onsemi BC636

Overview

BC636 from onsemi is a PNP epitaxial silicon transistor designed for general-purpose switching and linear amplification, with −45 V V_CEO, −1 A continuous collector current, and 100 MHz f_T; it operates in TO−92−3 (case 135AR) package and serves as the complement to BC635 in push-pull amplifier stages and relay driver circuits.

For engineers reviewing the BC636 datasheet, pinout, applications, or equivalent options, key selection considerations include its verified −45 V breakdown rating, DC current gain range of 25–250 across 5 mA to 500 mA, saturation voltage of −0.5 V at −500 mA/−50 mA drive, RoHS-compliant Pb-free construction, and thermal resistance of 125 °C/W under standard FR-4 PCB conditions.

Technical Context

The BC636 is a discrete bipolar junction transistor (BJT) with fixed PNP polarity and epitaxial base structure, optimized for medium-power analog and digital switching where low saturation voltage and stable h_FE over wide current range are required. Its absolute maximum ratings define safe operation up to −45 V V_CEO, −1 A I_C, and 150 °C junction temperature.

Electrical characterization confirms performance under standardized test conditions: h_FE = 25 min at I_C = −5 mA, 40–250 at I_C = −150 mA, and 25 min at I_C = −500 mA; V_CE(sat) = −0.5 V max at I_C = −500 mA/I_B = −50 mA; f_T = 100 MHz at V_CE = −5 V, I_C = −10 mA.

Key Specifications

Pinout & Package

BC636 is housed in TO−92−3 plastic package (case 135AR), with leads formed per standard leadform (4.83 mm × 4.76 mm), and marked "BC636" on top surface. Pin identification follows emitter-collector-base sequence when viewing flat side with leads down and tab up.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC636, BC638 offers extended voltage headroom without layout change, while BC557 trades current capacity for compactness and cost-neither is pin-compatible, and both require circuit revalidation for gain, saturation, and thermal behavior.

Availability

BC636 is available at Aetrix Electronics and suitable for relay driver circuits, DC motor control stages, audio pre-amplifier stages, and power supply enable switches requiring stable component supply and long-term industrial availability.

Supply support for BC636 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BC636 belongs to onsemi's general-purpose bipolar transistor product line, engineered for cost-sensitive, medium-power analog and switching applications demanding reliability, consistent parametric spread, and legacy design compatibility.

FAQ

What is the maximum collector-emitter voltage rating for BC636?

The BC636 has a guaranteed minimum collector-emitter breakdown voltage (V_CEO) of −45 V at I_C = −10 mA and I_B = 0. This rating applies under open-base conditions and defines the upper limit for safe DC or peak AC voltage across collector and emitter terminals in BC636-based designs.

Is BC636 RoHS compliant and lead-free?

Yes, BC636 is explicitly certified as Pb-free, halogen-free/BFR-free, and RoHS compliant per EU Directive 2011/65/EU, as confirmed in the official onsemi datasheet revision 4 (May 2024). The TO−92−3 package carries the "BC636" top mark and meets all applicable environmental compliance requirements for commercial and industrial use.

What is the DC current gain (h_FE) range of BC636 across operating conditions?

The BC636 exhibits h_FE = 25 (min) at I_C = −5 mA, 40–250 at I_C = −150 mA, and 25 (min) at I_C = −500 mA, all measured at V_CE = −2 V. This multi-point specification allows designers to select appropriate bias points for linear amplification or saturated switching while maintaining predictable current amplification behavior in BC636 circuits.

Can BC636 be used as a direct replacement for BC635?

No - BC636 is a PNP transistor and BC635 is its complementary NPN counterpart; they are not interchangeable. The BC636 datasheet explicitly states it is "complement to BC635", meaning they are intended for paired use (e.g., push-pull stages), not substitution. Swapping them would invert logic polarity and likely cause circuit failure in BC636-based designs.

What is the thermal resistance (R_JA) of BC636 under standard PCB conditions?

The BC636 has a junction-to-ambient thermal resistance (R_JA) of 125 °C/W when mounted on a standard FR-4 PCB measuring 76 mm × 114 mm × 1.57 mm with minimum land pattern. This value assumes natural convection and is used to calculate maximum allowable power dissipation versus ambient temperature in BC636 thermal management analysis.