NXP Semiconductors BC640,126

Overview

BC640,126 from Nexperia (formerly Philips Semiconductors) is a PNP medium-power bipolar junction transistor in TO-92 (SOT54) package, rated for −80 V V_CEO, −100 V V_CBO, and −1 A continuous collector current. It delivers DC current gain (h_FE) of 63–250 at I_C = −150 mA and exhibits V_CEsat ≤ −0.5 V at I_C = −500 mA / I_B = −50 mA, making it suitable for audio amplifier output stages and switching regulators.

For engineers reviewing the BC640,126 datasheet, BC640,126 pinout, BC640,126 application, or BC640,126 equivalent, key selection criteria include its PNP polarity, −80 V V_CEO rating, TO-92 thermal resistance (R_th(j-a) = 150 K/W), h_FE consistency across I_C = −5 to −500 mA, and complementary pairing with BC639 for push-pull designs.

Technical Context

The BC640,126 operates as a silicon PNP BJT optimized for linear amplification and medium-current switching. Its structure supports stable h_FE over I_C = −5 mA to −500 mA at V_CE = −2 V, with f_T = 100 MHz enabling audio-frequency signal handling without phase degradation.

Thermal performance is defined for mounting on FR4 PCBs (R_th(j-a) = 150 K/W), and absolute maximum ratings include T_j = 150 °C and T_stg = −65 to +150 °C - confirming suitability for industrial ambient environments without forced cooling.

Key Specifications

Pinout & Package

BC640,126 is housed in a plastic single-ended leaded (through-hole) TO-92 package (SOT54, SC-43A), with 3 leads and standard 2.54 mm lead pitch. The package is compatible with wave soldering and manual prototyping.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC640,115, the BC640,126 offers identical electrical behavior but smaller reel quantity; versus MJD127G, BC640,126 trades lower power handling and higher thermal resistance for compact through-hole integration and cost-sensitive prototyping.

Availability

BC640,126 is available at Aetrix Electronics and suitable for audio amplifiers, relay drivers, DC-DC converters, and linear voltage regulators requiring stable component supply and long-term obsolescence management.

Supply support for BC640,126 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

Nexperia is a global semiconductor expert delivering high-performance, reliable discrete, logic, and MOSFET solutions with focus on efficiency and miniaturization.

The BC640,126 belongs to Nexperia's legacy bipolar transistor portfolio, engineered for cost-effective, robust PNP switching and amplification in consumer, industrial, and automotive auxiliary systems.

FAQ

What is the maximum collector-emitter voltage rating for BC640,126?

The BC640,126 has a maximum collector-emitter voltage (V_CEO) rating of −80 V under open-base conditions. This rating defines the highest voltage the transistor can block in common-emitter configuration without breakdown. Exceeding this value risks permanent damage. The BC640,126 datasheet specifies this limit per IEC 60134 Absolute Maximum Ratings, and it is validated at T_amb ≤ 25 °C on FR4 PCB.

Is BC640,126 pin-compatible with BC639?

No - BC640,126 is a PNP transistor while BC639 is its NPN complement; they share identical TO-92 (SOT54) package and pinout (Base–Collector–Emitter = Pin 1–2–3), but polarity reversal means direct substitution would invert circuit function. The BC640,126 and BC639 are designed for complementary use in push-pull stages, not interchangeability. Always verify biasing and signal polarity before replacement.

What is the typical DC current gain (h_FE) of BC640,126 at 150 mA collector current?

The BC640,126 exhibits a typical DC current gain (h_FE) of 100–250 at V_CE = −2 V and I_C = −150 mA, as specified in the Philips/Nexperia datasheet. This range reflects production variation and ensures predictable base drive sizing. At lower currents (e.g., −5 mA), h_FE starts at 63; at higher currents (−500 mA), it drops to ≥40. The BC640,126 maintains this behavior across ambient temperatures up to 125 °C.

Can BC640,126 be used in surface-mount designs?

No - BC640,126 is a through-hole device in TO-92 (SOT54) package with 3 axial leads intended for insertion and wave soldering. It lacks surface-mount terminations or land patterns. For SMT equivalents, consider Nexperia's PBSS4041T (SOT23, PNP, −40 V, −1 A) or MMBT640 (SOT23, −80 V, −0.5 A), but note differences in gain, saturation voltage, and thermal performance versus BC640,126.

What is the thermal resistance from junction to ambient for BC640,126?

The BC640,126 has a thermal resistance from junction to ambient (R_th(j-a)) of 150 K/W when mounted on a standard FR4 printed-circuit board, per datasheet test condition. This value assumes no added heatsink and defines the temperature rise per watt dissipated. At its 0.83 W total power dissipation limit, this yields a theoretical ΔT of 124.5 K above ambient - confirming need for derating above 25 °C ambient. The BC640,126 datasheet explicitly ties this value to JEDEC-standard FR4 mounting.