onsemi BD435G

Overview

BD435G from ON Semiconductor is a medium-power NPN epitaxial silicon transistor in TO-126 package, rated for 32 V V_CEO, 4 A DC collector current, and 36 W power dissipation at T_C = 25°C. It serves as a linear amplifier or switching device in industrial power supplies, motor drivers, and relay drivers where robust thermal performance and reliable saturation behavior are required.

For engineers reviewing the BD435G datasheet, pinout, applications, or equivalent options, key selection criteria include its 32 V breakdown rating, 0.2–0.5 V V_CE(sat) at I_C = 2 A / I_B = 0.2 A, h_FE range of 40–130, f_T = 3 MHz, and TO-126 thermal interface compatibility with heatsink mounting.

Technical Context

The BD435G operates as a single NPN bipolar junction transistor optimized for medium-power linear and switching applications. Its epitaxial base structure supports stable h_FE across I_C = 10 mA to 2 A, with V_CE(sat) specified under forced beta (I_C/I_B = 10) to ensure predictable on-state loss in saturated switch designs.

It features a maximum junction temperature of 150°C and safe operating area (SOA) defined up to 10 ms pulse width, enabling use in repetitive transient load conditions. The device is complementary to BD436 and shares identical TO-126 mechanical footprint and terminal assignment.

Key Specifications

Pinout & Package

BD435G is housed in a TO-126 plastic package with integral metal tab for heatsink attachment. The case is electrically connected to the collector terminal, requiring insulated mounting hardware when collector is not at ground potential.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BD435G, BD437G offers direct voltage headroom extension without layout change, while MJD44H11G provides significantly higher ratings at the cost of package and pinout incompatibility-making BD435G optimal for cost-sensitive 24–30 V industrial controls where thermal and electrical margins are sufficient.

Availability

BD435G is available at Aetrix Electronics and suitable for industrial motor drives, programmable logic controller (PLC) output stages, and DC-DC linear regulators requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for BD435G 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 manufacturer specializing in power management, analog, sensor, and discrete solutions for automotive, industrial, cloud, and IoT applications.

BD435G belongs to ON Semiconductor's legacy Fairchild discrete transistor portfolio, designed specifically for medium-power linear amplification and robust switching in industrial control and power conversion equipment.

FAQ

What is the maximum collector-emitter voltage rating for BD435G?

The BD435G has a maximum collector-emitter voltage (V_CEO) rating of 32 V at T_A = 25°C. This rating applies under DC conditions with base open and defines the absolute upper limit for voltage across the collector and emitter terminals. Exceeding this value risks avalanche breakdown and permanent device failure. Designers must ensure operating V_CE remains within this limit, including transients and ripple components, especially in inductive load switching.

Does BD435G have a built-in base-emitter resistor or protection diode?

No, BD435G is a standard three-terminal NPN bipolar junction transistor with no integrated base-emitter resistor or protection diode. It requires external base current limiting and, when used with inductive loads, an external flyback diode across the load to suppress voltage spikes. The absence of internal protection simplifies bias network design but places full responsibility for drive and protection on the circuit designer.

Can BD435G be used in parallel for higher current handling?

BD435G is not recommended for direct paralleling without individual emitter resistors due to positive temperature coefficient of V_BE and process variation in h_FE. Uneven current sharing can occur, leading to thermal runaway in one device. If higher current is needed, consider using a single higher-rated device like BD437G or MJD44H11G instead of paralleling BD435G units.

What is the thermal resistance from junction to case (R_θJC) for BD435G?

The BD435G datasheet does not specify R_θJC explicitly, but its TO-126 package and 36 W P_C rating at T_C = 25°C imply an approximate R_θJC of 0.7°C/W. This value is derived from ΔT = P × R_θJC, where 150°C − 25°C = 125°C rise at 36 W yields ~0.35°C/W - however, industry-standard TO-126 devices typically exhibit 0.6–0.9°C/W. For accurate thermal design, users should refer to ON Semiconductor's official thermal characterization data or perform empirical testing.

Is BD435G RoHS compliant and halogen-free?

Yes, BD435G is RoHS compliant and halogen-free per ON Semiconductor's product compliance documentation. It meets EU Directive 2011/65/EU and IEC 61249-2-21:2011 standards. The "G" suffix in BD435G denotes green (lead-free, halogen-free) packaging, consistent with ON Semiconductor's environmental policy for legacy Fairchild discrete products manufactured post-integration.