onsemi BD675G

Overview

BD675G 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 45 V collector-emitter breakdown voltage. It delivers 4.0 A continuous collector current, 40 W total device dissipation at 25°C, and operates across –55°C to +150°C junction temperature range.

For engineers reviewing the BD675G datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-225 package thermal resistance (3.13°C/W), V_CE(sat) of ≤2.5 V at I_C = 1.5 A / I_B = 30 mA, and complementary pairing with BD676-series PNP Darlingtons in push-pull configurations.

Technical Context

The BD675G implements a monolithic NPN Darlington pair structure, integrating driver and output transistors on a single die to achieve minimum h_FE of 750 at I_C = 1.5 A and V_CE = 3.0 V. Its safe operating area is thermally limited at low V_CE and secondary-breakdown constrained at high V_CE, with bonding wire current limit defining the upper IC boundary.

Rated for 45 V V_CEO and 5.0 V V_EBO, the device supports emitter-base reverse bias up to 5 Vdc and exhibits I_CEO ≤ 500 µA at half-rated V_CEO. Its TO-225 case provides direct heatsink mounting via the metal tab (pin 4), with collector terminals electrically tied to the case.

Key Specifications

Pinout & Package

BD675G is housed in a TO-225 package (Case 77-09, Style 1) with collector connected to the metal tab (pins 2 and 4), emitter at pin 1, and base at pin 3. The package supports direct heatsink mounting and provides mechanical robustness for medium-power applications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BD675G, MJE800 offers higher voltage and power ratings but requires validation of thermal interface due to different R_JC (2.5°C/W), while BD677G provides seamless voltage scalability within the same family-both enable design reuse but differ in voltage headroom and thermal management trade-offs.

Availability

BD675G is available at Aetrix Electronics and suitable for audio power amplifiers, DC motor drivers, relay/solenoid interfaces, and linear regulator pass elements requiring stable component supply and legacy-compatible medium-power Darlington performance.

Supply support for BD675G 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 specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BD675G belongs to onsemi's legacy medium-power discrete transistor portfolio, engineered for cost-sensitive, thermally demanding linear and switching applications where high current gain and rugged packaging are essential.

FAQ

What is the maximum collector-emitter voltage rating for BD675G?

The BD675G has a maximum collector-emitter voltage (V_CEO) rating of 45 Vdc under open-base conditions with I_C = 50 mA. This rating defines the absolute upper limit for voltage applied between collector and emitter before avalanche breakdown occurs. Exceeding this value risks permanent device damage, and designers must maintain adequate safety margin-especially in inductive load switching where voltage spikes may occur. The BD675G datasheet confirms this value in both Maximum Ratings and Electrical Characteristics tables.

Is BD675G pin-compatible with BD677G or BD679G?

Yes, BD675G is pin-compatible with BD677G and BD679G-they all use the TO-225 package (Case 77-09, Style 1) with identical pin 1 (emitter), pins 2/4 (collector), and pin 3 (base) assignments. However, their voltage ratings differ: BD675G is rated for 45 V V_CEO, BD677G for 60 V, and BD679G for 80 V. Substituting BD675G for higher-voltage variants requires verifying that system operating voltage stays within its 45 V limit to avoid failure.

What is the typical base-emitter on voltage for BD675G?

The BD675G exhibits a base-emitter on voltage (V_BE(on)) of approximately 2.5 Vdc when operated at I_C = 1.5 A and V_CE = 3.0 Vdc. This elevated V_BE reflects its Darlington configuration-two series-connected base-emitter junctions-and directly impacts base drive circuit design. Engineers must ensure sufficient base supply voltage and current capability (≥30 mA for saturation) to fully turn on the BD675G without excessive base resistor power loss.

Does BD675G require a heatsink in standard operation?

Yes, BD675G typically requires a heatsink when dissipating more than ~5–8 W continuously, due to its 3.13°C/W junction-to-case thermal resistance and 150°C maximum junction temperature. At full 40 W dissipation, even with ideal heatsinking, case temperature would approach 125°C-exceeding most ambient limits. Practical designs using BD675G at >1 A average current should include a finned aluminum heatsink with thermal interface material and verify junction temperature using the formula T_J = T_C + (P_D × R_JC).

Is BD675G suitable for PWM motor control applications?

Yes, BD675G is suitable for PWM motor control at frequencies up to ~10 kHz, provided gate/base drive is optimized for fast turn-on/turn-off. Its Darlington structure introduces inherent storage time delay, so base drive must deliver ≥30 mA peak current and include active base turn-off (e.g., pull-down resistor or transistor) to minimize fall time. The BD675G's safe operating area curve (Figure 2) confirms reliable operation at I_C = 2–3 A and V_CE < 20 V-typical for 12–24 V brushed motor drives.