onsemi BD675A

Overview

BD675A from onsemi is a plastic medium-power silicon NPN Darlington transistor designed for general-purpose amplifier output stages and switching applications requiring high DC current gain and 4.0 A continuous collector current. It features 45 V collector-emitter breakdown voltage (V_CEO), 40 W total device dissipation at T_C = 25°C, and operates across –55°C to +150°C junction temperature range. It is commonly used in relay drivers, power supplies, and motor control circuits.

For engineers reviewing the BD675A datasheet, pinout, applications, or equivalent options, key selection criteria include its V_CEO = 45 V rating, h_FE ≥ 750 at I_C = 2.0 A, V_CE(sat) ≤ 2.8 V under specified drive conditions, thermal resistance R_θJC = 3.13°C/W, and TO-225 package compatibility with heatsink mounting.

Technical Context

The BD675A integrates two NPN transistors in monolithic Darlington configuration to achieve high current gain while maintaining single-package simplicity. Its base-emitter turn-on voltage is 2.5 V, and it supports safe operation up to 4.0 A collector current with appropriate heatsinking.

It is complementary to PNP devices BD676/BD676A and shares electrical and mechanical equivalence with MJE800 series only for BD677/BD677A and higher-voltage variants - not applicable to BD675A. The device is Pb-free and RoHS compliant, packaged in TO-225 (Case 77-09) with emitter-base-collector pinout.

Key Specifications

Pinout & Package

BD675A is housed in a TO-225 plastic package (Case 77-09, Style 1), featuring three leads with internal tab connected to collector. The case is electrically isolated from the collector via molded plastic but thermally coupled for heatsink mounting.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJE800 and BD675G, the BD675A provides optimized gain guarantee at 2.0 A drive - critical for robust saturation in high-current switching - while retaining the exact TO-225 pinout and thermal profile needed for drop-in replacement in legacy BD675-series designs.

Availability

BD675A is available at Aetrix Electronics and suitable for relay drivers, DC motor controllers, and linear power supply designs requiring stable component supply, long-lifecycle support, and RoHS-compliant manufacturing.

Supply support for BD675A 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 focused on energy-efficient electronics, delivering high-performance analog, discrete, and power management solutions.

The BD675A belongs to onsemi's legacy medium-power Darlington transistor family, engineered for ruggedized industrial switching and amplification where high current gain and thermal reliability are prioritized over ultra-high-speed response.

FAQ

What is the maximum collector-emitter voltage rating for BD675A?

The BD675A has a maximum collector-emitter voltage (V_CEO) rating of 45 Vdc, verified per onsemi's BD675/D datasheet under test condition I_C = 50 mA and I_B = 0. This rating defines the absolute upper limit for safe DC or peak pulse operation; exceeding it risks avalanche breakdown and permanent damage to the BD675A.

Is BD675A pin-compatible with BD675G?

Yes, BD675A is pin-compatible with BD675G - both use identical TO-225 (Case 77-09, Style 1) packaging with emitter-base-collector pinout (Pin 1 = E, Pins 2/4 = C, Pin 3 = B). However, BD675A guarantees h_FE ≥ 750 at I_C = 2.0 A, whereas BD675G specifies the same gain at I_C = 1.5 A, making BD675A more suitable for full-rated current applications.

Does BD675A require a heatsink in typical applications?

Yes, BD675A requires a heatsink in any application where power dissipation exceeds ~1.5 W continuously. With R_θJC = 3.13°C/W and max T_J = 150°C, even at 25°C ambient, sustained operation above 1.5 A at V_CE(sat) ≈ 2.5 V generates >3.75 W - necessitating a heatsink to keep junction temperature within specification. The BD675A's collector-tab design facilitates direct mounting.

What is the base-emitter turn-on voltage for BD675A?

The BD675A exhibits a base-emitter on voltage (V_BE(on)) of 2.5 Vdc when operated at I_C = 2.0 A and V_CE = 3.0 V, as specified in the onsemi BD675/D datasheet. This elevated V_BE reflects the dual-V_BE drop inherent to Darlington topology and must be accounted for in driver circuit design to ensure sufficient base current.

Is BD675A suitable for PWM motor control?

Yes, BD675A is suitable for PWM motor control at frequencies up to ~5 kHz, provided gate/base drive is sufficiently robust (≥40 mA peak) and dead-time management prevents shoot-through. Its Darlington structure introduces slower turn-off than MOSFETs, but its 4.0 A rating and thermal robustness make it viable for low-frequency, high-torque brushed DC motor drives where cost and simplicity are priorities over switching speed.