onsemi BD677

Overview

BD677 from onsemi is a plastic medium-power silicon NPN Darlington transistor rated for 60 V_CEO, 4.0 A collector current, and 40 W total device dissipation at T_C = 25°C, with DC current gain ≥750 (IC = 1.5 A, V_CE = 3.0 V), used as output devices in complementary general-purpose amplifier applications.

For engineers reviewing the BD677 datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-225 package thermal resistance (R_θJC = 3.13°C/W), V_CE(sat) ≤ 2.5 V at I_C = 1.5 A / I_B = 30 mA, and equivalence to MJE801 in high-gain switching and linear amplification roles.

Technical Context

The BD677 integrates two monolithic NPN transistors in Darlington configuration to achieve high h_FE (≥750) while maintaining V_BE(on) ≈ 2.5 V and V_CE(sat) ≤ 2.5 V under specified drive conditions. Its safe operating area is bounded by secondary breakdown and thermal limits, with derating to zero power at T_C = 150°C.

Rated for V_CEO = 60 V and V_CBO = 60 V, it supports operation across –55°C to +150°C junction temperature range and complies with RoHS via Pb-free packaging (G suffix). It is complementary to BD676A, BD678A, and BD680A in push-pull amplifier designs.

Key Specifications

Pinout & Package

BD677 is housed in a TO-225 package (Case 77-09, Style 1), with pins arranged as Emitter (Pin 1), Collector (Pins 2 & 4), and Base (Pin 3). The backside tab is electrically connected to the collector.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MJE801 and BD677AG, the BD677 offers identical core switching and amplification capability but is optimized for cost-sensitive legacy designs where 1.5 A h_FE validation suffices and long-term availability is prioritized over marginal gain uplift.

Availability

BD677 is available at Aetrix Electronics and suitable for audio power amplifiers, DC motor drivers, and relay/solenoid interface circuits requiring stable component supply and long-lifecycle support.

Supply support for BD677 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, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The BD677 belongs to onsemi's plastic medium-power Darlington transistor family, designed specifically for cost-effective, high-gain output stages in general-purpose amplifiers and industrial switching applications.

FAQ

What is the maximum continuous collector current rating for BD677?

The BD677 has a maximum continuous collector current (I_C) rating of 4.0 A at case temperature T_C = 25°C. This rating decreases with rising case temperature per the derating curve in the datasheet, reaching zero at T_C = 150°C. For reliable operation at elevated temperatures, heatsinking must be applied to maintain T_C within limits. The BD677 must not be operated beyond this rating without verifying safe operating area boundaries.

Is BD677 pin-compatible with MJE801?

Yes, BD677 is pin-compatible with MJE801: both use TO-225 (Case 77-09, Style 1) packaging with identical pin assignments-Emitter (Pin 1), Collector (Pins 2 & 4), and Base (Pin 3). Electrical specifications including V_CEO, I_C, h_FE, and thermal resistance match precisely. The BD677 and MJE801 may be interchanged without PCB modification in existing designs.

What is the typical V_CE(sat) of BD677 under standard test conditions?

The BD677 exhibits V_CE(sat) ≤ 2.5 V when tested at I_C = 1.5 A and I_B = 30 mA, with V_CE = 3.0 V. This saturation voltage directly impacts conduction losses and thermal rise during switching or linear operation. Designers should verify actual V_CE(sat) under their specific drive conditions, as it increases with temperature and decreases with higher base drive. The BD677's low V_CE(sat) supports efficient power delivery in motor and relay driver applications.

Does BD677 meet RoHS requirements?

Yes, the BD677G variant is Pb-free and RoHS compliant, as confirmed in the official onsemi datasheet (Rev. 16, November 2024). The "G" suffix denotes the Pb-free package. RoHS compliance applies to all homogeneous materials in the device, including die, bond wires, mold compound, and leadframe. BD677 meets EU Directive 2011/65/EU and related regional environmental regulations without exemptions.

What is the safe operating area (SOA) limitation for BD677 at 25°C case temperature?

At T_C = 25°C, the BD677's safe operating area is limited by bonding wire current capacity and secondary breakdown, with maximum allowable I_C decreasing as V_CE increases. For example, it supports 4.0 A up to ~10 V, 2.0 A up to ~30 V, and 1.0 A up to ~60 V. Operation outside the published SOA curve risks immediate failure or accelerated degradation. Designers must reference Figure 2 in the BD677 datasheet and apply appropriate derating for ambient and thermal conditions.