C = −10 mA, whereas BCW66G specifies a minimum of 100 under identical conditions. Both share the same −45 V V_CEO, −60 V V_CBO, and SOT-23 package, but BCW68G delivers higher guaranteed gain - beneficial for applications requiring robust base-current efficiency or tighter gain tolerance. This difference is confirmed in the Electrical Characteristics tables of their respective datasheets, and both are part of the same Fairchild/ON Semiconductor BJT family.

Can BCW68G be used in switching power supply feedback circuits?

Yes, BCW68G is suitable for discrete error amplifier stages in linear regulators and switching power supplies. Its low output capacitance (C_ob = 18 pF), stable h_FE over temperature, and −45 V V_CEO support reliable closed-loop compensation. The BCW68G datasheet includes common-emitter characteristics and thermal derating curves relevant to continuous bias operation in feedback paths. When used in such roles, ensure V_CE remains within ratings and power dissipation stays below 350 mW with appropriate PCB copper area.